Mitsubishi Repair Problems? Ask a Mechanic for Answers ASAP
Hi!We can go ahead and do the thermostat, however you would really expect it to be a P0128 if it were the thermostat. P0128 indicates the coolant temp sensor is not reaching temperature in time, however the P0125 indicates that when compared to the coolant temp sensor (which is implied reading normally) the O2 sensors have not switched to live readings yet. This is usually going to be an issue with the sensors being a bit lazy (the front sensors specifically).
Lets get those changed out first and foremost... as I mentioned before there is a software update for this problem as well, however being out of the US they aren't going to have that file in their database most likely. If they are open to it we can probably work around it if I can get it exported for them, however there is an element of risk here (if they goof up, you will need a new ecu), so trying just the sensor portion first is more desirable of course.
I did some looking this afternoon to see if I could locate the flash file, but it doesn't look like it is stored locally anymore (to get it the scan tool has to download it, so I need a same model/year/emissions pack present to get the file. So it is probably just as well there.The 450... do we have the new cap yet or not yet? I don't suspect any relation, but we definitely would prefer a fully functioning system before testing that.
Also, does the code come right back (Within on key-on for example) or if cleared does it take a long time to return?
That's the deal with seeing if it comes back... the sensor is constantly monitored, so if for example you had a broken wire to the sensor as we sometimes see, the code would come right back. Not coming right back means possible sensor, or possible unrelated problem manifesting in a P0450 (like an abnormal vacuum/pressure condition in the tank causing it to give a reading that while accurate, is out of range).
The fuel line squirting is normal, that means it is retaining pressure which is good.
Left and right are as you sit in the driver seat. So being a US vehicle left front would be drivers side nearest the engine, right front would be passenger side nearest the engine.The Denso ones you want are the direct replacement Denso brand. They will usually be packaged as First Time Fit or Direct Fit. As long as its a blue box that says Denso and the harness is plug and play (no crimping wires etc) you'll be fine. If the old sensors were cut and splice it shouldn't matter as they are supposed to cut them into the old sensor wiring... not into the engine harness. So you would just unplug them and throw them away and plug the new sensors in.
Ouch yeah thats a huge variable with the thermostat. The stock thermostat is 190F, so yeah that 170 is killing you there. You need to get a stock stat in there as you are drastically over cooling the engine with that thing.
Yeah the spec thermostat is 88C... you want that. Even a 180-185 would potentially cause issues. These systems are super particular about temperature regulation due to the emissions requirements. Its not like the '80s cars :)
I checked the VIN but due to the age the records have been purged for anything after 2003. The only record I have for that VIN is a battery replacement in 9/2003. If I recall correctly the earliest release of the P0125 update was around January 2003, so there is possibility it was done, but I would say odds are slim. If you can get the ECU information printed out from the scan tool I can tell what software version it is on... I would not suspect that it was done though since this issue was so infrequent to occur and the repair history goes so close to when it was released, it would be fairly improbable odds it developed the issue and got the repair done inside of those few months we are missing.
They can read it on their MUT. They just need to choose <--05 for the model range and MFI. Then once in MFI go to ECU information or Special Function->ECU Information and copy all the info there.
The Launch is not likely to have what we need... last I checked it only would give the ECU part number which is not sufficient. We need the software version etc.... the Euro MUT should still read this as long as you go in generically (don't try to go by VIN or it won't work).
I don't know if the MUT2 will work as it is more model-specific ironically enough. The MUT2 makes you select platforms/engines/etc whereas the MUT3 is smart enough to be able to figure out the details on its own based on the protocol as long as they select the "old" model range (should be "up to" 2005 or so roughly). The MUT2 could do the same thing, but it isn't configured to do so unfortunately. They could select a Pajero as long as there was a 3.5 non-GDI model in your market for 01 era.
The 3.8 shouldn't have come out until mid 2000's.... that engine wasn't out of development until early 2000s. But even at that, the 3.8 would probably work for reading the ecu anyway, same protocols on the 3.8 vs 3.5 engines.
yeah thats right about the flashes for sure.
Lets get those fresh O2s in the front sensor positions and if that thermostat is an over-cooling one get the proper 88C one in there and then we can regroup.
Worst case scenario... keep in mind if you do that you are going to have to rely on them to program your keys too which they may not be able to do.
Yes, but when you buy a new ecu you will have to get your keys programmed to it. The immobilizer key data is stored in the engine ecu. So until that is done, the engine won't run.
