EEC not booting

[tubicinator]

'95 XLT 4.0. Problem - The engine cranks, but doesn't always start. I have determined that the EEC doesn't always boot with KOEO because I don't here the "whir" of it booting. When I do here the "whir" the engine starts normally. Has anyone else encountered this? I speculate it's a problem with either the ignition switch or the EEC itself.

 

[Doug]

I doubt it's an ECM problem, that whirring you hear when you turn on your truck is the fuel pump priming. If you're not hearing the whirr I'd start with the fuel pump. You can start with checking the fuel pump cut off switch underneath the dashboard on the passengers side down by your feet. On the chance it actually is a ECM problem try running the codes with a code scanner and see what it comes up with. If it doesn't connect there is a possibilty there is a problem with the ECM but there is a good chance you have a bad fuel pump.

 

[Glacier991]

Often a fuel pump relay is the culprit. It's a cheap an easy fix when THAT is the problem. Your computer is solid state, there's no noise. DOUG is absolutely correct. A fuel pressure gauge is about $30 and would give you a pretty fast indication of whether your pump is firing up when you turn the ignition switch on (It should fire up briefly until you achieve proper fuel rail pressure of 30-35 PSI). The fuel pump is in the fuel tank, listen closely when you switch the ignition on after a long period in which the fuel pressure would have bled off, and the whir you hear SHOULD be coming from that area.

I hesitate to simply implicate the fuel pump because there IS a relay involved (and an inertial switch which rarely goes bad)... the fuel pump is about $75-90 and the relay is about $15. Fuel pump is in the fuel tank and when you replce it you need to also replace the strainer ($15). It is not a fun job. I have replaced two fuel pumps in the last 2 years. In one case it WAS the pump that failed and in another I discovered AFTER diagnosing the pump and replacing it (Did I mention this is NOT a fun job) that is was a relay in a special relay assortment ($150 for THIS relay)...

I hate to see anyone just throw parts at a problem and hope... but on this one... the relay is pretty cheap.

 

[tubicinator]

Not EEC

Thanks for putting me on the right track. I always thought that the KO "Whirr" was the EEC booting and the fuel pump priming. When I heard neither I thought perhaps the EEC not booting was preventing the fuel pump from getting powered up as well. All I knew for sure was I had spark and air but no fuel.

The car has started every time again - the frustrations of an intermittent problem. Probably a function of our wildly fluctuating temperatures in Nashville this week. Nevetheless I did replace the relay.

Next, I'll get after repairing the broken air mix plenum actuator. I found directions for a free fix on the net as well. Does anyone know if Ford ever stepped up to provide some relief for this blatant materials flaw out of warrantee?

Cool forum. I imagine I'll be seeking your help again in the future since I plan on keeping this '95 at least 2 more years.

 

[tubicinator]

Well, even with the new fuel pump relay the problem continues. We had a good 20 clean starts then this morning the fuel pump didn't prime again. It worked once this afternoon, though, and failed again on 4 more tries. I jigggled relays and the wire to the inertia switch. I guess I need to test electricals all the way back to the pump but my new question is:
Would a failing fuel pump work intermittently? Where is the sending unit? What else might it be? I'd like to try everything I can within reason before I pay someone else to replace the pump.

 

[ExplorerDMB]

sending units in the tank with the pump