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1998 GMC Sierra 4x4 5.7lt V8


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05-31-03, 01:36 PM   #1  
nfailla
1998 GMC Sierra 4x4 5.7lt V8

I would appreciate any advice in rectifying the following problem. This week the vehicle would not fire twice as if it were not getting fuel. Also, it would bog down at times.

Today it will not fire at all. Just keeps turning over. I have changed the fuel filter today and checked the relay. Still no luck. Any ideas. I have a feeling it is the fuel pump but that sounds like a difficult job.

Any advice?

 
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darrell McCoy's Avatar
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05-31-03, 02:04 PM   #2  
darrell McCoy
have you checked fuel pressure to determine if you have fuel getting to the engine?

 
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05-31-03, 04:34 PM   #3  
Joe_F
Start with the links and posts in my signature file below.

 
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06-01-03, 07:34 AM   #4  
How did you check the relay?I would be more concerned about fuel pressure as Darrell suggested. On your truck losing 5 psi will cause a no start/hard start condition.Will it start right away if starting fluid is introduced in the intake stream?If it does replace the pump.Be careful however to inspect the electrical terminals at the pump connector if they are not shiny brite they
are BAD.Many pumps have failed due to this,slight browning of the terminals,a bright light is required to see this problem.

 
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06-02-03, 11:02 AM   #5  
nfailla
Thank you

Thank you for the advice! After a little more research I found tht there is a switch involved with oil pressure. I recently had the oil system flushed and noticed at this time I was getting low on oil. It was time to change my oil this weekend so I did not add more oil.

However, after finding out about this switch I added oil and the problem was rectified. The only thing is I got the impression from my research that the swich that is in conjunction with oil pressure is an override switch in case the computer doesn't tell the fuel pump to start. Do I still need to have the computer module checked? Was my understanding of this switch correct?

Nick

 
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06-02-03, 12:15 PM   #6  
Joe_F
Find the cause of the low oil problem first!

 
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06-02-03, 01:25 PM   #7  
darrell McCoy
Switch? Are we talking about an oil sender swx or a low oil light swx? A big difference. I believe on a lot of GM's, after you change oil the low oil light switch must be reset. Should say in owners manual if this applies. Plus procedures. Unless it has changed, fuel pump will run on startup then current to pump reverts from key run mode to contact thru the oil pressure sending swx. A safety factor. Joe can correct me on this if I am wrong. However as Joe sez, you need to find where the oil is going.

 
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06-03-03, 05:38 AM   #8  
Joe_F
We would have to go back to the original problem and how it was diagnosed. Always have to go back to the basics.

Was it lacking fuel, air, spark or both?

 
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