They may be able to go in as another type of vehicle from the same era to program the keys, I'm not 100% though.But yes... a new ecu would be at the current software level with all updates.
That's a different situation but not better/worse.... maybe worse. You would have to swap the ecu, the immobilizer ecu and the keys/lock cylinders if you went that route. As the used ecu will have the old trucks keys stored in it not yours of course. And you can't move the ecu without the immobilizer ecu at the same time; if you mix/match the car won't start (the two ecus "marry").
No problem, I'll be here.
It should be the same size, but I would not use it....that's a 10F degree difference which will cause problems I can guarantee. That is a popular one around here (I'm in south Florida) and it does trip faults etc.You shouldn't have any issues with over heating really unless you have lots of sitting idling, in which case adding better fans would be a smarter approach than lowering the thermostat. Unless you are OK with the engine light being on of course, in which case you could go with the lower thermostat.
The lower stat should set a P0128 instead of P0125 which won't affect loop changing, and so won't affect shifting. The P0125 is more related to the O2 sensors than the coolant temperature.
Not really. Be prepared for some gas to spill when you unbolt it, thats about it. The new regulator should come with an oring on it already, you can wet it a little to ease installation (gas, water, silicone, whatever).
No problem.... and just to be clear, a silicone spray lubricant not like silicone caulk :)
And again even water or some gas is fine too. Just something to make it slide in a little easier.
The biggest problem child with O2 sensors are Boschs. They pretty much never work.
The P0450 shouldn't have any relation to these sensors at all... it may have just been a fluke that it set, or it may just be real intermittent. We'll see what happens.
Not really.... Unfortunately there is a dead zone in the middle there where you just don't get what you pay for when you are over $100 but under $3000.
If you had to choose, I would say look for a used Autel 805 or Launch X431. Both are often in the ~$1000-1500 range new, so used can be found for half that or less if you are lucky.
Neither are terribly great, but they should have two way communication and a lot more functions than your basic code reader etc.
Certainly possible. I'm still not sold on that sensor being bad, but if you go in there again lets check the voltage on each pin of the sensor with the key on.
The sensor will wobble a little, not a lot though. It is just an oring fitment and on an 02 I believe it snaps in (no nut holding it anymore). As long as it isn't flopping all over it is OK... a millimeter either way etc is normal.
Pin 3 should have ~5V when unplugged, it is a green/red wire. The other two wires are grounds (one fixed ground that is black, one PCM ground which is blue/yellow).
Yes that is absolutely possible regarding heat on a worn pump. When the pumps start to fail they generate more heat, the more heat the higher the resistance, the higher the resistance the slower the pump speed and so less pressure, less power.
Sounds good. If you have 5V on that wire, plug the sensor back in and then back probe the blue/yellow wire (other lead still on ground) and see what sort of reading you have.
You don't need to worry about that... just no smoking while you do it, etc. There isn't enough voltage there to do anything dangerous.
No problem at all. Keep me posted
Hi,Did we get a fuel pressure regulator for your fuel rail or did we just talk about it?
Hmm.I'm a bit unsure of what to think about it running lean still. That is generally going to be either fuel related (low pressure/volume) or intake leak, or in lesser quantities an O2 fault.
I'm not sure what you are describing regarding the connection below the purge solenoid... could you get a photo?
Yeah that would be odd to see the injectors cause it but technically it is possible I suppose. Normally you would expect either a rich fault (if they were leaky/flowing too much) or a misfire if not flowing. Usually anyway.I'd be looking over for intake leaks again.
Yeah that purge valve if it is passing air at rest it is shot... and that theoretically could spike your fuel trims (usually it sends them rich to negative percentages, but it depends on a few things if that happens).
That said... if the hose for the purge (or ANYthing) is missing, it is likely to suck air and will cause your fuel trims to go lean.
LTFT can take 4-8 minutes to cycle. So it is not unusual to see it change after certain driving. As long as you are seeing it drop below 10% you are in safe range... ideally you want to be +/- 5-8% tops, and it can go either direction. It is when it starts hanging all positive or worse maxes out (12.5) that there is likely a leak somewhere etc.
Yeah it is going to be available locally I'm sure. They are used on a ton of vehicles per-design. The hard start with the full tank makes perfect sense if that purge solenoid is leaking too, because it is drawing fuel vapor in which when the tank is full is overwhelming to the engine. It can take a long long time cranking to overpower that (or sit an hour for it to dissipate).
Yes, that is the vent side of the PCV.
No problem... cable service came back a few hours later last night, but I had already given up :)
Keep me posted.
