1988 F150 5.0 Fuel pump Problems
09-03-2011, 07:14 PM
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1988 F150 5.0 Fuel pump Problems
I am having problems getting fuel delivered to the engine. My truck will start with starting fluid an then die. When I turn the key on you can hear the fuel pump run for a few seconds and then quit. I have disconnected the fuel line from the fuel rail and there is no fuel coming out even though the fuel pump still kicks on and off when I turn the igniton on. Any suggestions would be helpful. Thanks
09-03-2011, 10:54 PM
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The 2 in tank pumps are new and I have diconnected the fuel lines behind the in line pump and still no fuel comes out when I turn on the ignition from either tank. Is there a seperate relay or switch for the in tank pumps? Thanks again
09-04-2011, 12:12 AM
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High pressure fuel pump location
Fuel Pump Control Wiring Circuit
Gauges Wiring Circuit
Fuel Tank Selector Valve
In Tank fuel pump(s) do not operate - 6 port fuel selector valve with hot fuel handling - Diagnostic flow chart
"An in-line reservoir has been included in the fuel system. Under normal operating conditions, valving in the in-line reservoir allows the high-pressure pump and engine to be supplied with fuel directly from the tank while return flow is routed directly back to the tank. When the pick-up is again submerged, normal operation resumes. The dual function reservoir combines the function of the reservoir with the function of a mechanically actuated selector valve.
Fuel selector valve/dual function reservoir. Vehicles with dual tanks have three electric fuel pumps. Two low pressure in-tank fuel pumps located in both the front and rear tanks, pump fuel into a reservoir. A high pressure in-line fuel pump than takes the fuel from the reservoir to the fuel injectors. This system can draw fuel from either the front or rear fuel tank unit. With the ignition in START or RUN, current flows through a fuse link to the fuel pump relay. The dual function reservoir replaces the six port selector valve on fuel injected dual tank vehicles. The dual function reservoir switches the tank from which the engine draws fuel mechanically, instead of electronically.
The dual function reservoir operates as follows: Fuel pressure created by the selected in-tank fuel pump exerts force on a 3 inch fluorosilicon diaphragm which is in turn connected to a T-bar and two shafts. This force moves the valve shaft, simultaneously opening and closing supply on the opposite side of the diaphragm, moving the valve shafts to open the alternate fuel tank ports." -@LLD@T@
As it goes with fuel - Using full
protection, plenty of ventilation with a fan (air dilution in case of an inevitable spark) will make life "easier" and above all, have fun! 
Fuel Pump Control Wiring Circuit
Gauges Wiring Circuit
Fuel Tank Selector Valve
In Tank fuel pump(s) do not operate - 6 port fuel selector valve with hot fuel handling - Diagnostic flow chart
"An in-line reservoir has been included in the fuel system. Under normal operating conditions, valving in the in-line reservoir allows the high-pressure pump and engine to be supplied with fuel directly from the tank while return flow is routed directly back to the tank. When the pick-up is again submerged, normal operation resumes. The dual function reservoir combines the function of the reservoir with the function of a mechanically actuated selector valve.
Fuel selector valve/dual function reservoir. Vehicles with dual tanks have three electric fuel pumps. Two low pressure in-tank fuel pumps located in both the front and rear tanks, pump fuel into a reservoir. A high pressure in-line fuel pump than takes the fuel from the reservoir to the fuel injectors. This system can draw fuel from either the front or rear fuel tank unit. With the ignition in START or RUN, current flows through a fuse link to the fuel pump relay. The dual function reservoir replaces the six port selector valve on fuel injected dual tank vehicles. The dual function reservoir switches the tank from which the engine draws fuel mechanically, instead of electronically.
The dual function reservoir operates as follows: Fuel pressure created by the selected in-tank fuel pump exerts force on a 3 inch fluorosilicon diaphragm which is in turn connected to a T-bar and two shafts. This force moves the valve shaft, simultaneously opening and closing supply on the opposite side of the diaphragm, moving the valve shafts to open the alternate fuel tank ports." -@LLD@T@
As it goes with fuel - Using full
protection, plenty of ventilation with a fan (air dilution in case of an inevitable spark) will make life "easier" and above all, have fun!
Last edited by bluecar5556; 09-04-2011 at 01:21 AM.
09-04-2011, 08:01 AM
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Thanks for the info. Very Helpful. If there is no pressure in line should the fuel pump continue to run when the ignition is turned on? Mine runs a few seconds and shuts off as it should with pressure. And I have the lines disconnected. Does it control the in line pump or the in tank pumps or both? Thanks for the responses.
09-04-2011, 02:47 PM
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Shorting out SPOUT connector pin #6 to STI connector will keep fuel system running, instead of the ignition switch in RUN position only priming the fuel system for 2 seconds, this is normal.
Yes, both the low pressure and high pressure pumps are supposed to have power.
Yes, both the low pressure and high pressure pumps are supposed to have power.
Last edited by bluecar5556; 09-04-2011 at 02:49 PM.
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09-07-2011, 03:26 PM
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I have been taking a break on my truck to regroup. Hoping for some suggestions. Here is where I am at now, I know there is power to the pumps and the relay is good. Is it possible that the reservoir valve is bad and is there a way to check it? Thanks for any info.
04-26-2015, 04:39 PM
#9
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Recurring fuel pump? problems F150 , 302, 1988
Have replaced at least four fuel pumps, relays over the past few years. Have dual tanks. After new fuel pump is installed, will run fine for four, five six months, then will be driving and it will sputter and stop. Next day will start up just fine, but cycle starts up again.
Last year , replaced both pumps in tanks, new relay, fine for a year. Last week drove 10 minutes and it stopped. Next day started right up, but seven minutes later stopped. Started it an hour later and ran perfectly for 2 minutes. Next day, same pattern. Starts perfectly, runs great for 7-8 minutes, then no gas to engine. An hour later, runs great for 2 minutes. Any suggestions?
Last year , replaced both pumps in tanks, new relay, fine for a year. Last week drove 10 minutes and it stopped. Next day started right up, but seven minutes later stopped. Started it an hour later and ran perfectly for 2 minutes. Next day, same pattern. Starts perfectly, runs great for 7-8 minutes, then no gas to engine. An hour later, runs great for 2 minutes. Any suggestions?
04-26-2015, 05:19 PM
#10
Have replaced at least four fuel pumps, relays over the past few years. Have dual tanks. After new fuel pump is installed, will run fine for four, five six months, then will be driving and it will sputter and stop. Next day will start up just fine, but cycle starts up again.
Last year , replaced both pumps in tanks, new relay, fine for a year. Last week drove 10 minutes and it stopped. Next day started right up, but seven minutes later stopped. Started it an hour later and ran perfectly for 2 minutes. Next day, same pattern. Starts perfectly, runs great for 7-8 minutes, then no gas to engine. An hour later, runs great for 2 minutes. Any suggestions?
Last year , replaced both pumps in tanks, new relay, fine for a year. Last week drove 10 minutes and it stopped. Next day started right up, but seven minutes later stopped. Started it an hour later and ran perfectly for 2 minutes. Next day, same pattern. Starts perfectly, runs great for 7-8 minutes, then no gas to engine. An hour later, runs great for 2 minutes. Any suggestions?