Author Topic: Need help with a hot start issue  (Read 2077 times)

Offline johnt365

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Need help with a hot start issue
« on: May 31, 2011, 06:44:00 PM »
I have a small block chevy with headers, alum heads and intake and my Qjet carb.  My car runs perfectly after the rebuild help from Cliff.  It starts up with no problem most times EXCEPT when it is hot outside and it has been run for a while. 

Once it is hot if I shut it down it can be hard to restart.  The motor spins fine.  Also, when it wont start, I have removed the air cleaner and verified that fuel is coming out of the accelerator pump.  So there is fuel in the bowl.  I have installed a heat shield and non conductive gasket. 

I thought the issue may be the remnants of the winter fuel formula with a low boiling point.  That should not be an issue now.  If the issue is the ethanol in the fuel lowering the boiling point, wouldn't more people be having this issue?

Is this issue worse for Qjet carbs or is there something I can try to overcome it? 

Thank you for the suggestions.
John

Offline omaha

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Re: Need help with a hot start issue
« Reply #1 on: June 01, 2011, 02:57:29 AM »
   I know this has been a common problem for a lot of people and not just the Q-jet guys. Maybe one of the most common problems nowadays. I had this problem on my pontiac motor and it turned out to be heat soak in the fuel pump.I switched to a mechanical pump and ran the fuel line a different route that was farther away from the engine. I also used fuel injection hose instead of the steel line because it insulates the fuel better. it worked. If you could figure a way to get rid of that heat under the hood that would be good also.An electric pump works it just can not get hot. same goes for fuel lines. tiny bypass is anither idea to help with the vapor lock. It seems like accal pump shot would start the engine but that is not always the case when the engine is hot.   BTW, that fuel injection hose (9R I believe) is PRICEY.
   After it gets hot, if you let it cool down, how does it start then? IMO, fuel vapors must be minimized as much as possible with this crap that they call gasoline these days. Sure it works just fine with fuel injected cars with 44 psi line  pressure and bypass systems and fuel injection. Carbs with low PSI and no bypass (to keep the fuel cool) is not so good. Also, if you still got the mechanical pump on it, remember the quality of the pumps has gone down hill in some cases due to decreased demand for them. So, just some things to ponder. my .02

Offline slowpoke

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Re: Need help with a hot start issue
« Reply #2 on: June 06, 2011, 05:55:35 PM »
i had the same problem on a holley carb and added a phenolic spacer/insulator and it solved the hot start problem.