fuel pumps
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New User
Joined: Jan 2005
Posts: 3
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fuel pumps
lost front and rear pump ran by pass test niether ran no power to either tank? eec relay? or fuel pump relay?we ran in to a lot of water on trip to ny had to replace coil and plug on side could this have effected eec module truck would dry out run fine get wet skip did this for about 400 miles
Post Fiend
Joined: Mar 2003
Posts: 14,413
Likes: 3
From: Sarnia, Ontario, CANADA!
If you have someone turn the key forward (but don't start it) you should hear the relay click (in the hood area). If you don't hear it then start there (replace it?). Good luck!
-Matt
P.S. Welcome to FTE!
-Matt
P.S. Welcome to FTE!
Elder User
Joined: Sep 2004
Posts: 941
Likes: 4
Get a test light or voltmeter. Turn the key to on. Probe the "FP" wire on the 6 pin self test connector (should be the same connector pin you are using to attempt a bypass).
If you have voltage at this point, the EEC power relay and FP relay coil are good. If you don't, the most likely suspect is the EEC power relay. You could isolate the EEC relay by attempting a KOEO test. If the test runs and you get any codes at all (pass or fail) the EEC relay is good. This would leave just the coil in the FP relay as having failed open.
Assuming there is power to the FP line, then grounding it should send current through the relay coil in the FP relay. This should close the contacts and send power from the battery to the inertia switch, from there to the tank selector switch, and from there to the selected fuel pump.
Another diagnostic tool is simply grounding the FP line. If you hear a "click" as you make this connection, it is the FP relay pulling in, and the EEC power relay and FP relay coil are good. If the pump doesn't run, the power is being interrupted by one of:
1) The fusible link connecting the battery to the FP relay
2) The inertia switch
3) The tank selector switch.
You HAVE checked and reset the inertia switch, right?
If you have voltage at this point, the EEC power relay and FP relay coil are good. If you don't, the most likely suspect is the EEC power relay. You could isolate the EEC relay by attempting a KOEO test. If the test runs and you get any codes at all (pass or fail) the EEC relay is good. This would leave just the coil in the FP relay as having failed open.
Assuming there is power to the FP line, then grounding it should send current through the relay coil in the FP relay. This should close the contacts and send power from the battery to the inertia switch, from there to the tank selector switch, and from there to the selected fuel pump.
Another diagnostic tool is simply grounding the FP line. If you hear a "click" as you make this connection, it is the FP relay pulling in, and the EEC power relay and FP relay coil are good. If the pump doesn't run, the power is being interrupted by one of:
1) The fusible link connecting the battery to the FP relay
2) The inertia switch
3) The tank selector switch.
You HAVE checked and reset the inertia switch, right?
