Can a fuel pump b bad even though it's primes and turns off

50

Asked by Dec 23, 2015 at 07:44 AM about the 1999 Chevrolet Blazer LT 4-Door 4WD

Question type: Maintenance & Repair

13 Answers

22,310

Yes it can could be something mechanically wrong with the pump the only way to tell is to do a fuel pump pressure test or just spray some starter fluid or throttle body cleaner into throttle if vehicle starts then shuts off most likely the pump but still best to do the test.

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83,865

Fuel pressure should be 56 to 62 lbs.

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50

Oh it's at 40lbs does not leak down won't go higher even trying to turn key on and off

83,865

To verify it is the fuel pump, do a dead head test, fuel only running into the fuel pressure gauge. That should be 63 lbs at least.

1 people found this helpful.
50

How do I do that?

83,865

Well, just the line running into the fuel pressure gauge and not threw it. One way into the fuel pressure gauge. Usually done at the fuel filter. May need some more different fittings. Or still hook up at the schrader valve, but have to block the out going fuel.

1 people found this helpful.
50

Tks the gauge I rented has all the fittings I'll give it a try

83,865

40 lbs is low fuel pressure, but you said it held there, so indications are that it is the fuel pump, but I wanted you to be sure, since the gas tank would need to be dropped to replace.

1 people found this helpful.
50

I no I put one in 5yrs ago of course it quit after I had filled up, had to siphon 15 gal b4 I could drop it. I'll spend more for a better pump this time. The gas gauge hasn't been working either any ideas if I need to do the pump

83,865

I say yes because you said you checked 40 lbs. and it should be 56 to 63 lbs. I was just letting you know how to verify positively that it is the fuel pump. There may be other fuel issues but not showing at this point. Need to have the 56 to 63 lbs to do a bleed down test for indications of other problems. So far 40 lbs bleed down test you did things look ok. I would get a good new fuel pump, and since you are there, you get a new sending unit. This very well may fix the gauge.

1 people found this helpful.
50

Ok tks haven't had a chance to do anything yet

50

Changed the pump it comes as one unit with float sending unit all as one piece cranked right up. Tks for the help!!!

83,865

Sounds great! Thats what we like to here!

1 people found this helpful.

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