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BOBBYSS
BOBBYSS, Master Technician
Category: Chevy
Satisfied Customers: 17229
Experience:  ASE MASTER CERTIFIED, AA DEGREE AUTO/DIESEL TECH
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Ok so ive been stumped 2 weeks trying to figure out this

Customer Question

Ok so ive been stumped for about 2 weeks trying to figure out this fuel pump issue.. It does not want to prime when i first turn the key, and my fuel gague shoots to full, but when i jump the relay it instantly kicks on (replaced relay and no luck) i also did a light test and no power is getting to pin 30 even when the key is turned, the only one that lights up is pin 86 also the whole fuel pump assembly is brand new, thanks
Submitted: 1 year ago.
Category: Chevy
Expert:  BOBBYSS replied 1 year ago.

Hello, my name is***** for the question. Can you tell me if this problem started all of a sudden?

Customer: replied 1 year ago.
actually it was all of a sudden, never had a fuel issue before this.. I was over my friends and my car sat in the rain for about 30 min when i got back in it barely started and idled weird, then later wouldnt start at all thats when i noticed the pump doesnt kick on, i sent the pcm off thinking it could of got wet but they said its working perfect, its not throwing any codes either
Expert:  BOBBYSS replied 1 year ago.

Will it kick on when cranking the engine over?

Customer: replied 1 year ago.
No wont turn on at all unless relay is jumped thats the only way ive been able to get it turn on
Expert:  BOBBYSS replied 1 year ago.

Thank you. It sounds like you have an issue with the control circuit. It may be a faulty ignition switch. This is very common. Do you have a voltage meter to run through some tests?

Customer: replied 1 year ago.
I have a test light no volts meter tho, did u have any other thoughts?
Expert:  BOBBYSS replied 1 year ago.

If there are not any volts at the control circuit for the relay then you need to see why the computer is not sending a voltage signal. Either the PCM is failing or there is an issue with the ignition switch. Does the check engine light come on when the key is turned on?

Customer: replied 1 year ago.
No check engine light i plugged in an ob scanner and it had no codes vats is working properly too im assuming cuz the security light comes on then goes off after a couple seconds when key is on
Customer: replied 1 year ago.
Not sure why but when my gas gauge started acting up so did my fuel pump, im thinking its a ground or some wiring issue, the car is bonestock no aftermarket mods, the assembly and relay are all brand new, fuses are good too
Expert:  BOBBYSS replied 1 year ago.

If the check engine light is not coming on when the key is first turned on then the PCM is either not getting an on signal or the PCM is failing. I would check the power at the PCM before going any further.

Customer: replied 1 year ago.
What does that mean if i dont get a check engine light when the key is turned
Customer: replied 1 year ago.
Should the pcm be replaced?
Expert:  BOBBYSS replied 1 year ago.

This means that the PCM is not powering up and going through a self check.

Customer: replied 1 year ago.
How can i check the power at the pcm
Customer: replied 1 year ago.
Also the green back light for the gauges nor my radio light up anymore, is that linked to the pcm too?
Expert:  BOBBYSS replied 1 year ago.

The more information that you are giving me sounds more like a failing ignition switch. It does not sound like it is giving the on signal.

Customer: replied 1 year ago.
Would a bad ignition cause the gas gauge to shoot full?
Expert:  BOBBYSS replied 1 year ago.

It can cause it if you are constantly getting a cycling signal from the switch which causes the gauge check to occur. If you have a voltage meter I can tell you what to check on the switch.

Customer: replied 1 year ago.
Now my lighting is working again green back light comes on and so does my radio but still no check eng light on
Customer: replied 1 year ago.
Like i said before, the pcm did get wet but i sent it off and they said it was good, idk what tests they did but i have a feeling thats the issue
Expert:  BOBBYSS replied 1 year ago.

It can possibly be the PCM, but there are some circuits involved that it does not control. I really think you are better of starting with the ignition switch.

Customer: replied 1 year ago.
How can i check the power at the pcm and the ignition
Expert:  BOBBYSS replied 1 year ago.

You will need a voltage meter. Do you have one?