1978 GMC Carburetor problem (I think)

COBEERTOAD

MEMBER
1978 GMC SIERRA

This problem has me stymied.
1978 GMC Sierra 350ci a lot of miles
I hit a large pothole and the truck quit running. Found that the carb kept flooding. Anyway, replaced the carb with a rebuild 'cause I was too lazy to fix the problem. The truck would not start. Fuel was not getting into the carb. Even tried taking the filter out and it still would not get fuel into the carb. Took the carb back and got another one. Well, same problem.

After attempting to start the truck, when I disconnect the fuel line, there is quite a bit of pressure there, so I am under the assumption that the fuel pump is operating properly. It is kinda' new too. When I pour fuel directly into the carb it starts up with no problem. I know I am missing something here, but have not come up with any ideas.

Any assistance would be greatly appreciated and I would be sure to show my appreciation with a large donation. (Large being large for me. Remember I drive a 1978 GMC as my primary vehicle.) Thank you.

3 Replies

COBEERTOAD

MEMBER
5 POSTS

Bump, just to see if I'm being ignored.

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Tuesday, April 24th, 2007 AT 3:22 AM

BURRBRIAN

MECHANIC
158 POSTS

Well, if the pump is putting out gas in the line to the carb but not getting through the carb that seems to narrow it down to something clogging the line close to the carb or the floats in the carb need to be set for the carb to run. What kind of carb is it? Check the needle valve in the fuel bowl to make sure it opens to let fuel in the carb. Keep looking in the general area and you should find the bug in there somewhere. Or if you don't want to mess with it yourself bite the bullet and take it to some one who knows what they are doing with cars and pry open the wallet. :Roll:

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Monday, May 7th, 2007 AT 8:21 PM

COBEERTOAD

MEMBER
5 POSTS

Forgot I had this posted. Thaks for the reply, unfortunately, the worst possible thing that could happen, happened. I had a friend come over to look at the truck. He said to turn it over so he could get an idea of what the problem was. I turned the key and the truck started right up. I was cranking it that morning to make sure that the battery had not discharged and it never came close to starting. So I have no idea what was wrong other than what you stated and perhaps if it was clogged, it fixed itself or if the needle was stuck, same thing. I would have rather him told me the engine was blown so I would at least have an answer. It's been a over a week and I have had no problems with it.

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Tuesday, May 8th, 2007 AT 4:21 PM