Does fuel pump turn on temporarily when key is ON?

[rothsean]

My new fuel pump usually turns on when I turn the key to the ON position, and would run for a few seconds. Is that normal?

If so, it is not doing that anymore and car won't start.

[Silverbullet]

yup... normal... you can cycle it a few times, if you have not started your car for a long time... It helps...

[Shep]

My new fuel pump usually turns on when I turn the key to the ON position, and would run for a few seconds. Is that normal?

If so, it is not doing that anymore and car won't start.That's the fuel pump "priming". Happens on most cars, but if yours isn't doing that anymore and won't start (but does turn over), that's the most logical thing to test.

There's three things you need to run a non-diesel internal combustion engine: fuel, air, and spark (diesel doesn't need spark). It sounds like the first one is causing issues, so I would run some tests on the fuel pump and go from there.

[jawn101]

The priming at key-on is a function of the RPM relay, and the original mechanical ones are notorious for sometimes doing it, sometimes not. My factory one didn't do it, ever. My mechanical replacement did it sometimes, but not always. The only one that will always do it all the time is Dave's electronic one, which I now have.

The lack of prime in and of itself should not cause a failure to start, but they may both be symptoms of the same issue. What happens when you try to start? Have you tried jumping the RPM relay to see if the pump runs? Maybe the pump or some ancillary electrical device (ground, fuse #7) is dead.

[rothsean]

I jumped the relay and the pump does not work either, it just makes a very weak sound (humming), unlike the normal sound that it should make.

In addition, I removed the fuel fitting on top of the cold start valve to see if there is a flow of gas when cranking, nothing, not one drop.


Here is the crazy part, this new all-in-one unit was installed yesterday to replace my previously new all-in-one unit that was a month old but had a bad check valve...

ARG!!!


Is there anything that I am missing or should check? Jumped relay, done, did not work and no gas flow. Turned key to on, nothing. I can try to start the car and the only time it tries to kick over is if I spray start fluid in the intake box. The cold start valve fuel fitting should have gas flow all the time when the pump is on right?

[Shep]

Is there anything that I am missing or should check?Gas? It almost sounds like the gas gummed up, which may cause premature failure of the fuel sender. If the gas is fine, more than likely you got a bad fuel sender. In that case, talk to your vendor about a replacement unit.

[Dangermouse]

Wasn't your car at DMCH yesterday?

Obvious question: there is gas in the tank, visually verified?

[rothsean]

Wasn't your car at DMCH yesterday?

Obvious question: there is gas in the tank, visually verified?

Yep, it was at DMCH yesterday. It has 6 gallons of new gas in it.


I just can't think of anything to check. It still does not come on and there is no flow of gas to any of the fuel fittings.

[TTait]

Check the rollover switch under the dash near the hood release lever... Its unlikely that's the problem, but its a really quick thing to check...

If you put in a new fuel pump yesterday, and today its not turning on - it either blew the fuse, wiring is bad, or the new pump is dead.

[Bitsyncmaster]

What does your battery voltage read? That connector (two pin) to the fuel pump is a cause of a lot of these problems. Does the new pump installation remove that?

[David T]

Start by verifying battery voltage on the fuel pump and a good ground. Jumper the RPM relay if you have to. Other possible sources of a problem getting voltage to the fuel pump:
Bad connection at a connector up inside the washer bottle on the wiring harness.
Melted #7 fuse or connectors.
Bad inertia switch.
I suppose it is also possible you have a defective fuel pump. For testing purposes you could run 2 wires directly from the battery to the fuel pump and see if you can get it to run. The motor won't (can't) run AT ALL if the fuel pump isn't running. It is really amazing how quickly the motor will stop when the fuel pump stops. Just like flipping a switch!
David Teitelbaum

[rothsean]

When I jump the relay the fuel pump makes a sound but it is just an abnormal quiet humming sound that is not normal. My previous pump (new all-in-one unit #1) made a normal sound and so did this one for the first day. Now all of a sudden it makes a quiet hum.

Kind of like if you turn power on to a fan and hold the blades so it can't move, you can still hear the motor slightly.

[rothsean]

Tell me if I am correct: If the fuel pump is working properly and no lines are clogged, I should have good fuel pressure when I undo the cold start fuel line??

[DMC3165]

My guess is the pump is no good. It sounds like these new all in one units aren't quite what they're cracked up to be.

My suggestion is if you have the original pump. Swap it out and see if it runs. Odds are that sounds like your problem.

[ccurzio]

When I jump the relay the fuel pump makes a sound but it is just an abnormal quiet humming sound that is not normal.

I don't agree. The new pump is a LOT quieter than the old ones. "Quiet humming" sounds about right for its normal operation.

[Ron]

Tell me if I am correct: If the fuel pump is working properly and no lines are clogged, I should have good fuel pressure when I undo the cold start fuel line??
Sounds like it could be locked up...that's how a lot of those type do...
I'd take the quick connect off the output port (large one), put a hose on it and run it into a can to see if it was pumping instead of messing with wires, especially since it is making a sound...




Tell me if I am correct: If the fuel pump is working properly and no lines are clogged, I should have good fuel pressure when I undo the cold start fuel line??
If the pump is running there should Primary Pressure there (~76psi), and Rest Pressure when you shut it off (~48psi at first, then at at least 25psi at 10 min).
Of coarse, if you undo the cold start valve fuel line, you will have zero pressure and a messy fire hazard :flamed:

[rothsean]

I don't agree. The new pump is a LOT quieter than the old ones. "Quiet humming" sounds about right for its normal operation.

My recent new pump made a normal sound and so did this one the day that it was new. Now it makes a totally different sound and is a quiet humming sounds. Different than it was on day one and different than the previous 2 pumps (1 original and 1 new unit).