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My wife has a 1995 Lincoln 4.6 L with 83K miles which does not start in the morning, but at approximately 1 pm it will start and run perfectly and restart numerous times that afternoon. (outside barometric pressure really builds and the problem did not become evident until the weather cooled off after a record breaking heat wave/drought this summer). It seemed fuel starved since it did not flood at all during trying to start. We believe the problem is with the fuel system. I have already replaced the the fuel filter, but this did not correct the problem. Decided to get a fuel pressure test gauge and checked the pressure at the schrader valve on the fuel rail. Had the wife turn key to the on position, and no pressure was indicated on the gauge. I do not hear the fuel pump, but I never could. My thought is it probably is the fuel pump, but before I drop the tank I would like to know if there is any other possibility which I am not considering.
Location: East of Seattle since 1992, 615' Elevation, Zone 8b - originally from SF Bay Area
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Most fuel pumps can be heard, so it's likely not running. Before dropping the tank, there is a chance that the fuel pump relay is bad, that's a $10 part as opposed to probably several hundred for the pump. Both the relay and the pump itself can have intermittent problems but then eventually die completely. Also check the fuel shutoff, probably in the trunk, maybe turn off and back on to make sure it's all the way on. Someone may have bumped it.
I have trace power from the battery through the relay and out of the inertia switch in the trunk . only things I see left are the the pump driver module and the pump itself. Does anybody know the exact location of the the pump driver module? It is the next thing in the circuit.
Pump driver module is most likely in the trunk, left side behind some carpet.
Question: When you turn the key on, does the check engine light come on? If it does not, the fuel pump will not run. I had a similar problem with an intermittent no start, EEC power relay (for the PCM) was not always turning on. When it failed, there was no fuel pump operation, and the PCM didn't 'wake up'.
What is the temperature in the morning when you try to start the car? I had a problem with a '90 Dodge Ram similar to this. No start in cold morning conditions, but it would fire right up when the sun came out and everything warmed up. Turns out, it was the computer freezing, so apparently there was some condesation built up. So check the PCU, ECM, wherever it may be located. Have you done a diagnostic test using the OBD?
OK I found the the fuel pump driver module, and power is coming to it on the white wire. The fuel pump driver module also is wired to the powertrain control module, but I am uncertain as to what effect that would have on the circuit. finally when I applied 12v to the wires to the pump I heard the pump run but no pressure is indicated on the gauge which I placed on the fuel rail. I just hooked the fuel pump driver module back into the circuit and I am starting to get pressure when I attempt to start the car. Any thoughts or suggestions?
We took the car to a mechanic and he replaced the fuel-pump control module and it now starts. Part $112.00 Labor $35.00 x 1.5 for a total of $165.08.
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