I'll be here!
The most common are the two gaskets, throttle and plenum and having a hose failure. The hose behind the throttle body (facing forward) that goes to the fuel pressure regulator is probably most common to get knocked off or forgotten etc.
No the IAC position moves based on ambient conditions and engine temperature. It does not change in correlation with the throttle at all.
Bummer on the 441 pending, but at least we know that isn't an issue. Whats the story on the purge valve situation? Remember the evaporative system needs to be sealed perfectly to prevent faults, if that purge may be leaking still even in minuscule quantities it will cause an issue.... not to mention the full tank hard start situation if it is bleeding vapor in.
First picture...If you are talking about the hose on top of that diaphragm, that is the cruise hose that goes off to the cruise pump on the fender area. When cruise is active the pump draws vacuum on that to open the throttle.
Second picture the EGR and purge hoses look perfect.
Third picture, nothing much to see, but the vent valve there dumps to atmosphere.
Can you get a better photo of the area you are concerned about?
Ah no worries
Cool, keep me posted!
Driver side cylinders front to rear are 2-4-6. Passenger side cylinders front to rear are 1-3-5.
Standing in front of the engine looking at the coils, they go 5-2-1-4-3-6.
Yes that is right... the last two coils have the numbers transposed, but it doesn't really matter (each coil fires both leads at the same time).Also if you look on the intake plenum it will usually have the numbers marked there behind the coils too.
How'd the gaskets look? Also you see the 5-2-1-4-3-6 on there now? :)
Oh man those gaskets look trashed. Lets get fresh ones in there. These gaskets can usually be reused once, but after that two things happen... the embossing on the plenum gasket can lose its shape which affects sealing and the black coating will start to flake off which will cause leaks. You are definitely missing large chunks of that coating on the plenum gasket.Lets get both of those replaced and see what's what.
I would perhaps try taking those hoses off the purge solenoid and plugging them solidly so neither one can pass any air at all then see if the hard start remains.
MR552792 Looks to be correct for the vent valve on my end.Let me know what happens.
Fantastic on the lean code!
The weird evaps are going to be it... what is the status now on the purge solenoid (the one behind the throttle body, next to the smaller egr solenoid)?
No problem. We just want to make sure that the purge solenoid does not pass any vacuum at all at rest, and the vent solenoid (on the fender) passes air fully at rest. If either are remotely questionable we definitely want to change them.Keep me posted!
For the purge we really need a hand vacuum pump to verify... blowing through it is not sufficient, as it can have a leak that drops an inch of vacuum a minute and cause problems... you need to be able to see 30inHg of vacuum held indefinitely to know it is good.Hopefully that will square some things up... I can't really think of anything that could have happened during the filter replacement that would have caused an issue.
If the purge valve is leaking slightly, depending on fuel level it can run rich (if tank is near full) or lean (if nearer empty). The vent valve won't really affect it much as if it seals at the wrong time the evap system just won't operate... it is normally open anyway.
I'll be here :)
If you mean the restrictor on the EGR solenoid hose, no it won't affect your situation. That is sort of like a last ditch filter to keep carbon out of the solenoid more than anything. We often remove these to diagnose EGR faults, as they are the most common cause of EGR malfunction having that restrictor clog so we put a regular hose in its place and see if the problem goes away. To get it you need to get the hose... which last I saw you couldn't get anymore so a used one would be it if that is still the case. All Mitsubishi restrictor hoses will have a white stripe on them normally, you just have to feel along the hose for the bulge in it if there is more than one white stripe hose (if for example there is a pipe in between two sections, feel both to figure which one has the restrictor).
It would not have any relation to the evap system whatsoever, though.
Yeah no worries on that. It is best to be there as in addition to a filter of sorts, it also reduces the speed at which the valve opens... It doesn't do any noticeable change though in most instances though. Generally speaking when I have people that have EGR insufficient flow faults and I have them swap the restrictor hose out to verify the fault goes away, most of the time they just opt to leave it the way it is once confirmed fixed without it. I think it is something you probably notice more on a smog test than seat of the pants.
Hehe... I bet that purge is leaking like you saw initially. We'll see when the new one gets there.
As long as it is the two hoses on the solenoid it shouldn't matter too much; the solenoid just opens/closes flow. Use the orientation on the one I sent you though, remember this was the one that had the updated chart.
Keep me posted
Nope, plug and play! Swap it out and clear the code and you are good to go.
