Ex won't start....sometimes.

[pepsiking]

I have an on again off again problem. Sometime when I go to start it I don't hear the fuel pump prime. When this happens it won't start. At first I was thinking the fuel pump was going out but once she starts she runs like a top. I have swapped the fuel pump relay to see if that was the problem, still won't start sometimes. Just today it happened again. After trying to get it start for a few minutes I popped the hood to see if I could feel the relay kicking in. All I did was put my fingers on the relay and had someone turn the key and she fired right up, coincidence? I haven't put a fuel pressure gage on it yet but figured that would be my next step.

I'm tired of screwing around with this so I figured I would get the "experts" opinion. What do you all think?


She's a 2000 XLS 4.0 SOHC

Thanks in advance,

Tim

 

[koda2000]

It might have been a coincidence that it started when you touched the relay, but are you sure the relay is making a good connection? You might try removing the relay and inserting a blade-type replacement terminal into each of the socket's recepticals to check for tightness. If you’re not hearing the pump run when it won’t start it sounds like the pump isn’t getting any power or the pump is on the way out. You can put a gauge on the fuel rail to check the pressure, but it sounds like you already know what it’s going to tell you. I would check for power at the pump before replacing it.

 

[JusTheFaxMaam]

I have a 2001 XLT 4.0 SOHC with the exact symptoms, and just regarding the relays... If you want to test them easily, I temporarily swapped the Fuel Pump Relay and PCM Relay with the horn and blower motor relays to see if it helped.

In my case it didn't help at all, and my next step will be accessing the fuel pump itself to verify power when I try to start the vehicle.

Hope this helps

 

[ahuggins6]

get a new pump.

Here's the quick answer... The fuel pump is faulty.

My dad and I left at 4am to drive 3 hours to my grandmother's to work on her van. It had the same characteristics as the OP, but it took a light hammer blow to the bottom of the tank to make the FP make contact internally and run. Carried every tool we had except the kitchen sink. We pulled the pump out of the tank, and it still had to be bumped to run. Once running, it had perfect pressure and performance, but inside the motor there was a problem, because the parts stores did not have the exact replacement assembly, so we just got the motor and that fixed it. To add to your entertainment, the first pump we put in (about 2pm) that day did not work at all.... So we spent 3 hours trouble shooting where our new problem was. After pulling the tank a second time, disassembling the pump a second time, running to town (about 7pm) for a new and putting it all back together, we were able to leave her house at about 10:45 that night and make the 3 hour drive back home.

Get a new pump and test it before you put the tank back in the truck....

 

[bobflood]

+1 on the fuel pump starting to fail as the most likely issue. However, one more thought - make sure that the inertia switch in the pass side kickplate is OK and firmly plugged into it's connector. That switch is a safety thing that is supposed to cut off power to the fuel pump in case of an accident.