The Stovebolt Site Forums The Shop Area Engine Shop Same engine problems

Hi folks,
In a previous post on carburetor trouble I received some good pointers on trouble shooting which I followed and still have the same problem.The truck will not run at idle or on the road unless the choke is almost all the way out. I bought a container of carb. cleaner and after tear down and a good soak I blew all the passageways out and reset the float, reassembled and tried it with the same results.I can get a new carb for around 180.00 bucks and at this point I surely am tempted. I'll take any and all ideas or suggestions to get her going. I don't like to admit defeat but I'm getting close.

Thanks,
JMH

Have you checked for vacuum leaks? Check the manifold gaskets, both at the head and carb flange, plus any lines comming from the manifold (wipers, power brakes, vacuum advance). You may also want to check any component that is run using engine vacuum for laking or ruptured seals.

I had a similiar problem. The gas tank pick up tube was pluged and not getting gas. Make sure the gas line is open. You may have water in the tank, that is what plugged the pick up tube.

The carb you've got now is probably in better shape than any "rebuilt" you can buy, assuming it's the right application for your engine in the first place. Since your other thread on this subject says it runs OK with the electric pump, better check out the mechanical pump to see if maybe you got a lemon- - - - -it happens! Remove the fuel line at the carburetor, and run the gas into a catch container of some sort. Start the engine and let it idle- - - -it should run for a minute or more on the fuel in the float bowl, and measure the output. A good pump will produce at least a pint in 30 seconds. Now, check the pressure: deadhead the pump into a fuel pressure gauge, and run the engine. The pump should produce 2-4 PSI, minimum, and the pressure should hold for 30 seconds or so after you shut the engine down. On the inlet side, attach a vacuum gauge, run the engine, and look for 12-15 inches of vacuum, and a "hold" for a few seconds after shutdown. A failure of the volume test with good results otherwise should send you looking for a restriction upstream of the pump like a clogged fuel tank pickup, collapsed flex line, air leaks between the tank and the pump, etc.
Jerry

I don't remember what carb or truck model from the last post. If your fuel delivery system checks out OK you may need to try a larger main metering jet. When rebuilders rebuild these carbs they mix up parts.

Hi All,
Thanks for all the tips and advise. I talked with a neighbor who unknown to me is an old hot rodder and used to hot rod these old engines. He told me the vacuum advance must visibly move the distributor when you rev up the engine. Mine does not move at all hence a bad vacuum advance for all the lines are clear and I am getting good vacuum at the carb. I have ordered one from a vendor and after install I will post my results. Sure hope this does it for I have exhausted all other options.

Later,
JMH

I don't think this is a symptom of a bad vacuum advance.

No, but it the classic vacuum leak symptom. Perhaps a ruptured diaphragm in the advance?

Possible.