1992 F150 Won't Start
11-29-2010, 02:37 PM
#1
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1992 F150 Won't Start
So my 92' F150 won't start. It will crank fine, and every now and then seem like its going to catch but never will. I had this problem about a month ago and I replaced the fuel pump relay which solved the problem for a month or so. A week ago the problem came back.
The fuel system is working fine, I've got 40 psi at the fuel rail. I replaced the relay, so thats not it. Here's the interesting part: when I turn the ignition to the start position the pump turns on and puts some fuel in the system (not sure if its in the injectors or what) then if I take the relay out the engine will fire up and run fine, until what little fuel there is runs out.
Any ideas?
The fuel system is working fine, I've got 40 psi at the fuel rail. I replaced the relay, so thats not it. Here's the interesting part: when I turn the ignition to the start position the pump turns on and puts some fuel in the system (not sure if its in the injectors or what) then if I take the relay out the engine will fire up and run fine, until what little fuel there is runs out.
Any ideas?
11-29-2010, 07:06 PM
#4
April 2010 TOTM Winner
Run the Codes, ah' beat yer to it ymeski56. lol
Yeah, as realtree4x4 and nitehawkjr said;
Replace Fuel filter
& which Engine do you have?
Have you been driving the truck or has it been sitting for months?
If been sitting for several months; pour 5 gallons of fresh gasoline into one of the tanks and ensure the battery is a strong 12 Volts and try that, because 87-89 octane gasoline becomes STALE after only 6-weeks, yeah I know we all have driven vehicles with gas older than 6-weeks...
You know; the problem may not be fuel related. just sayn...
Have you tried spraying Starting Fluid into the Air Intake while someone spun the engine over?
IT ALSO COULD BE the:
ICM (Ignition Control Module) (aka: TFI)
PIP
Coil
Or
It could be something as simple as the Air Filter is partially plugged.
How long has it been since the engine has had a tune-up?
All I got!
Yeah, as realtree4x4 and nitehawkjr said;
Replace Fuel filter
& which Engine do you have?
Have you been driving the truck or has it been sitting for months?
If been sitting for several months; pour 5 gallons of fresh gasoline into one of the tanks and ensure the battery is a strong 12 Volts and try that, because 87-89 octane gasoline becomes STALE after only 6-weeks, yeah I know we all have driven vehicles with gas older than 6-weeks...
You know; the problem may not be fuel related. just sayn...
Have you tried spraying Starting Fluid into the Air Intake while someone spun the engine over?
IT ALSO COULD BE the:
ICM (Ignition Control Module) (aka: TFI)
PIP
Coil
Or
It could be something as simple as the Air Filter is partially plugged.
How long has it been since the engine has had a tune-up?
All I got!
Last edited by 1987 F-150 XLT 4x4; 11-29-2010 at 07:09 PM.
11-29-2010, 11:28 PM
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Its a 5.8L V8. If I prime the engine by turning the key to the start position once or twice and then take the fuel pump relay the engine starts up just fine, which makes me think its not a problem with the spark.
Also, the truck had only been sitting overnight.
Also, the truck had only been sitting overnight.
11-30-2010, 11:02 AM
#6
Senior Member
The pumps are controlled by the PCM when the engine is running. This is how my manual explains it.
When the ignition switch is on, it turns on the EEC power relay on. The EEC power relay supplies power to the power train control module (PCM) and the control side of the fuel pump relay. Power for the fuel pump(s) is supplied through a fuse link or high current fuse attached to the starter solenoid (battery side). From the fuse link or high current fuse power flows through the fuel pump relay, inertia switch, selector switch to the fuel pump(s). The fuel pump relay is controlled by the PCM.
When the ignition switch is turned on the fuel pump(s) will operate. If the ignition switch is not turned to the start position the PCM will shut the fuel pump(s) off after 1 second. The PCM will operate the pump(s) when the ignition switch is turned to the start position to provide fuel while cranking.
After the engine starts, the PCM willcontinue to operate the pump(s) until the engine stops, drops below 120rpm, or the inertia is tripped.
When the ignition switch is turned on the fuel pump(s) will operate. If the ignition switch is not turned to the start position the PCM will shut the fuel pump(s) off after 1 second. The PCM will operate the pump(s) when the ignition switch is turned to the start position to provide fuel while cranking.
After the engine starts, the PCM willcontinue to operate the pump(s) until the engine stops, drops below 120rpm, or the inertia is tripped.
Did you replace the EEC relay also or just the pump relay? If you did both I would check out the wiring coming from the PCM to the relay and. Also check out the grounds for them. If not I would replace it also. The pump pressure you have is ok as it should run 35-45 psi. Also it could be that the PCM is not sending a signal to the injectors to pulse.
Last edited by Nitehawkjr; 11-30-2010 at 12:42 PM.
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12-02-2010, 05:49 AM
#8
April 2010 TOTM Winner
[quote=Nitehawkjr;666534]The pumps are controlled by the PCM when the engine is running. This is how my manual explains it.
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That's a good post nitehawkjr
When the ignition switch is on, it turns on the EEC power relay on. The EEC power relay supplies power to the power train control module (PCM) and the control side of the fuel pump relay. Power for the fuel pump(s) is supplied through a fuse link or high current fuse attached to the starter solenoid (battery side). From the fuse link or high current fuse power flows through the fuel pump relay, inertia switch, selector switch to the fuel pump(s). The fuel pump relay is controlled by the PCM.
When the ignition switch is turned on the fuel pump(s) will operate. If the ignition switch is not turned to the start position the PCM will shut the fuel pump(s) off after 1 second. The PCM will operate the pump(s) when the ignition switch is turned to the start position to provide fuel while cranking.
After the engine starts, the PCM willcontinue to operate the pump(s) until the engine stops, drops below 120rpm, or the inertia is tripped.
When the ignition switch is turned on the fuel pump(s) will operate. If the ignition switch is not turned to the start position the PCM will shut the fuel pump(s) off after 1 second. The PCM will operate the pump(s) when the ignition switch is turned to the start position to provide fuel while cranking.
After the engine starts, the PCM willcontinue to operate the pump(s) until the engine stops, drops below 120rpm, or the inertia is tripped.
Did you replace the EEC relay also or just the pump relay? If you did both I would check out the wiring coming from the PCM to the relay and. Also check out the grounds for them. If not I would replace it also. The pump pressure you have is ok as it should run 35-45 psi. Also it could be that the PCM is not sending a signal to the injectors to pulse.
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That's a good post nitehawkjr