Bummer... our primary speculation on the purge was you having been able to pass air through it. At this point a smoke test would be ideal as there is likely something amiss with the hoses/tank connections/etc.The leak... check the metal cross over pipes etc back there, they are real common to rust through and leak.
There are home made ones you'll see on youtube using usually mineral oil and some sort of heated tank set up. Not sure if it is worth going to that extent or how effective they really are though.
If the water leak is literally right at the throttle body, suspect one of the two throttle body coolant hoses. If you can get a photo of the region it might help out... if you are not able to see the actual origin with any success you can put a cooling system tester on there, they just seal to the radiator neck and have a hand pump to pressurize the system.... with a few bumps your leak should start shooting out like a jacuzzi jet and will help find it. Just be sure it is cool when you do that so you don't burn yourself.
The vent valve... if you can blow through it at rest and a hand vacuum pump holds indefinite pressure when energized, the valve is good.
For the smoke you would hook up to the vent valve port and that will fill the system (remember it is open at rest).
Definitely could be that hose/clamp. The port where it attaches on the throttle looks pretty corroded. I would check the clamp is tight, if it is, then loosen it and slide it off and inspect the hose itself and the port etc. Could be a pinhole in the hose or just bad sealing due to corrosion. Obviously if the clamp is loose, try tightening it first.Looking at the other end of that hose though you can see the main cross over pipe... and you can see rust forming and possibly even some coolant staining. That is one of the three pipes that typically rust out on these, so I still would not be surprised if it leaked. The pressure tester will help find it though (or running the engine to pressurize... just again, watch the temperature that way... the pump/tester you can do while cold).
Yeah the tester with the hand pump is probably best here as you can put it up to 20-30 psi then usually (whereas the radiator cap bleeds off pressure around 17 I think).
I wouldn't go getting concerned about component failure on the throttle or anything like that yet... the hose looks rough, the port looks rough, and the pipe behind it looks like it is about to rot right through. You have a lot of more likely suspects here that are all super common.
I don't believe the cooler housing is detachable on this model. On others it is, where the servo and the housing are both separately detachable, but the 01-02 Montero I'm nearly certain it is not... and looking at the parts catalog there is no gasket listed, so if it is detachable, it isn't meant to be serviced.Again.... I'd be highly surprised if the problem isn't hose, corrosion on port, or pipe rust related. This is a weekly thing we deal with on these, I have never seen a single throttle body leak coolant due to defect in the unit... if rust/corrosion isn't related, it isn't likely the case here either.
That actually is what would happen if the vent valve was shut... tank would pressurize when it shouldn't, and pump would cut off early. However again if it was passing air through at rest it should be OK (And of course closing when energized), however I suppose there could be a partial blockage in it or something.
Well more to the point partial blockage meaning it isn't open fully. The problem would be mechanical and not electrical if that were the case since it is normally open... unplugging wouldn't change anything there.
Well again we should be able to test is with a hand vacuum pump and rule it out just like the purge valve.
There is no replaceable gasket there as this throttle body is not meant to come apart... if it really is leaking there, you need a new throttle body as far as Mitsubishi is concerned. You could try taking it apart and using a coolant-friendly sealant (like DP300/Blue etc) since you don't really have anything to lose there.
I need a VIN for the throttle body, as there are multiple options for this year.
Yeah you're going to want to find a used one if you can't fix that.... MD357261, $950 list.
Yes, it will come with a new genuine IAC and TPS as well as cruise diaphragm.
The TPS will be pre-calibrated. The IAC should be calibrated, however I have had a few of these recently that I had to go into the scan tool and do the SAS calibration again. It all depends on how sealed up your intake is too... if there are slight leaks it can affect IAC calibration.
They should all have cruise, I'm not aware of a model without it this generation (at least not a US model). The other throttle listed for this year is $100 more, no idea what the difference is.Let me see if I can source a bare housing.
You could get a bare housing (no sensors, no cruise diaphragm, no bracketry etc), however it is discontinued/obsolete with no inventory in the US. If you want to look locally it is part number MD628125... it listed for $500 even when it was last available.
I don't know what you mean blocking the valve. If you are talking the vent valve, bad things will happen.
If you mean the idle valve and the coolant etc... you can take the two hoses to the throttle body and loop them together to bypass it so the coolant never reaches it to leak. There is no real impact doing this... they are only there to help warm up the throttle body faster in cold weather.
Yeah just loop the two coolant hoses going to the throttle (or cap the ports on the coolant pipes) and no more coolant in the throttle body, no more leak.Do not mess with the idle valve itself. If you do it will run like garbage. The valve has to stay there to operate, you just won't have any coolant running through the housing.
