Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Yes I have tried the test with a helper as my wife turn the key on and I'm at the fuse with a volt ohmn meter I get no power there. at the connection to the fuel pump by the tank I got power to fuel gauge but not the pump. I've allready droped the tank and checked the pump and wires they are good. I can hot wire the pump via the fuel pump fuse on fire wall and hear the pump running. also loosened the fuel ine at the throttle body and both sides of fuerl filter and will spray gas. I checked al fuses at the fuse block in the dash, and they are all good. I'm so lost as to my when I turn the ign. on I don't get power at the fuel pump fuse. I can hear clicking when I turn on the ign. and the relay is brand new. Is there any thing else to check and locations would be helpful. any other info you might need let me know. by the way where are ign. 0 and ign. 1 located so I can make sure that I checked them.
Thank you so much for your advice.
I do not have a wiring diagram, That would be helpful. [email protected] is my address. No burnt or corroded connections at the fuel pump relay. One thing I did find, that might help, is I have power comming into the relay, but with the ign turned on I cant find any power on the other wires comming out, just that one orange wire is hot with the ign. on or off. The relay is new from NAPA.
INJ fuse and ECM-INJ fuse are they blade fuses? are they located in the fuse block in the dash? I checked all fuses in the fuse block in the dash and all have power.
If you are still in need of help let me know and I will see what I can do to assist you
I was looking at the other posts and either dont see it mentioned, or am overlooking it-what size engine? Is it a TBI or CSI engine?
Check for power at the orange wire and at the dark green/white stripe wire that go to the fuel pump relay and let me know if there is power at both wires or not
I have power comming into the relay,orange wire, but with the ign turned on I cant find any power on the other wires comming out, just that one orange wire is hot with the ign. on or off. The relay is new from NAPA.
Ok, the orange wire is battery feed. The dark green wire/white stripe is the fuel pump relay control signal from the ECM. If that wire doesnt have voltage when key is turned over to crank vehicle, the fuel pump relay isnt energizing.
You are going to need to check for voltage at the pin itself at the ECM for voltage going out. If none going out, ECM is defective. If voltage present, then there is a short/open in that wire that will need to be traced:
Ok- let me know what you find.
The ECM is located behind the right side of the dash near the blower motor. Remove the glove box for easier access
Ok, will be here all day tommorrow
Ok, that is what controls and enrgizes the fuel pump relay. No power there means either a fauty ECM or a short/open in ECM. To further test the ECM at this point to verify its bad is going to take a factory level scan tool that can operate the different functions of the ECM for testing purposes, but based upon not having power at that pin, odds are that the ECM is faulty
Let me put the brain cap on and see what I can come up with...this one is a bit strange
You havent mentioned anything about the oil pressure gauge not working, so I have assumed that it does. Does the oil pressure gauge work?
as far as I know. I havent had it running long enough to see what it is, as the fuel I pour in the TB gets used up rather quickly.
Anyway you can get some one to feed TB while you crank it and see if oil pressure gauge is functioning and let me know? There is a reason for this- the oil pressure switch acts as a secondary fuel pump relay.
Ok, in the meantime, I will keep checking into this
Ok, that eliminates the oil pressure sending unit/secondary fuel pump relay.
I am going to call a buddy and run this by him and see if he has a clue, as I am stumped right now. I will get back to you - probably be an hour or so
I wasnt able to get a hold of my buddy until today. He was going to check some things and call back. Justing waiting to here back. I emailed him a copy of our posts, and he had the same thought as me- bad ECM. He was initially stumped as well- he is leaning towards a short/open but wanted to review the schematics and see if he could narrow it down.
I havent forgotten about you.
Have you checked for power at the injector harness connector? Does it have 12v at one or both terminals?
Have you tried applying 12v to the fuel pump test connector(located at firewall behind brake booster)? If you have, did the fuel pump run?
Ok, try that and let me know. That will help narrow down area and potential wiring to test
sorry reread your question and see that I need to apply power to it. still want to know if it's under the hood or under the dash?
Sorry, gave you wrong diagram.
You want to apply 12v(can use a jumper wire from battery) to terminal G in the DLC(data link connector), located under left side of dash, just to the left of steering column:
Ok, there is an open in fuel pump relay drive or power circuit, or faulty relay. You have replace relay, so you will need to test wiring between ECM and relay.
I unhooked the ECM and the fuel pump relay, I attached a hot wire to the dark green wire with a white stripe and checked the same wire at the relay connector and it is passing power. that wire is good. scratching your head yet?
Yeah, just deleted a post on reading this. I was going to get you to run a wire overlay for the fuel pump relay to pin #F6 at the ECM
Ok, there is not power at the darkgreen/white wire. there is power at the orange wire
Ok, lets do a wire overlay. Run a new wire from the ECM pin #F6 to where the dark green/white wire goes into the fuel pump relay. For now, just run it as temporary wire the easiest way possible. If fuel pump energizes, then we know the open is in the dark green/white wire.
if there is an open in dark green wire between the ECM and relay, then although there will be power at the ecm, there is none at the relay. So by running another wire between the 2, we are giving new route for power. At this wire, you will only have power for 2 seconds when turning the key to the on position.
Check for power at pin #F6 at the ecm. With connector connected, backprobe that pin for 12v during first 2 seconds when ignition turned on. That confirms ECM is sending power to the relay. Now, check for 12 during first 2 seconds when ignition turned on at the green wire at relay- no power confirms that voltage is lost between the two, so we know there is an open in that wire.
We run a new wire, theoritically we should have power during first 2 seconds ignition is turned on to the relay.
possible bad ground to ECM or a power supply issue to ECM, but then it wouldnt run when you pour fuel into it...
My buddy's thoughts have been the same as mine.
Let me beat my head against a different wall and see if any new thoughts pop out...
You're not... we always come across the vehicle that seems outsmart us...just takes time- especially on electrical problems...
I am still looking into it. Havent given up yet. I have ordered a different set of schematics to see if mine are missing something. Should be in Mon
Ok I tested the 740 orn- wire got .5 volts, and 639 pnk/blk- wire and got 12 volts, with IGN on per instructions you sent. Not sure of the voltages are what should be there, but it states that it could be faulty ECM or ECM ground. The ECM is brand new from advance auto parts, with the original PROM installed. They don't give a new PROM with a ECM purchase. If the voltages are ok then what is the next step in trying to fix this issue? Also I don't have the service engine soon light, but there is a check gauges light that stays on. Don't know if that helps any.
Is this what is called a crank sensor? or do I just ask for pickup that goes in the distributor. Thank you
You should ask for the pickup that goes in the distributor; this will be cheaper than replacing your distributor and hopefully this will fix your problem :) If not, let me know if I can be of further assistance to you; I will be happy to try and help. Regards, Howard
Okay, what you replaced was not the pickup. I have researched it to be able to give you a visual of the part. Go to e-Bay and either search by auction # XXXXX or type in under search "ignition pickup chevrolet c1500". This way you can even print it out so you make sure you get the right part. Advance has this part online in stock (I already searched it); you can go to www.advance.com and it is part # XXXXX I know trying to do this online is rough :) P.S. Don't buy the dynamite!! LOL!! Let me know how THIS goes; I'm here.......
ok. I replaced the distributor, it had everything new with it. still the same problem.I've spent 28 for a fuel pump relay, 120 for an ECM, 30 for a control module, and now 130 for a distributor,cap rotor button. so at a complete loss. and besides that I think I got the distributor one tooth off. do you know where I can find some cheap dynamite? LOL
I don't know what else to do.