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Discussion Starter #1
94 4.0 Auto is having an intermittent quitting problem when it warms up. After it quits, it will start and run for a few seconds then die again. If I let it sit for 15-30 minutes it will run like there was no problem at all.

-Replaced/cleaned shifty looking battery terminals.
-Pulled codes and got 157 & 158 both MAF related. Replaced with good MAF.
-Idle Fuel Pressure is 40psi but I have not tested when it happens.

I am suspecting a possible bad fuel pump or regulator, sound right? Input?
 

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seems like idle pressure is kinda high. under load should be 39-40 psi.

you could also have a bad TFI. do you still have spark when it dies?
 

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Discussion Starter #3
It has happened on 3 occasions and everytime, I did not have the equipment to check it, so I don't know. I am now driving around with the fuel pressure tester and spark tester.
 

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TFI module - when it gets hot it will stop sending the ecm the correct injection timing, but when you start it it returns to closed loop for a few seconds, then die - sometimes there will be spark, and others it wont.

you can take it to napa and have it tested, and "most" of the time if its bad, it will fail. you will need a 5 mm socket


possible fuel pump and/or the ECM relays getting heat soak
 

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i think its a 5.5mm socket...
 

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Just throwing this out there to make sure you guys are on the right track here:D You do know that the 4.0L explorer dosen't have a dizzy right? It's a EDIS style system and the EDIS module is behind the battery mounted to the radiator support. It could be bad and in 20 years I've seen a few, most were damaged by battery acid. The module is held to the radiator support by 5.5mm head screws.
 

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Just throwing this out there to make sure you guys are on the right track here:D You do know that the 4.0L explorer dosen't have a dizzy right? It's a EDIS style system and the EDIS module is behind the battery mounted to the radiator support. It could be bad and in 20 years I've seen a few, most were damaged by battery acid. The module is held to the radiator support by 5.5mm head screws.
eh, its been a long month already.:flipoff2: but i was correct.:D
 

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Discussion Starter #9
I forgot all about the Ford modules.. Its been 6 years since I changed one on a 5.0.. I hope thats the problem because I am going to swap it out today.
 

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I'm still guessing fuel pump. I'd try to get it to die with a guage installed before you throw anymore parts at it at least that way you can narrow it down to fuel or spark.
 

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Discussion Starter #12
I pulled the module to have tested at vatozone and I HAVE been driving around with the fuel pressure tester attached:laughing:
 

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Discussion Starter #13 (Edited)
The thing quit today and I had the fuel tester on:grinpimp:

It was idling and had 10 PSI fuel pressure!

It sputtered and died again. So I relieved the pressure via the tester and I got more air than fuel out of the line. After several 'purgings' of the air, I started to get fuel and the pressure went back up to 40 at idle.

Would that be considered a fuel pump problem?
 

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fuel pump, or your running it out of fuel :flipoff2:.
 

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no TFI ? doooooh :homer:

i was thinking early 2.9 - not 4.0 sorry -

check the relay - heat soak can make them loose amps and drop pressure - then cool and work - i know its a pain to have tools when it dies, but check the output voltage of the relay, and if you can the impact sensor ( ive seen them melt when hot ) or at least if you replace the fuel pump, install a new relay
 

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40 is too high at idle. It should be about 30 at idle and then 40 with the fuel pressure regulator vacuum line removed. Sounds like you may have a vacuum problem to the fuel pressure regulator and a pump that is starting to go out.
 

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Discussion Starter #17 (Edited)
I suspect the heat of the relay to be a problem, its hot to the touch. I removed the fuse panel cover and it lasted a whole lot longer before happening.
 

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i ran my f350 tow rig out of gas and it did the same thing turns out it just cloged the fuel filter so sometimes it would lean out and die but if i let the filter settle fuel would flow again
 
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