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Doug
Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 8538
Experience:  Mitsubishi employed and Factory trained ASE certified technician
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Changed fuel pump in 2000 mits eclipse, had to change

Customer Question

changed fuel pump in 2000 mits eclipse, had to change connector too as it was burnt. Pump works when cranking engine but car won't start, no fuel flow, disconnected line to check while cranking.
Submitted: 1 year ago.
Category: Mitsubishi
Expert:  Doug replied 1 year ago.

Hi,

The pump should only run while cranking, so there is no issue there.
With regard to the fuel flow you didn't mention where you unhooked it if at the engine or the module... if you remove the hoses (both) from the pump module and crank the engine, do you have fuel exiting the pump module?

Customer: replied 1 year ago.
I checked and I am getting pressure at the pump. Disconnected the flex line at inlet to fuel injector rail next to throttle body under front hood. Put a can under it to catch any flow but there is no flow.
Expert:  Doug replied 1 year ago.

Thanks.

So when the lines are off the pump, the fuel comes out of the port with the barb that has the locking hose, or the thin port with the hose clamp?

Expert:  Doug replied 1 year ago.

And when it comes out, does it come out like a firehose or like a garden hose?

Expert:  Doug replied 1 year ago.

I tried to take your phone call request, but the site said there was a problem preventing it.

We should be able to resolve this here without too much issue though.... we need to know first if the flow is coming out of the hose clamp port or the locking port on the pump module to make sure the pump is flowing correctly; second we need to know if it is a high pressure flow of gas or low pressure like a garden hose.

Customer: replied 1 year ago.
There isn't enough room to get the pressure side fitting off, the one with the two tangs you press in to take off. But I was able to get it partially off and fuel sprayed out under pressure. Didn't disconnect the second line. The pump was replaced on Thursday and I drove the car home it was fine. The next day it wouldn't start and I could hear that the pump wasn't working. My mechanic told me the fuel pump electrical connector was in bad condition and needed replacement. Today went to junkyard and found a very clean connector. which I soldered onto the car harness and sealed with shrink wrap tubing. Pump runs fine during cranking of engine but won't start, no fuel out of line at injector rail.
Expert:  Doug replied 1 year ago.

Thanks.
So the pressure is on the correct side of the pump, that is good.

When you checked for fuel pressure at the engine, did you check at the port that is held on with two 10mm bolts, or the port that has a hose clamp on it?

Customer: replied 1 year ago.
The port with the hose clamp. That's probably the return to the tank, didn't think of that.
Expert:  Doug replied 1 year ago.

Absolutely right... that's the return, which will only give you fuel (out of the port too not the hose of course) if you push over 50 psi, give or take. And at cranking voltage (10.5-11V typically) you aren't going to see that much pressure so nothing will come out.

So at this point we would want to check the pressure hose at the rail if we are suspecting a fuel problem, however if you have good pressure at the pump, it is only straight hose to the rail so it is unlikely there is a problem there (no filter to clog or anything).
Never the less, I'd say since it is an area of suspicion lets pull the pressure line off and see if you have good strong pressure there while cranking. If you do then we will need to approach this entire situation differently of course.

Customer: replied 1 year ago.
Loosened both 10 mm headed bolts on fuel supply line to rail, no fuel out of line during cranking! This doesn't make sense, if there is no filter and its just a line from the pump to the bolted flange what would stop the fuel ?
Customer: replied 1 year ago.
Car computer has no fault codes either, checked with my reader.
Customer: replied 1 year ago.
My son just came home and found a shredded electrical lead on the RH side of the motor, heard it was an issue online, goes to sensor for MFA or MFI something to do with the fuel injection system. Will let you know more tomorrow, too cold and dark to work now. Thanks for your help.
Expert:  Doug replied 1 year ago.

Sorry for the delay..... when the pump was changed they didn't drop the tank did they? Perhaps created a kink somewhere?
The run from the pump to the bolted line is a straight run, there shouldn't be any filter on there for a 2000+ model.

Regarding the shredded wires... if it is the crank sensor (up the center of the engine by the belts) this is common to be cut by the belts if it is not secured... it should prevent any operation of the fuel pump though if that were it. The crank sensor is what turns the fuel pump on, so unless you are just getting a prime and not pumping while cranking, that wouldn't add up.
Look into the crank sensor wire tomorrow and see if that is what he was looking at... if it is, repair the wiring and lets recheck.
I will be in most of the day tomorrow.

Customer: replied 1 year ago.
Not sure if your around today but another big disappointment. We fixed the crankshaft sensor lead by shortening the lead and splicing with crimp connectors and shrink tubing it looked fine. Tried to start but no luck. Do the injectors need to be bled? Also no fault indications. Mechanic did not drop the tank to my knowledge but will ask tomorrow.
Expert:  Doug replied 1 year ago.

The injectors do not need to be bled.... just cranking for a few seconds will get them done since it is a return type system.

I think it would be best to see if you can hook up a pressure gauge right at the pump and see exactly what sort of pressure is coming out of there. If it is less than 50 psi or so while cranking then we still have an issue with the pump. provided again the pump is running... we do see three major issues with the pumps on these that all revolve around aftermarket pump motors... first, they are usually very low quality and fail very quickly; second, it is not uncommon for the o-rings to not fit properly or get lost during the swap and cause pressure bleed off internally; third the factory pumps rarely fail, what does fail is the connector where the harness hooks up... the inside of the pump module where those wires pass through (well, metal pins) deteriorate and result in very reduced current to the pump motor, which of course replacing the pump motor does absolutely nothing for, it requires a whole module.

I would see if you can get a pressure reading at the pump... if you can not or it is very low, try hooking direct power and ground to it rather than relying on the factory wiring to see if it changed. If you still have low pressure there then you are likely to need a new pump module.
If you have good pressure (~50 psi) at the pump port while cranking and nothing exiting the pressure line at the engine (again the one that bolts right to the rail, not the one with the regulator on it), then there could only be a blockage in the line unusual as that would be.

If you do not have any pump operation to speak of but hooking power up manually you do, then we would want to re-evaluate the vehicle... specifically testing the crank sensor (it is common for them to short out when the wiring gets cut), checking for spark and fuel pulse, etc.

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