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no power to fuel pump relay
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jim schouten
Novice
Jul 3, 2010, 8:12 AM
Post #1 of 17
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no power to fuel pump relay
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i have a 91 safari 4.3 no power to fuel pump relay i think orange wire shoul be hot. fuse for ecm batt is ok but it did blow several times but is ok now if you power up gray wire at relay pump runs i think maybe ecm is bad but im not sure help!!!
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Tom Greenleaf
Ultimate Carjunky
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Jul 3, 2010, 8:25 AM
Post #2 of 17
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Re: no power to fuel pump relay
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Just a maybe for now: Some will give a grace period and or pressure up or cut out fuel pump based on oil pressure. Check for same color wires to oil pressure sender that all is well there to start with. May not do the fail-safe that way,
T
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Hammer Time
Ultimate Carjunky
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Jul 3, 2010, 8:29 AM
Post #3 of 17
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Re: no power to fuel pump relay
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Check the ECM1 and ECMB fuses. You should also have power at the orange wire of the oil pressure switch which will power the fuel pump after cranking even without a fuel pump relay.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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jim schouten
Novice
Jul 3, 2010, 8:54 AM
Post #4 of 17
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Re: no power to fuel pump relay
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ok now i have power to orange wire at oil press switch & at relay this would mean relay bed correct??? mabye i didnt have ing on first time sorry
(This post was edited by jim schouten on Jul 3, 2010, 8:55 AM)
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Tom Greenleaf
Ultimate Carjunky
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Jul 3, 2010, 9:01 AM
Post #5 of 17
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Re: no power to fuel pump relay
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Hammer is right on with this. Plug everything in and test out all fuses with a test light for one that only lights one side. I just knew some of these the fuel pump could be disabled by oil pressure and info sent on for the safety of shutting it down in accident for example,
T
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Hammer Time
Ultimate Carjunky
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Jul 3, 2010, 9:09 AM
Post #6 of 17
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Re: no power to fuel pump relay
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No, the circuit is not designed to disable the fuel pump. It's designed to supply a redundant power supply to the pump for some purpose I can't see.
If you have power to the oil pressure switch, then the truck should run after cranking long enough to build oil pressure, regardless of the condition of the relay.
If you have a testlight that reads either power or ground, check all the sockets at the relay. You should have 2 reading power and 2 reading ground with the engine cranking.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Jul 3, 2010, 9:10 AM)
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Tom Greenleaf
Ultimate Carjunky
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Jul 3, 2010, 9:16 AM
Post #7 of 17
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Re: no power to fuel pump relay
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OK - I stand corrected on the purpose but did think it was involved in some. I know it was on some real old stuff - no oil pressure you got no electric fuel pump. Chevy Vega was the car. Is there one left? LMAO,
T
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Hammer Time
Ultimate Carjunky
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Jul 3, 2010, 9:20 AM
Post #8 of 17
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Re: no power to fuel pump relay
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Did the Vega have an electric fuel pump?
I don't know what the purpose is for this circuit but it won't cut off the pump. It's just a duplicate supply and it will run with either one disconnected.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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jim schouten
Novice
Jul 3, 2010, 10:57 AM
Post #9 of 17
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Re: no power to fuel pump relay
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put on new relay now pump runs after oil pressure comes up but i dont get the 2-3 second prime when you first turn on key . and truck still wont start but it will run on starting fluid??
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jim schouten
Novice
Jul 3, 2010, 11:16 AM
Post #10 of 17
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Re: no power to fuel pump relay
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tom, i put on new relay i grt pump to run after oil press comes up but still wont start. i just ran hot wire direct to puymp runs like crazy but still no start it will run on start fluid maybe not enough fuel pressure?? i have no guage bto check this
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Tom Greenleaf
Ultimate Carjunky
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Jul 3, 2010, 11:17 AM
Post #11 of 17
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Re: no power to fuel pump relay
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HT - That was so damn long ago I think Nixon was still President! I recall no mechanical fuel pump on the Vega. Bet it was a '71 or '72 with carb! Had a pump in the tank I think but might have been in line. I just knew (went to the dead car to fix it) it was lacking fuel and was chasing the line to no where and who knows why I thought of the oil sender as the culprit. It was and when by-passed on location could then move the car to fix it.
But why bother - those had all aluminum engines and blew not smoke but raw oil out the tailpipe by 40k if they didn't rust up to the roof first!
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Now back to the truck with no power for the fuel pump and why. You'll know more about where to check and I'll stay out of this one. I do doubt that it's the fuel pump itself so far on that with no power showing where it should,
Tom
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Hammer Time
Ultimate Carjunky
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Jul 3, 2010, 11:41 AM
Post #12 of 17
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Re: no power to fuel pump relay
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Do you have injector power and pulse?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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jim schouten
Novice
Jul 3, 2010, 12:04 PM
Post #13 of 17
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Re: no power to fuel pump relay
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i have power to 1 side of each injector with key on nothing on other side no change when cranking ov er
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Hammer Time
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Jul 3, 2010, 12:10 PM
Post #14 of 17
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Re: no power to fuel pump relay
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What were you using to test that? You need a special bulb called a noid light. If you use an incandescent test light, you can fry the ECM.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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jim schouten
Novice
Jul 3, 2010, 12:13 PM
Post #15 of 17
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Re: no power to fuel pump relay
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yes i did use regular test light
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Hammer Time
Ultimate Carjunky
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Jul 3, 2010, 12:18 PM
Post #16 of 17
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Re: no power to fuel pump relay
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Get a noid light or a diode light that reads ground.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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jim schouten
Novice
Jul 3, 2010, 12:23 PM
Post #17 of 17
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Re: no power to fuel pump relay
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going to get one thank you for your help ill get back with results
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