Cranks but will not start

CHRIS EARLEY MOSHER

MEMBER
1989 PONTIAC FIREBIRD
5.7L
V8
2WD
AUTOMATIC
210,000 MILES

Well, I have had a pretty bad oil leak for a while now and this week I decided to fix it. It was my oil sending unit plug. I forgot to unplug the battery and when I cut the hot wire it sparked a little nothing terrible. So I unplugged the battery finished installing the new plug and thought everything was fine, but when I went to start it it just cranked which is very weird for this car has been very good to me. I have a vats bypass in it so I use a push start. Well, I went ahead and removed the bypass and repaired the vats problem hoping that was it still nothing, but I am happy I could crank it with the key for the first time since I got it. We have checked fuses and such but I do not smell gas when cranking. So it feels like it gets no gas but it does start up for a quick second when I put starter fluid in it.

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

HI and thanks for using 2CarPros. Com.

It sounds like you are correct. It is not getting fuel. I am not sure what wire you cut which sparked. If the ignition was off, there should not have been power to the oil pressure switch.

Since you have already confirmed it's not getting fuel, lets start easy. I have attached a engine compartment view of the vehicle. I need you to first locate C-9. Take a look at the picture for location. This fuse is for the fuel pump and ECM. You may have blown it when you shorted the wiring.

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Next, the fuel pump relay can be an issue. However, I question that it could have been damaged. Here are directions for replacement as well as location and pictures.

Note: The fuel pump relay is located in the engine compartment, attached to the multi-use bracket on the upper dash panel extension. Other than checking for loose connections the only service on the fuel pump relay is replacement.

Procedure:

Verify that the ignition switch is in the "off" position.
Disconnect the wiring harness plug.
Remove the fuel pump relay.
Install the new fuel pump relay.
Connect the wiring harness plug securely.

Lets start with that for now. I have a feeling the fuse for the ECM/fuel pump blew.

Let me know what you find or if you have other questions.

Take care,
Joe

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Thursday, June 21st, 2018 AT 8:25 PM

CHRIS EARLEY MOSHER

MEMBER
2 POSTS

You were correct on the fuse blowing I replaced and it started up but now I think the fuel pump motor actually went out because it will not start again. When I do get fire I have to continuously pump the gas pedal to keep up rpms.

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Thursday, June 21st, 2018 AT 10:38 PM

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi Chris.
Chances are the pump is not bad; however, it would not be a bad idea to test it for pressure. Here are general directions for testing a fuel pump:

https://www.2carpros.com/questions/engine-cranks-but-wont-start-44987594#last

I have attached a chart listing all fuel pressure specs for this year vehicle. I believe the 5.7 is the last one.

Now, keep in mind, the ECM may have been affected as a result of the power loss or surge. What I need you to do is check for trouble codes. If a code 51 comes up, we may need to have the ECM reprogrammed. Here are directions for getting OBD 1 codes.

Here are directions on how to retrieve the codes on your vehicle:

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

Please keep in mind, the vehicle may need to be run for some time for the system to reteach itself.

Let me know what codes you find or if you need help with anything.

Take care,
Joe

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