Right, the cooling portion has nothing to do with its operation, just proximity. Yep any union between the hoses will be fine or cap the ports on the coolant pipes.The idle valve will not behave any differently. You are over thinking the situation... the coolant is just there to get the throttle body up to operating temperature faster in sub zero temperatures etc.
Exactly. And yes you can leave the throttle body ports open as they will just do nothing. Then either loop the hoses or cap the ports on the coolant pipes.
You won't even notice it though. It is literally for freezing temperature conditions only.
Yeah that cooling system modification will only affect you in below-freezing temperatures, nothing else.The smoke you will induce at that vent valve to fill the system. It needs to produce enough pressure to fill the system, then just look for leaks. The fuel tank area is going to be your most likely suspect for external leaks.
Just hook it up and let it run a bit, then take one of the vapor hoses off (or gas cap) and see if smoke exits... if it does, then that is sufficient and you just need to search for the leak. If you don't have smoke in other areas like when you take the cap off, then it is not producing enough pressure to fill the system.
I'm sorry for the delay. I had a medical issue that has be stuck in bed at the moment, this is the earliest I've been able to check in.
It may be worth the time to drop the fuel tank and inspect everything visually as best you can.
Well without a good smoke tester and having ruled out the purge and vent solenoids, its really going to be hoses somewhere most likely (or rotted metal ports on the tank etc).Oh yeah... you have to use the metal gasket. The paper ones will cause issues for certain, if not immediately, then down the road (the oil erodes them).
There isn't that much.
The pressure and return lines have fittings at the front edge of the tank (there are hard pipes mounted to the tank from there to the pump). There is I think one other vapor line at the front and three at the rear, and of course the filler neck lines.
I'll see if I have a diagram.
This isn't the best but should give a rough idea of what you are working with.
That is pretty weird. It can take dozens and dozens of successful evap tests to clear the code, so I'm not sure why the light went out. The pending code always sets on the first failure, then the light turns on at the second failure.
Yeah just keep an eye on it. If it seems relatively consistent doing that, perhaps we should re-test the vent valve.
Might be worth a US order, I'm sure there are ones available in our warehouses. You want to avoid aftermarket with those anyway... while I haven't seen issues on that particular one, the purge and EGR solenoids are famous for aftermarket ones leaking brand new.
Let me check that again
Wow its limited, but it is available.Using VIN JA4MW51R21J024011, the vent solenoid is MR552792. There is one of these in the New Jersey warehouse, and three dealers (Massachusetts, South Dakota, and Washington locations) have one each in stock.Not real great, but any dealer that orders it will get that one in New Jersey unless it is an accounting error. And at that, they can do a dealer-to-dealer transfer from one of the other dealerships if the other dealer in fact has it and will let go of it.Ordering will be delayed accordingly, but you should still be able to get it. If you want a new one, I would try ordering from Mentor Mitsubishi and see what they say. With only the one available they will likely call the warehouse to confirm its existence first anyway.
Oh yeah that's weird. If it does that you can still go to another dealership site and order it still (mitsubishiparts.net etc).
It is definitely designed to run there, it will do better and won't throw any warning lights that way. If you have local climate related issues you may try an auxiliary fan, but honestly they use that rated thermostat around the world, your cooling should be fine.
The passenger side should have room unless you have an auxiliary tranny cooler option. In either case you would usually ditch the condenser fan for a larger higher flow fan and rig it to work all the time rather than only on high AC load.
Yeah that's normal temperatures for most vehicles these days. The engine is more economical and cleaner burning in the 200-220F range, that is why most modern cars will have thermostats that start opening at 195F and cooling fans at 220-235F. All about the penguins.
Yeah I don't know why they would have that apart from for some other vehicle... or perhaps they have ECUs calibrated differently there (so it doesn't throw a fault when it over-cools). No clue. There are only a few different physical sizes though, so it is very possibly for some different vehicle entirely too.
Weird, it should have.Why did we change it again?
Gotcha... we've been on it for a while, it gets hard to remember :)
Gotcha, that explains it.
As best I can figure from the parts illustration (they are not always terribly accurate since they reuse these for different models sometimes):
The "c" connection on the end should go to the engine; the "e" connection in the center should go to the fuel tank, then the unmarked port on the top end (of the picture) should go to the vent valve.
That sounds right, the bottom port should be the "middle" when looking straight down at it (it is slightly offset from the other). If that is where it is, its fine.
