Takes a long time to start after sitting? - Team Camaro Tech
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post #1 of 27 (permalink) Old Nov 15th, 02, 05:49 AM Thread Starter
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If my car sits for a long time, I have to crank if alot before it finally starts. I'm running an Edelbrock carb and Holley mechanical fuel pump. If I start the car a day after it's been running, it fires right up.

What causes this? Is the fuel evaporating out of the carb? Can this be fixed?

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68 468 700R4, and here it is;
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post #2 of 27 (permalink) Old Nov 15th, 02, 08:40 AM
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Fuel is leaking down out of the carb,
After shutting it down when its hot pull the air cleaner, smell for raw gas etc,
Don't know about your brand of carb, but the Q-jets have a lead plug on the bottom that is prone to leaking over night.
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post #3 of 27 (permalink) Old Nov 15th, 02, 08:53 AM
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Mine does the same thing with a Holley DP.

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Rick Dorion
69 RS Conv,355,Autogear M22,4.10's and I don't worry about stone chips ( yet ).
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post #4 of 27 (permalink) Old Nov 15th, 02, 03:50 PM
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Both my Q-jet and Demon to that, but only if it sits for a week or longer. The Q-jets plugs have been epoxied too.

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1969 Base Camaro
Vortec 355, Perf. RPM, Demon Carb., TH-400
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[This message has been edited by Silver69Camaro (edited 11-15-2002).]
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post #5 of 27 (permalink) Old Nov 16th, 02, 07:07 AM
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I have the same trouble with my Holley 650 DP, its even worse if the weather is a bit on the cool side...I think I have to mess around with my choke more though.
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post #6 of 27 (permalink) Old Nov 16th, 02, 05:11 PM Thread Starter
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I'm running a brand new Edelbrock 800 carb. So I guess there really isn't anything to do to fix this?
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post #7 of 27 (permalink) Old Nov 16th, 02, 11:04 PM
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on my old 350 with a quadrajet did this, but when i put my 750 demon dp (no choke) on it it started perfect every time. and after i put my 406 in, its still the same, a quick single pump when cold and it starts right up, and just hit the key when its warm, no problem. i would think you should be able to achieve this w/ your car as well, with some fine tuning/adjusting.
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post #8 of 27 (permalink) Old Nov 17th, 02, 12:50 PM
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Basically the fuel is just draining out of your fuel bowls down the line and into the tank. Just gravity, unless its leaking out the carb onto or into your intake you have nothing to worry about.
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post #9 of 27 (permalink) Old Nov 17th, 02, 01:30 PM
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The fuel isn't likely to be siphoning back into the tank! It's leaking into the intake and down the cylinder walls into the pan. If you get enough fuel in the oil pan, you could blow the valve covers and the oil pan right off the motor. (seen this happen! Kewl! wasn't my car!) If you are lucky enough for this not to happen, you could dilute the oil enough to ruin the bearings and/or seize the oil pump. If this is a new carb and it's leaking, take it off and get another one under warranty! or get it fixed.
Jim
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post #10 of 27 (permalink) Old Nov 17th, 02, 05:16 PM
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Matt Jones
 
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I dunno 'bout that...my Demon does it, my Qjet does it, my old Edelbrock 1406 did it, and my new 625CFM Carter did it. I think the fuel is evaporating out of the fuel bowls, personally. But this is after an extended period of time though...not just a couple of days.

------------------
Matt Jones
1969 Base Camaro
Vortec 355, Perf. RPM, Demon Carb., TH-400
All sheetmetal is NOS GM
See my webpage at: http://www.geocities.com/compuboy007/
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post #11 of 27 (permalink) Old Nov 17th, 02, 05:51 PM
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If you look closely at the mechanics of a float/needle and seat set up. It's like a toilet tank. The fuel is sitting below the valve that allows fuel to flow into the bowl. There is no way for the fuel to get back up there. In a Holley or a Demon, it would have to siphon two tanks empty. Also, the fuel pump works like your heart. One way clapper valves prevent fuel from draining back on the pressure side of the pump. The only other possibility besides leaking would be percolation. There may be enough heat soak into the carb to boil the fuel out.
As mentioned in the earlier post, a Q jet has a problem with a lead bowel plug that can leak. But then again what does MarkM mean by "a long time". Your suggestion of fuel evaporation might be the case?
Jim
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post #12 of 27 (permalink) Old Nov 17th, 02, 05:57 PM
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Something's fishy, Mark. If I let my car sit for days, or a couple weeks, all I have to do is to pump the pedal once, and it fires on first try. Always. How's your timing? If you don't have enough advance at initial, it could crank a bit before catching spark.

If you think it is losing fuel, wait a couple days and then open the air cleaner, poke you head in there, and manually push the throttle plates. Look for gas out of the accelerator pump. If you get some, the issue is not fuel leakage/evap.
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post #13 of 27 (permalink) Old Nov 17th, 02, 08:11 PM
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i have seen problems like this fixed by putting in a fuel pump. perhaps the check valve goes bad or something, and allows the fuel to drain back.

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post #14 of 27 (permalink) Old Nov 18th, 02, 02:57 PM
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ihave a 1406 edlbrock also, AND a brand new fuel pump with a Mr Gasket glass in-line filter. you can actually watch the fuel level in the filter decrease over time. it IS draining out of the filter and fuel line back to the tank. absolutly! i have investigated this by disconnecting the line from the tank to the pump and putting a bowl under it. it happens, no big deal.
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post #15 of 27 (permalink) Old Nov 18th, 02, 04:23 PM
 
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hey mark,

got a novel idea. get fuel injection.....lol...

but i have to agree with the evaporation/or leak down... have had the same proble. i think that it may evaprorate a bit from the vent tubes....ever take off a carb turn it over to drain it and watch the fuel come from the vent tubes?

i agree with Mean and CAm... if you stab the throttle and see the gas pump from teh accelerator, then there is still fuel in the bowl....

good chance that the fuel is possibly draining back to the tank and you have to crank it to get it back to the bowls... you could get an electric fuel pump and see if the gas gets there sooner...

HTH, JS
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