No power to fuel pump
#1
#2
Use a test light, or a voltmeter and see if voltage is getting to the injectors. If there is no voltage going to the injectors I would say the computer is toast.
I had a 87 F150 with a 4.9 EFI. The computer was fried, the computer wasn't grounding out the injector relays or fuel pump relay, so power wasn't getting to the fuel pump or the injectors.
I had a 87 F150 with a 4.9 EFI. The computer was fried, the computer wasn't grounding out the injector relays or fuel pump relay, so power wasn't getting to the fuel pump or the injectors.
#4
Use a test light, or a voltmeter and see if voltage is getting to the injectors. If there is no voltage going to the injectors I would say the computer is toast.
I had a 87 F150 with a 4.9 EFI. The computer was fried, the computer wasn't grounding out the injector relays or fuel pump relay, so power wasn't getting to the fuel pump or the injectors.
I had a 87 F150 with a 4.9 EFI. The computer was fried, the computer wasn't grounding out the injector relays or fuel pump relay, so power wasn't getting to the fuel pump or the injectors.
#5
You have the PCM power relay but the computer has nothing to do with picking (grounding) that relay or sending power to the injectors.
The PCM power relay coil has one side permanently hooked to ground and the other side is powered by the Ignition switch.
The PCM power relay does send power to all of the injectors, fuel pump relay coil and other solenoids.
You can unhook the computer and take it out of the truck and turn on the key and still have power to all of the injectors and the fuel pump relay.
The 1992 is the same as the 1993 wiring below.
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#6
It could be a bad computer.
Yes you can bypass the Ignition switch for a test. Do you have open (bad) fuses?
#7
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#9
Hmm...this computer thing would make sense...my truck also gives the fuel pump circuit open, EEC processor to motor ground...never knew if that ground was the EEC itself or not. My truck has a surging idle, but always runs fine...
And Rangergirl, sorry to hijack. Seems to me that however you jumped it before, it bypassed the EEC (possibly because it's fried) and made all the injectors fire at the same time, instead of in sequence...causing it to ultimately dump fuel out the exhaust, when it had nowhere else to go. If my theory is correct and it would have kept running, it would have hydro-locked the engine. Good luck, I'll be keeping an eye on this to see what fixes it...
And Rangergirl, sorry to hijack. Seems to me that however you jumped it before, it bypassed the EEC (possibly because it's fried) and made all the injectors fire at the same time, instead of in sequence...causing it to ultimately dump fuel out the exhaust, when it had nowhere else to go. If my theory is correct and it would have kept running, it would have hydro-locked the engine. Good luck, I'll be keeping an eye on this to see what fixes it...
#14
I think your computer is not telling the injectors when to open or close. so they are probably, open. And you hot wiring the fuel pump, the fuel pump is constantly running. This will fill the combustion chamber with fuel and the fuel will pour out the exhaust and get into the oil.
I believe you need another EEC.
I believe you need another EEC.