1977 Chev K10 fuel/carburetor trouble

Watch this, especially around 2:20 in- https://www.youtube.com/watch?v=sml0Ur9Csf8

Yes @texases that would be one way… But what I am after is to see it function before the fuel pump has a opportunity to fill the bowl. There should be fuel in the bowl ready and waiting for the accel pump to squirt… It is a way for me to try to determine if his bowl is draining while it sits.

Do the accel pump test before running… and then again after running… Two tests… If it has nothing to pump before the engine is run then the bowl is emptying while the vehicle sits…which is No Bueno.

If it can pump fuel after he gets it running it shows that the accel pump itself can function and that its fuel supply is the issue at hand.

Savvy?

I just checked the factory service manual for my 1960 Chrysler, it calls for 5-7 pounds, but that pump feeds two big four barrel carbs.

Re fuel pump pressure, I believe that by 1977 Chevrolet was using a fuel pump with a third connection which went to a fuel tank return line where a pressure relief valve kept fuel flowing back to the tank to keep the fuel cool and also keeping fuel pressure below 3 psi. I no longer have the old factory manuals so I’m again shooting from the hip.

It’s been my experience that when the float bowl on a QJ is empty the cause is generally a leaking jet well plug.

It’s also my experience that most carb overhaul kits do not contain a new plug and epoxy. The trick then is finding a parts counter person that knows what you’re talking about.

My accelerator pump failed a few years ago. It didn’t cause a problem starting but caused the idle to go high. To replace it I had to buy a carburetor rebuild kit. Not wanting anything to go to waste I replaced every part the kit came with. It cost more than the fuel pump and was a much harder job.

I figured out the accelerator pump was bad by working it manually: it leaked gas. You can do this with the engine off.

I’ve had similar problems on my similar era Ford truck. Found several different problems over the years

  • sticking fuel inlet valve in carb
  • leaking power valve in carb
  • leaking accel pump in carb
  • faulty fuel pump

I’d start by measuring the fuel pump flow rate during 10 seconds of cranking. Then pop the top off the carb and seeing how much fuel is left in the bowl when then happens. Gasoline evaporates from the bowl over time, and if anything (faulty venting system etc) is allowing it to evaporate more than it should this could result too. My guess is a leaking power valve.