Hard start after 90 minutes - Team Camaro Tech
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post #1 of 6 (permalink) Old Feb 19th, 17, 01:37 PM Thread Starter
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Morgan
 
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Hard start after 90 minutes

Stock zl1 alluminum motor, Holley 850 annular booster.

Cold I pum4296p the gas 4x, any less it does not fire up, no choke, so runs ruff for the first minute, then idles on its own. Now stop at the old neibohorhood and when I leave, I now pump it once, it fires and runs for 10-15 seconds and shuts off, then I must keep it to floor and crank until it fires like it is flooded. Get gas and it fires right up, no gas.air fuel meter is good, did not look at it after it fires and then shuts off. Mechanical fuel pump btw.

IDEAS:
Heat soak and bowls are nearly empty? I have a 1/4 insulted gasket on it

Do these alluminum motors need more gas when heat soaked? Should I put on the metal heat shield ?

The car runs perfect air fuel numbers and better than the stock 4296

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post #2 of 6 (permalink) Old Feb 19th, 17, 02:36 PM Thread Starter
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Morgan
 
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Re: Hard start after 90 minutes

I just went out to the garage 90 minutes after shutting it off, pulled off the squirter to verify I had the check valve, all good, went to the secondary and when I pulled the squirter I could see fuel boiling around the check valve.

I checked both float bowls and could not see fuel when I shook the car real good. I set them at barely coming out when I bump the car, so I believe I am boiling the fuel out of the bowls.

The question is float level too high? Needle and seats are fresh and the .120 ones at that? Check valve not seating? Losey fuel, I did put fresh gas in today, it is 62 in Detroit today?

Is winter gas worse for boiling over? Or better volitility?

Does the alluminum dissipate the heat that much faster than steal? These beer can motors are weird?

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post #3 of 6 (permalink) Old Feb 19th, 17, 03:12 PM
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Re: Hard start after 90 minutes

Not sure about a holley, but I had weird carb issues with my Qjet last year, and it turned out the residue from the ethanol fuel where gumming the jets up and causing the float to not work right. I suggest a good cleaning.

Kevin


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post #4 of 6 (permalink) Old Feb 19th, 17, 03:29 PM Thread Starter
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Re: Hard start after 90 minutes

Carb is fresh and clean.

I have been reading about the winter fuel our gas stations are using, they say to buy the lowest octane the car will. Run on, I use 93, so that and the winter blend may be part of it, not often it get 60 degrees in Detroit in February

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post #5 of 6 (permalink) Old Feb 19th, 17, 04:31 PM
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Re: Hard start after 90 minutes

Gas recipe has a lot to do with it. I think the problem may be the carb not having a choke for enriching the mixture when cold.
Another carb, with choke, regardless of size would probably give better results for cold starting.
Yes, fuel may be cooked out. Remove a bottom bowl screw and drain into a cup to see how much is left.
At cold start, you can fit a funnel into the bowl vents and fill with gas to see if this would help starting.
If starts better, then yes, fuel peculating from heat.
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post #6 of 6 (permalink) Old Feb 19th, 17, 06:45 PM
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Re: Hard start after 90 minutes

Lots of good advice. IMHO I think if you can see it boiling off 90 minutes later the combination of winter blends and heat are catching up with you.


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