No fuel getting to the motor form the fuel pump

Asked by Apr 06, 2017 at 06:46 AM about the 1996 Chevrolet Tahoe LT 2-Door 4WD

Question type: Maintenance & Repair

Week my brother was driving along one day last
week when his truck just stopped died in its tracks
so we towed it to his house and realised that he
had no fuel pressure  to the motor so we crawled
under his truck to look at the wire's cause he had
just replaced the fuel pump and we noticed that
the main positive wire had been striped as if
someone else had went down there and tested the
wire's before  so we went ahead and tested them t
self and we only had power to the fuel gauge from
the tank to the cab so we followed the positive
wire from under the hood to see if we had any
power under the cab and we had power all the way
to the connector for the fuel pump form the fuse
box but NO power was getting to the fuel pump
itself. so we ran a new positive wire from the wire
coming out of the fuse box to down under the cab
cause we knew that it had power and we ran it all
the way to the fuel pump and then we cut all 3 of
the factory wire's and wired them directly up to the
fuel pump and got fuel pressure so we started the
truck and let it run for like 5 to 10 minutes while we
went in side and then his truck just shut off and we
don't know y. So can someone plz help us figure
this out please

14 Answers


check your work , once it shut down was there still power to the pump ? connections must be clean and tight , the pump needs a good ground also .


Yes, double check your work, and make sure there is a good ground as beatupchevy is saying. Also there may be a problem with the fuel pump relay. May want to change that out.

We already changed the relays and cleaned the grounds for the fuel tank


So is does the fuel pump run? Is there a power issue?


I think that your asking for big trouble dude. What wire did you use from the fuse box ? was it the same fuse that's for the fuel pump? If not then the ECU no longer controls the pump. The fuel pump should run for a few seconds when you turn the key to "run" ,, then you should hear it stop after a few seconds ,, does yours stop? If it doesn't stop then you have bypassed the fuel pressure sw and the pumps running "balls to the wall" to the regulator. Sorry if I read your post wrong but the pressure switch controls the fuel pump cycle ... the fuel pump fuse is isolated from the 12VDC through an internal circuit and is not always hot. BEWARE


If the pump runs without pressure control you may have sent too much pressure to the regulator at the fuel rail and flooded the system


That is not possible Tom, fuel would not get past the fuel injectors. They would have to be wide open, leaking. Fuel pressure from the pump has nothing to do with this. The new pump is not running


True the fuel can't get past the injectors He said the car was running ,,no ... then he said the car stopped.. answer this Rowe ... when the car stopped did the fuel pump continue running or are you assuming the car quit because the fuel pump stopped? Problem is that you can't be certain that's what caused the car to stop so if the pump continued to run the you are either (or hopefully) blow a fuse or if the fuse has been "upgraded" you will Lock rotor and wipe the matrix wiring out in the fuse box ,,, have you ever had to check the Buss interconnects on a fuse box? In my whole life I have never gave advice or condoned someone "bypassing" wiring on a fuel pump. Have you ever seen a ruptured fuel line hit an exhaust manifold? I'm a design electrical engineer and when I give advice .. you can be sure I won't assume anything ,,we're talking about a 21 year old car that already has a suspected wiring issue .. next this guy said .. if I read it correctly ,, there were wires that went into the pump but he wired directly into the pump ... if you have voltage but no power then the pressure sw may be bad ,, now if you wire directly to the FP motor then you have bypassed the pressure sw.., if you study the algorithm of an ECU controlling a fuel pump you will soon see that it's not the same as a well pump pressure switch. Re-read what this dude did and if your happy with it than


Read what correctly? Last question I asked was "So is does the fuel pump run? Is there a power issue" So I mean I'm glad your so attentive, your right, I don't know what caused the truck to stop running, thus the question? And there is only a fuel regulator that runs off of vacuum, no electric pressure switch. This has a spider injection assembly. So what fuel switch are you talking about? There is no inertia switch in this vehicle. And where did I say I condone the direct wiring? I don't get where the h*ll your coming from.

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Ok .. what do you get from this///// " ....... and then we cut all 3 of the factory wire's and wired them directly up to the fuel pump and got fuel pressure so we started the truck and let it run for like 5 to 10 minutes while we ......." ////// Those 3 wires are the input to the Pressure sw, the return and the pump power from the pump relay .. by him going directly to the pump motor he bypassed the pressure sw ... if he did that then the pump will draw excessive current because it has probably 20- 40 PSI on the pump (when you first start up the pump is unloaded and draws little current) if that's what these guys did ,and that's the impression I get from what they said ... the only reason the car stopped was they probably blew either the pump, the fuse or the interconnection internal wiring. I could care less what advice anyone gives ,, except when it comes to a potential tradgedy


Sorry if I woofed loud but if you think about what these guys did I'm afraid someone else may think that it's ok to do what they did


Sure I agree, and I said I didn't condone that, never did. I took it as you where implying this on me. And the fuel pump will put out 80 to 90 lbs at a dead head check. Fuel pressure should be 56 to 63 lbs checking at the Schrader valve. Maybe I miss understood what you said, you clarified it more. More enjoyable working with someone than against.


Ya ..thanks for sticking with this and having a happy ending. I've been following your posts for a few years and have great respect for your knowledge Tom


Thank you Tom, that means a lot. I do make mistakes for what ever reason, and certainly do not mind when someone corrects my answers, as long as there right because I do a lot of research. A lot of us work together on solving problems and makes this sight a good experience for people in need. Feel free to barge in any time as you also have a word of knowledge to offer.

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