1991 F150 Lariat
08-24-2009, 07:57 PM
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1991 F150 Lariat
I have a F150 Lariat 5.0 that is hard to start, the motor turns over just fine, I recently replaced the ECM and Fuel relay, I have dual tanks and the fuel pressure is 31 to 33 lbs for each fuel pump. The truck has 159,850 miles on it. It has the original fuel pumps. Is their an electronic relay or valve that controls the fuel that is being pumped from either the front or rear tank? Their are times that the truck will just shut off in traffic, you coast off the road then you re-start the engine.
08-24-2009, 08:09 PM
#2
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Hi Bill, sounds like you are aquainted with these trucks. When doing the fuel pressure test, how long did the pressure hold after shut down? Am not liking the engine shut down while driving, am thinking another possible problem for that. For initial start up suggest cycling the ignition key off to on several times before engaging starter. Just to make sure we have pressure on the rail.
08-24-2009, 08:17 PM
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I was told that I probably needed to change the ignition coil and ignition stator, I purchased from Ford and changed both of these items recently. I can turn on the key and hear the fuel pump cycle for about three seconds, the truck cranks fine but if I turn on the switch I sometime hear the pump just keep cycling until I turn of the switch. When this happens the engine will not start.
08-24-2009, 08:26 PM
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Fuel pumps have two sources of power and both from the ECU. One is momentary on, thats the 2-3 second on time. After the engine is fired up and oil pressure is registered then the ECU will provide continuous power to run the pumps. Not liking the non cycling of the pump during the key on cycle.
08-24-2009, 08:34 PM
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This problem is the same on the front or rear pump, I don't think it is a fule pump problem. I was told yesterday that an electronic valve or solenoid controls the fuel pumps when you are switching between either front or rear pumps.
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08-25-2009, 08:27 AM
#9
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Your 91 could have a electric fuel valve, issues usually resulted in the tanks not switching or the fuel return going to wrong tank. On the later models the switch would run the desired pump and thus feed that way.
08-28-2011, 04:19 PM
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I was told that I probably needed to change the ignition coil and ignition stator, I purchased from Ford and changed both of these items recently. I can turn on the key and hear the fuel pump cycle for about three seconds, the truck cranks fine but if I turn on the switch I sometime hear the pump just keep cycling until I turn of the switch. When this happens the engine will not start.
Last edited by willwhipperwill; 08-28-2011 at 04:23 PM. Reason: I have the same problem