As above, the one that is centered when looking straight down at it should go to the fuel tank; the one on the end should go to the engine.
The whole system is suspect when it comes to a leak. There isn't any one section/line that would be it etc... the whole system is placed under a vacuum, if the vacuum fails, the code sets.
The long cranking... when it is related... is usually due to vapors going into the intake. We would normally expect a purge solenoid or hoses reversed etc when that is the case, but both of those are ruled out. When it isn't related then it is usually fuel pressure.... either weak regulator or weak check valve in the pump.
The check valve is part of the pump module. The easiest way to check that condition is to hook up a fuel pressure gauge to it, run the engine, then shut it off and see if the pressure bleeds down more than 10% or so.
With it only happening at full to half tank though, I'd be more likely to suspect evap related though.
Sorry for the delay, I've been out of town all day and just checked in to see if anyone was waiting before calling it a night.
Use the chart I posted earlier with regard to hose connections. It is real hard to get them mixed up anyway though as the sizes and connections are fairly different on most of them, as well as the routing will be relatively rigid from age making it feel unnatural if you try to reach one to the wrong location.
The evap leaks are extremely difficult even with the correct tools; without a good smoke machine and having ruled out the common non-leak related causes, its going to be extremely difficult as I mentioned before. Even dropping the tank, we would be hoping for an obvious issue like rodent nibbling signs on a hose etc. A pin hole you aren't going to find without smoke etc.The evap system on the 3.8 is similar in operation as the 3.5, but the locations are significantly different. The design is nearly identical in principal, just different in execution.To tell if deleting the system will fix your hard start? Go to the purge solenoid on the engine (behind the throttle body, the one with the two larger hoses) and remove the hoses then plug them WELL so they can not leak. That will block all evap operation from the engine... if the hard starting is still there, then I would expect a fuel pressure issue like we discussed before. If the hard starting goes away.... then yeah, its the evap.The only issue with deleting it is I don't believe there is going to be any way to get the light out as I don't know of anyone that has decoded these ecus to be able to do that. Perhaps someone has, I am not aware of it though. Apart from that it won't affect anything to be removed/disabled. All it does is periodically use engine vacuum to place the fuel tank under vacuum and make sure it holds vacuum (indicating it won't leak gas or vapor into the atmosphere). It is 100% a verification of no emission only... it doesn't help/hurt drivability in any way, just a "Check" system.
The big thing is the side going to the engine is sealed off, so the engine can neither suck in vapor or fresh air. The other side is only capped to prevent anything from getting in, but doesn't affect the "test" so to speak. Like you said, it can't get to the engine, that is all that is important.
With regard to the fuel pump... if you changed out just the pump motor and not the pump module, that can still be pump related if it is bleeding back. The fuel pressure test would be in order to verify. There isn't really anything else to suspect with regard to hard starting like that... it is going to usually be either vapor related or fuel related in some capacity.
On the fuel rail there are two lines going in.... the one with the metal can and the two hoses (one liquid one vacuum) is the regulator side. You don't want that side. Take off the other side which is the high pressure line and put the adapter in between the pressure line and the rail then hook up the gauge. Run the engine so the pressure builds like normal, then turn the key off. It should not drop more than 5 psi or so. Give it 30 minutes or more and recheck... it should not lose hardly any pressure. Let it sit as long as possible.... it should not lose more than 10-15% pressure normally even after hours. If it drops considerably, there is either a regulator, check valve or injector leaking pressure. Since the regulator is new that is unlikely, and an injector is unlikely in general.Normally this would not make any difference with regard to fuel level when it caused an issue, but is worth checking out anyway since you bypassed the purge line and still see an issue.
The vent is part of the evap system... if the evap is unable to run it really shouldn't be an issue as any other vent related problem would be with the filler neck vent pipe, and that should cause difficulty getting fuel in if it is clogged.
Hi,I would agree with everything regarding the ignition module (power transistor, technically). They can cause hard starting when they get hot specifically. Usually it ends up dropping one or more coil outputs when that happens.
Yes, the check valve is part of the pump module; if you change out just the pump motor with an aftermarket for example, the check valve is not changed. If you always start up fine in the morning, the check valve is not the issue. When they fail then you will have hard starting after sitting over night.
Yeah again if it starts fine in the morning, check valve is not the issue. When they fail they bleed down pressure over a long period of time like over night, causing hard starting. Literally the opposite of what you have from the sounds of it in your previous comment.
It would be unlikely to see the pump relay fail. Possible, but unlikely.