Need Help Trouble shooting engine
#16
10-21-2017, 12:09 PM
Blue grass7 I went out and turned the key on and left it for about 3 minutes. I got no flashing Light or even a Theift Light. Only the normal lights when turning the key on. I will hook the fuel test gauge up to the fuel rail and cycle the key on and off to see if I get any reading at all. I still need to check the fuse and take a reading at the inertia valve. To cold right now to do much of anything. Thanks for your help and info, it is appreciated.
Mel
Mel
Last edited by mhbell; 10-21-2017 at 12:11 PM. Reason: spelling
#17
10-21-2017, 03:10 PM
UPDATE
UPDATE It warmed up again when the sun came out so I went out to my F150 and did the following. I turned on the Ignition switch and observed the following. The theft light came on for a couple of seconds and went out. No flashing or steady theft light. I then hooked my fuel pressure test gauge to the fuel rail and proceeded to turn the key on and off at least 10 times. The gauge read zero. I unhooked the gauge and a few drops of gas dripped out of the hose. I now feel for sure it is a fuel pump problem and not a PATS problem. It could be a Fuel filter, fuse or inertia switch problem. I will change the filter. Check the fuse. and check voltage at the inertia switch. Anything else I should do at this point?
Mel
Checked the fuses this afternoon, and they are all OK.
UPDATE It warmed up again when the sun came out so I went out to my F150 and did the following. I turned on the Ignition switch and observed the following. The theft light came on for a couple of seconds and went out. No flashing or steady theft light. I then hooked my fuel pressure test gauge to the fuel rail and proceeded to turn the key on and off at least 10 times. The gauge read zero. I unhooked the gauge and a few drops of gas dripped out of the hose. I now feel for sure it is a fuel pump problem and not a PATS problem. It could be a Fuel filter, fuse or inertia switch problem. I will change the filter. Check the fuse. and check voltage at the inertia switch. Anything else I should do at this point?
Mel
Checked the fuses this afternoon, and they are all OK.
Last edited by mhbell; 10-21-2017 at 05:50 PM. Reason: added checked fuses
#18
10-21-2017, 09:21 PM
Ok now you eliminated the PATS system.
Here is the rest of the story.
The fuel pump is operated by a slave relay and not directly from the PCM.
How it works;
The PCM grounds the relay through a short time timer to operate it when you turn the key to run and after the engine cranks the short time timer keep the ground on the relay Should the engine stop, the timer no longer gets the signal to keep the pump running hence the fire protection along with the crash sensor function is always in play.
The relay connects 'separate' fused power to the pump through the crash sensor..
Be sure this is all working.
There could be a harness, ground or a connector issue back at the tank.
Better to be sure of all this before going to the hassle of changing the pump.
Now your an expert on the pump operation.
Good luck.
Here is the rest of the story.
The fuel pump is operated by a slave relay and not directly from the PCM.
How it works;
The PCM grounds the relay through a short time timer to operate it when you turn the key to run and after the engine cranks the short time timer keep the ground on the relay Should the engine stop, the timer no longer gets the signal to keep the pump running hence the fire protection along with the crash sensor function is always in play.
The relay connects 'separate' fused power to the pump through the crash sensor..
Be sure this is all working.
There could be a harness, ground or a connector issue back at the tank.
Better to be sure of all this before going to the hassle of changing the pump.
Now your an expert on the pump operation.
Good luck.
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Davids460
1987 - 1996 F150 & Larger F-Series Trucks
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