Wont start when hot
Thread Starter
Instructor
Joined: Apr 2025
Posts: 156
Likes: 44
Wont start when hot
Hey Guys, Sorry if this is an old question. My ‘71 350 4spd, has the original rebuilt Q jet. Cold start ups are fine, ( pumping the gas ) after it’s driven for any length of time if you shut it off, then immediately go to restart it, it won’t. It stutters then just cranks ( fast, not slow ). If I give it a shot of ether it starts right up. What’s going on? A friend of mine suggested a Carb, or manifold plate that will prevent this from happening? He also suggested switching to an electric fuel pump for better reliability.
Any suggestions/thoughts? Thanks, Steve
Any suggestions/thoughts? Thanks, Steve
Melting Slicks
Joined: Feb 2018
Posts: 2,322
Likes: 720
From: Marietta GA
I have a car show buddy that rebuilt his Quad several years ago. He is a very competent repair guy … who has been fixing business copiers for more than thirty years. His carb works great until he tries to start the car when he has driven somewhere and the engine is hot. It would take an hour to list all the things he has tried to remedy the problem, eventually ruining the fitting for the fuel line that comes from the fuel pump. The truth is, that he is stubborn and would not send his carb to Lars. There are certain things that we can’t fix on our cars, and the Quadrajets are one of them. Their internal Parts are old, worn, and maybe not even the right ones. Who knows how many people like my buddy have tried to “REBUILD” them. Be smart don’t wast your time and money doing it yourself.
Race Director
Joined: Mar 2016
Posts: 14,337
Likes: 8,140
From: Napa Valley California
It could be several different things regarding your warm start problems.
You can simply check them at no cost.
It could be the coil is starting to fail, it could be the ignition module if you have an hei distributor, it could be the battery ground cable, it could be the fuel is boiling in the fuel bowl also known as vapor lock, or it could be the carb itself.
Check and do the simple, cheap things first.
If you suspect it’s the carburetor itself, contact Lars and work with him on identifying that you have the correct carb for your car or if you’ll need to find a correct replacement for him to rebuild.
Lars is the best in the world at rebuilding a QJet.
You can simply check them at no cost.
It could be the coil is starting to fail, it could be the ignition module if you have an hei distributor, it could be the battery ground cable, it could be the fuel is boiling in the fuel bowl also known as vapor lock, or it could be the carb itself.
Check and do the simple, cheap things first.
If you suspect it’s the carburetor itself, contact Lars and work with him on identifying that you have the correct carb for your car or if you’ll need to find a correct replacement for him to rebuild.
Lars is the best in the world at rebuilding a QJet.
Melting Slicks
Joined: Sep 2016
Posts: 2,213
Likes: 970
From: Wauconda IL
What is your procedure for starting it when warm? Are you hitting the gas pedal when warm? Most times on a warm engine you just hit the key without touching the gas pedal and it fires right up. You stating the warm engine fires right up after spraying starting fluid kinda tells me it's flooded.
Last edited by sunflower 1972; May 2, 2025 at 11:16 AM.
Drifting
Joined: Aug 2019
Posts: 1,334
Likes: 225
Obviously shooting ether and it starts indicates a fuel issue. When it doesn't start, is the choke blade fully open? Maybe when you spray the ether, you're opening the choke flap. If you move the throttle lever, do you see fuel coming out of the nozzles?
One other check to see if the float level is too high, after the vehicle runs for a while, shut it down and look down the carb throat. If you see fuel leaking into the throat, then your level is too high. Just a start. Good luck!
One other check to see if the float level is too high, after the vehicle runs for a while, shut it down and look down the carb throat. If you see fuel leaking into the throat, then your level is too high. Just a start. Good luck!
Pro
Joined: Nov 2023
Posts: 699
Likes: 335
From: Aubrey TX
Have you been able to verify if the carb is original and not a hodge podge of different carbs put together to barely operate as one? @Lars can help with that. Im still amazed when someone posts a photo of a Qjet and Lars can tell if the base, body, and top were from different carbs or not.
