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Hey guys,
My 93 F150 300 six 5 speed died the other day. It cranked and started as normal, then as it was idling died and did not restart.
It will crank, but not fire.
Fuel pumps will not turn on
Here is what I have checked so far:
I jumped the fuel pump relay from pin 87 to 30 and the selected fuel pump will turn on but won't start.
I grounded pin 6 at the EEC and the selected fuel pump will turn on, but won't start.
I ohmed pin 22 at the PCM to fuel pump relay terminal 85, 0.9 OHM
Relay terminal 86 is hot with key on
Relay terminal 30 is hot all the time
At the PCM:
pin 1 always hot
pins 37 and 57 hot with key on
pin 20 good ground all the time.
The other thing I noticed is that the Check engine light no longer illuminates with key on.
Is there anything else I need to check before replacing the PCM?
Thank Y'all in advance for any and all help.
Similar thing happened to me not too long ago. Started my truck, it was running fine, then all of the sudden it just died. It would crank but it wouldn't fire. There was no noise from the fuel pump when I turned the key after it happened. I, however, also smelled a distinct burnt electronic smell which stunk up the whole cab when this happened to me. Turns out the PCM was fried. When I pulled it out there was corrosion and water inside the plug. I purchased my replacement PCM from O'reilly auto.
Just to clarify, when the truck is turned to on the pumps do not run for 1 second?
Correct, pumps do not run when turning on key.
The only way I can get either pump to come on is by bypassing the the fuel pump relay or by grounding out pin 6 at the diagnostic plug.
It could possibly be a bad EEC. I think that will cause a no CEL/no prime situation.
For the PCM- test for spark at the plugs with the computer hooked and unhooked. If you don't have spark with it connected, then have it with it not connected, the PCM is most likely bad.
Last edited by Thinlizzy13; Sep 9, 2017 at 11:29 AM.
Reason: Typos
I might be using the wrong terminology here. I am concerned with which ever controller is on the drivers side firewall. This is where I'm loosing the ground signal to enable the fuel pump relay.
I will also report back after checking spark.
I work on heavy equipment by trade, and am used to an electronic controller supplying ground for a relay. So with my instinct, when I wasn't getting the controller supplied ground, I checked the wire. When the wire checked good, I assume the driver in the either shut off due to other programmed logic or a faulty driver.
So no spark either, I pulled the engine controller and took the cover off. No real smell of anything burnt, but did see a burnt spot on the board. So I rolled the dice and ordered and installed a reman Cardone. I turned on the key and the fuel pump engaged and she fired right up.
So no spark either, I pulled the engine controller and took the cover off. No real smell of anything burnt, but did see a burnt spot on the board. So I rolled the dice and ordered and installed a reman Cardone. I turned on the key and the fuel pump engaged and she fired right up.
Yeap, both the Black and the Green Capacitors had failed. Both appear to have been leaking for a lengthy period of time.
Glad to know the reman PCM has worked out for you!
Thanks, it very well could have been leaking a long time. My dad bought the pickup new in 93 and I know it's never been changed. I haven't had a chance to drive it yet but it sure started strong and idled really smooth.
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