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I Know its a GM but i need help.


86_cookiemonster

November '08 STOTM Winner
MTOTM Winner
Joined
Aug 8, 2007
Messages
337
Vehicle Year
1986
Transmission
Automatic
I have a 1978 Trans-am with the Pontiac 400 engine in it. It is the 220 horse version, the one with the 350 heads. I have several serious problems with it. The first and by far the worst is the car has started hesitating really bad when I step on the accelerator. It will surge a little then eventually start to slowly accelerate. My dad was telling me that it might be the distributor. Any ideas what could be causing the problem.

The second problem is that the carb keeps clogging. I changed the fuel filter twice now and these little chunks of gunk, that kinda look like rat turds, keep forming inside it and clogging the primary metering jets. Any idea where these particles could be coming from?

This car was given to me by my grand-father, and is kind of a family heirloom, when it isn't running right it is really depressing not only for me but for my family. So any help would be greatly appreciated.

Thank you
 
I say drop the fuel tank and rinse it out or possibly buy a new one depending on its condition. Replace plugs, points, wires, cap and rotor and check the timing.
 
your rat turds in the fuel line could be the inside of a rubber fuel hose deteriorating.

Not sure where the fuel filter is on this beast, but I would replace any rubber hoses from the fuel filter to the carb.

Does this car have a mechanical fuel pump? the diaphragm might be deteriorating on it.. could be the cause of your hesitation..

AJ
 
your rat turds in the fuel line could be the inside of a rubber fuel hose deteriorating.

Not sure where the fuel filter is on this beast, but I would replace any rubber hoses from the fuel filter to the carb.

Does this car have a mechanical fuel pump? the diaphragm might be deteriorating on it.. could be the cause of your hesitation..

AJ

yes it has a mechanical pump. I replaced it about two years ago.
 
I say drop the fuel tank and rinse it out or possibly buy a new one depending on its condition. Replace plugs, points, wires, cap and rotor and check the timing.

your rat turds in the fuel line could be the inside of a rubber fuel hose deteriorating.

Not sure where the fuel filter is on this beast, but I would replace any rubber hoses from the fuel filter to the carb.

Does this car have a mechanical fuel pump? the diaphragm might be deteriorating on it.. could be the cause of your hesitation..

AJ

+1, id also check your air fuel mixture, my 73 blazer had the same deal after i rebuild the holly on it yesterday and i had to adjust the airfuel mixture beacuse it would bog bad when trying to step on it. these other two guys nailed what i was going to say dead on:icon_thumby:
 
Sounds like a weak accelerator pump w/the carb. Dont forget there's a fuel filter at the carb itself. To replace the acc pump diaphram requires the top of the carb to be removed. That old Quadrajet should be a piece of cake for ssomeone a little familiar w/carbs.
 
I agree with everyone, replace all fuel filters in and out of carb, all rubber hoses, pump (even though it's "only" 2 yrs old), check float level, do tune-up, make sure timing is good with a vacuum gauge not a timing light. Then go from there, nice freebie though.
 
I agree with everyone, replace all fuel filters in and out of carb, all rubber hoses, pump (even though it's "only" 2 yrs old), check float level, do tune-up, make sure timing is good with a vacuum gauge not a timing light. Then go from there, nice freebie though.

I checked the pump already, i know it is getting older. :P.

I will have to start replacing those lines.
 
i think i fixed it, the Accelerator pump wasn't seated right.thank you for your help.
 

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