First problem happens when engine is cold

Tiny
ANONYMOUS
  • 1991 CHEVROLET CAPRICE
  • 142,000 MILES

First problem happens when engine is cold. Second problem happens randomly and intermittenly.
but I think they are both related.

first problem.
2-5 seconds after acceloration, the engine bogs down to about 100-200 rpm. And sometimes dies. But most of the time as long as I step on the gas a little harder, after 1-2 seconds it goes right back to normal acceloration as if nothing happened.

second problem
this happens randomly. I cannot pinpoint any conditions it happens more or less under. But if feels sluggish at times. For instance ill try to accelorate to speed up, (rpms seem normal for how much/little im pressing the gas) but it will feel like im not pressing on the pedal at all. Sometimes it takes as much as a full minute to get from 15-70 (getting on the freeway)

Tuesday, February 12th, 2013 AT 6:38 AM

15 Replies

Tiny
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Have the fuel pump pressure checked. For both issues.

Have the back pressure checked for cat converter for both issues as well. If the engine canot breathe it will act like this

Roy

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Tuesday, February 12th, 2013 AT 11:41 AM
Tiny
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Thanks for the quick response.
Both have been checked and are operating properly.

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Tuesday, February 12th, 2013 AT 6:53 PM
Tiny
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What was the fuel pressure and what was the back pressure readings?

Roy

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Tuesday, February 12th, 2013 AT 7:22 PM
Tiny
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I do not recall either readings. I just know the mechanic I took it to checked and said both were fine.
He also replaced spark plugs. Cap/rotor. Map sensor. Needless to say he could not figure out what the problem was.

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Tuesday, February 12th, 2013 AT 8:43 PM
Tiny
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I have a permanent fuel pressure gauge on the fuel line right behind the injectors. But I cant see the reading while the problem is happening. It reads 10psi at idle.
I just sorta took the word of the mechanic that checked it.

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Tuesday, February 12th, 2013 AT 8:46 PM
Tiny
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Needs 15 lbs to run properly.

What is the back pressure?

Roy

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Tuesday, February 12th, 2013 AT 9:10 PM
Tiny
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I dont have anything to check back pressure. Like I said I just took the word of the mechanic that tested it.
Does the fact that it idles perfect at 10-11psi matter?

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Tuesday, February 12th, 2013 AT 9:16 PM
Tiny
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No, as it needs full pressure for above idle conditions.

Did he tell you it was ok? The back pressure? Sounds like you need a new shop.

If the cat is partially clogged, it will cause all kinds of issues.

Start with the fuel pump

Roy

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Tuesday, February 12th, 2013 AT 9:18 PM
Tiny
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He did tell me it was ok.
The fuel pump was replaced about 2 years ago. How long do they usually last?

Will the fuel pressure go up if I rev it in neutral? Or does it have to be actually driving? If it will go up at idle with the gas pressed then I can stand outside and watch the gauge while someone is inside the car pressing the gas

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Tuesday, February 12th, 2013 AT 10:06 PM
Tiny
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Fuel pressure remains the same at all times. Does not vary.

Needs to be 15 lbs

Roy

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Tuesday, February 12th, 2013 AT 11:05 PM

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