1998 Eclipse GS Fuel Pump Overheating - Help me if you can

eclipse
mitsubishi

#1

We will start with the history. I recently purchased this car knowing of a long list of issues which have been worked out for the most part. The related piece would be random misfires which I believed were based on a faulty Ignition Coil (common on this 420a [2.0 NA] motor.) I have replace the coil but the issue persists.

Now what is happening is after about 20-30 minutes (or miles) of driving the fuel pump will overheat and the car will stall. I can get it to turn back over most of the time but it will stall out if attempting to drive. I have to leave it sitting for about 15 minutes to be able to move it.

What codes am I getting from the CEL? Nothing. (No CEL)
What have I tried so far?

  • Fuel pump has been replaced
  • Fuel filter has been replaced
  • Fuel lines have been verified (no noticeable leaks, unwanted bends, pinches or breaks)
    (I also verified that this is not an issue with the PCV valve or EGR [electric in this car] valve)

I know… I thought relay or wiring also - but all lines and the relay are cool to the touch so they are not overheating.

If anybody out there has some input as to what may be causing my pump to overwork itself - I would be forever in your debt. At this point I am throwing part after part at an issue that seems to be a purple unicorn. It also isn’t a lot of fun to hot swap fuel pumps in the back seat of your car on the side of the highway so this can’t be a long term scenario for me.

Thanks in advance.


#2

How do you know that the fuel pump is overheating? I can’t imagine a fuel pump getting overheated in a full tank of gas.


#3

The car stalls out. If you let it sit for a few minutes it will run again. Plenty of spark, plenty of air. No fuel.


#4

That sounds like a bad circuit. Are you sure all the haness connections for the fuel pump are clean and seated properly?


#5

When the car stalls out, what is the voltage on the fuel pump power wire. It is possible for the fuel pump relay to fail intermittantly. Ohmic relay contacts will not necessarily overheat the relay. So check the voltage at the pump

Can you hear the fuel pump when it is running.? Is there no sound when the car quits? Put a fuel pressure gauge on the high pressure side and wse what the pressure is doing.

As missileman stated the pump is cooled by the fuel flowing thourgh it. So the only indicator of an overheating pump would be boiling of the fuel.


#6

I can hear the pump while driving. I left the back seat out and the panel cover off for that reason. After the stall - with the key in the run position I can hear the pump prime, however it won’t always start - if it does - ruff idle and then stall until it has been allowed to cool off.

I haven’t been able to check the voltage on the line after a fail at this point. Its rough to get your car to fail in a “good” spot if you know what I mean. Seems that the general idea is relay or the harness itself though. The harness is connected well - but could be failing.

Any chance this could be related to an issue at the injectors/fuel rail/ injector harness?


#7

I also have to think the trouble you are having is due to a faulty power connection to the fuel pump. The most logical suspect is the relay. I wouldn’t rely on feel to determine the relay condition. You need to use a volmeter to check the power getting to the pump motor.


#8

Replaced the relay today. The issue persists. What else could cause a stall - only when hot?


#9

Thank you all for the input - however I will be killing this thread. I have successfully ruled out fuel and air from the triple threat of things needed for an engine to run having isolated the problem as spark. My new issue is - why is it not getting spark. I have started a new thread for the correct issue moving forward. Again - Thank you all