Hot start issue- minor
Thread Starter
Burning Brakes
Joined: Aug 2000
Posts: 952
Likes: 0
From: Morgantown,WV USA
Hot start issue- minor
All,
I have a slight issue with my stock 78 L48 that I would like some advice on.
I have a SMI quadrajet on my stock L48 and the motor performs pretty well for what it is (185 hp isnt much) and all the plugs are reading fine.
The problem I am having is after driving the car on a hot day and parking it outside for a while (30 minutes or so) its difficult to keep running when it starts- almost acts like its flooding. I drove the car 120 miles yesterday in 90* heat and the water temp never exceeded 200* but when I went to start it after it sat it was difficult to keep running.
After the engine started I had to modulate the gas to keep it running but after 20 seconds it was ok.
In cooler weather it starts without a single turn of the motor and runs fine, but I am not sure if I have a case of heat soak and there is no cure.
I did slice a rubber piece of 3/8 fuel line and placed it over the matal fuel line that runs from the pump to the carb in an effort to insulate the fuel line from the heat of the intake.
Any input is appreciated!
I took a long drive yesterday to shake the car down in preparation for the Carlisle trip next week. It did great- cruised at 65mph with the air on while listening to an 8 track tape! Life is good.
Dan
I have a slight issue with my stock 78 L48 that I would like some advice on.
I have a SMI quadrajet on my stock L48 and the motor performs pretty well for what it is (185 hp isnt much) and all the plugs are reading fine.
The problem I am having is after driving the car on a hot day and parking it outside for a while (30 minutes or so) its difficult to keep running when it starts- almost acts like its flooding. I drove the car 120 miles yesterday in 90* heat and the water temp never exceeded 200* but when I went to start it after it sat it was difficult to keep running.
After the engine started I had to modulate the gas to keep it running but after 20 seconds it was ok.
In cooler weather it starts without a single turn of the motor and runs fine, but I am not sure if I have a case of heat soak and there is no cure.
I did slice a rubber piece of 3/8 fuel line and placed it over the matal fuel line that runs from the pump to the carb in an effort to insulate the fuel line from the heat of the intake.
Any input is appreciated!
I took a long drive yesterday to shake the car down in preparation for the Carlisle trip next week. It did great- cruised at 65mph with the air on while listening to an 8 track tape! Life is good.
Dan
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Thread Starter
Burning Brakes
Joined: Aug 2000
Posts: 952
Likes: 0
From: Morgantown,WV USA
Hot start issue- minor Reply to Thread
Are you going to Carlisle, Roger?
Dan
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Yes, the heat riser is hooked up but its working properly- I verified that. I left the car sit for 30 minutes and checked a few of the plugs and they were clean & dry. When you refer to leakage were you refering to fuel leaking into the cylinders upon shutdown? If so, I do not think that is happenning.
Are you going to Carlisle, Roger?
Dan
Are you going to Carlisle, Roger?
Dan
Some heat risers had a 1 way valve installed to keep them from rattling but it also kept them closed after warm up.
I'm not going to make Carlisle this year but a bunch of my parts are.
Thread Starter
Burning Brakes
Joined: Aug 2000
Posts: 952
Likes: 0
From: Morgantown,WV USA
Hot start issue- minor Reply to Thread
I feather it- I have never had to hold it down to clear it.
Its a shame you are not making the trip. I owe you a cold beverage...or two...or three...for all the help you have provide me.
Dan
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
similar conditions exist with Rochester FI units...for some reason the the fuel has become more susceptible to lower boiling temperatures....it then evaporates out of the carb from engine heat and causes momentary fuel absence on restarts as the pump temporally catches up to the engines requirements {boils at a lower temp}
Last edited by Ironcross; Aug 21, 2011 at 12:04 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Try loosening your fuel cap and see if that changes anything,I'm wondering if you have a bad check in the fuel pump,combined with vacuum in the tank might empty the carb in 30 min,feathering might keep the engine running until the bowl refills. Just a thought.
Thread Starter
Burning Brakes
Joined: Aug 2000
Posts: 952
Likes: 0
From: Morgantown,WV USA
Hot start issue- minor
Hmm feathering is working the accelerator pump,I don't think this would help if it was flooding. This might take some more investigating on your part to see what exactly the engine needs , more fuel or less.
Try loosening your fuel cap and see if that changes anything,I'm wondering if you have a bad check in the fuel pump,combined with vacuum in the tank might empty the carb in 30 min,feathering might keep the engine running until the bowl refills. Just a thought.
Try loosening your fuel cap and see if that changes anything,I'm wondering if you have a bad check in the fuel pump,combined with vacuum in the tank might empty the carb in 30 min,feathering might keep the engine running until the bowl refills. Just a thought.
Roger, that is possible. I never thought about less fuel and have not had a chance to see if any smoke is coming from the tailpipes upon start-up.
As usual, thank you for all your help!
Dan