First problem happens when engine is cold

Tiny
ANONYMOUS
  • MEMBER
  • 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
ASEMASTER6371
  • EXPERT
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
Was this
answer
helpful?
Yes
No
Tuesday, February 12th, 2013 AT 11:41 AM
Tiny
SOSUEME
  • MEMBER
Thanks for the quick response.
Both have been checked and are operating properly.
Was this
answer
helpful?
Yes
No
Tuesday, February 12th, 2013 AT 6:53 PM
Tiny
ASEMASTER6371
  • EXPERT
What was the fuel pressure and what was the back pressure readings?

Roy
Was this
answer
helpful?
Yes
No
Tuesday, February 12th, 2013 AT 7:22 PM
Tiny
SOSUEME
  • MEMBER
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.
Was this
answer
helpful?
Yes
No
Tuesday, February 12th, 2013 AT 8:43 PM
Tiny
SOSUEME
  • MEMBER
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.
Was this
answer
helpful?
Yes
No
Tuesday, February 12th, 2013 AT 8:46 PM
Tiny
ASEMASTER6371
  • EXPERT
Needs 15 lbs to run properly.

What is the back pressure?

Roy
Was this
answer
helpful?
Yes
No
Tuesday, February 12th, 2013 AT 9:10 PM
Tiny
SOSUEME
  • MEMBER
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?
Was this
answer
helpful?
Yes
No
Tuesday, February 12th, 2013 AT 9:16 PM
Tiny
ASEMASTER6371
  • EXPERT
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
Was this
answer
helpful?
Yes
No
Tuesday, February 12th, 2013 AT 9:18 PM
Tiny
SOSUEME
  • MEMBER
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
Was this
answer
helpful?
Yes
No
Tuesday, February 12th, 2013 AT 10:06 PM
Tiny
ASEMASTER6371
  • EXPERT
Fuel pressure remains the same at all times. Does not vary.

Needs to be 15 lbs

Roy
Was this
answer
helpful?
Yes
No
Tuesday, February 12th, 2013 AT 11:05 PM
Tiny
SOSUEME
  • MEMBER
Ok. Thanks roy.
Is there a way to test the fuel pump with a multimeter to verify if thats the problem before lowering the tank and replacing it?
Was this
answer
helpful?
Yes
No
Tuesday, February 12th, 2013 AT 11:47 PM
Tiny
ASEMASTER6371
  • EXPERT
No, you need a pressure gauge to verify the pressure. Make sure you use a ac/delco new pump

Roy
Was this
answer
helpful?
Yes
No
Tuesday, February 12th, 2013 AT 11:49 PM
Tiny
SOSUEME
  • MEMBER
I have a pressure gauge thaat reads 10-11 psi. Is there a way I can isolate the cause of the low pressure before just guessing and replacing parts that may not need replacing?
Was this
answer
helpful?
Yes
No
Tuesday, February 12th, 2013 AT 11:55 PM
Tiny
ASEMASTER6371
  • EXPERT
You are not guessing as the pump produces the pressure. It is not up to specs most likely from the pump itself.

Roy
Was this
answer
helpful?
Yes
No
Tuesday, February 12th, 2013 AT 11:58 PM
Tiny
SOSUEME
  • MEMBER
Could something in between the fuel pump and the engine be at fault? I.E pinching fuel line. Clogged fuel filter. Fuel pressure regulator. Ect.

Im not suggesting this in a "you are wrong im right" way. You are the expert and ill most likely be replacing the pump to start with like you suggested. Im just trying to cover all the bases before I do.
Was this
answer
helpful?
Yes
No
Wednesday, February 13th, 2013 AT 12:04 AM

Please login or register to post a reply.

Recommended Guides