Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor
Low RPM Hot Restart
Frank400:
What is the carburetor number on that Jet carb ?
Cliff Ruggles:
We get calls in here all the time from folks who bought those and want us to crawl thru the phone and fix them. I don't really want any sent here, nor do we want anything purchased over the counter from an auto parts store. Much better end result to start out with an unmolested core and completely/correctly rebuild it exactly for the application....IMHO....Cliff
Nfg:
--- Quote from: Frank400 on March 30, 2017, 03:35:10 AM ---What is the carburetor number on that Jet carb ?
--- End quote ---
17083222
von:
I had the same problem and it turned out to be too much fuel pressure from a stock replacement parts store fuel pump, Airtex brand. I tried two of them with the same result. Stock 350 Chevy engine. I got an AC Delco pump from a Chevelle repro parts house and problem solved. I put a fuel pressure gauge and then a fuel pressure regulator on it to verify the cause. After it was shut off hot the fuel pressure would rise even higher for a little while, overcoming the needle and seat and cause flooding, which caused the hard start. If it would sit long enough for the engine to cool some, the pressure would drop enough and excess fuel in the intake would evaporate and engine would start OK.
Nfg:
--- Quote from: von on March 31, 2017, 02:08:30 AM ---I had the same problem and it turned out to be too much fuel pressure from a stock replacement parts store fuel pump, Airtex brand. I tried two of them with the same result. Stock 350 Chevy engine. I got an AC Delco pump from a Chevelle repro parts house and problem solved. I put a fuel pressure gauge and then a fuel pressure regulator on it to verify the cause. After it was shut off hot the fuel pressure would rise even higher for a little while, overcoming the needle and seat and cause flooding, which caused the hard start. If it would sit long enough for the engine to cool some, the pressure would drop enough and excess fuel in the intake would evaporate and engine would start OK.
--- End quote ---
Thank you for posting this. I had a Delco pump that was putting out 9 psi. Thinking that was the problem I installed a carter pump that is rated at 5.5 psi but really is just under 6 psi and still had the same exact issue. After reading your reply I hooked up the pressure tester and after shut down fuel pressure goes over 8 psi with in 10 mins.
My fuel lines are not close to any heat sources and running a plastic spacer. But I will install a regulator and see if it helps.
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