Author Topic: hard starts 20+ mins after shutting off hot  (Read 12438 times)

Offline Joec123able

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hard starts 20+ mins after shutting off hot
« on: May 26, 2017, 06:14:36 PM »
1973 chevy k20. 350/350/205. My truck has a 1406 edelbrock carb electric choke. I bought the truck over a year ago and ever since it always starts instantly when cold. When I first bought it I would shut it off hot and try to start it right away and it would be difficult to start. I put a wood spacer on and it fixed the initial hard starting. But ever since then, I shut it off hot, it sits for about 20+ minutes and then I have to crank it multiple times before it eventually stumbles to a start but then runs fine after. It also puffs grey smoke out of the exhaust occasional too only upon start up then the smoke stops. It's an annoying problem I'm tired of dealing with. Anyone else ever fix the same problem?

Offline Irish_Alley

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Re: hard starts 20+ mins after shutting off hot
« Reply #1 on: May 26, 2017, 07:08:15 PM »
could be a few problems. one is a worn starter or one thats getting heat soaked or a bad connection. another issue is timing being too far advanced, this can cause a hard start issue when warm. or vapor lock, caused by fuel getting too hot and vaporizing in the like and preventing liquid fuel from reaching the carb. but that one is generally related to the engine being run really hard or hotter than normal days. if you have a timing light check your initial timing and for loose or bad connections at your starter and battery. i generally set initial timing 16° or less
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Offline VileZambonie

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Re: hard starts 20+ mins after shutting off hot
« Reply #2 on: May 26, 2017, 07:18:56 PM »
I think he's saying it's an extended crank to start when hot.

You need to check the choke operation first.
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Offline Irish_Alley

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Re: hard starts 20+ mins after shutting off hot
« Reply #3 on: May 26, 2017, 07:39:45 PM »
yes
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Offline Joec123able

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Re: hard starts 20+ mins after shutting off hot
« Reply #4 on: May 26, 2017, 07:42:32 PM »
Right, the starter is newer and cranks fine. I just have to crank it over multiple times before it starts. I thought about timing but I have never messed with timing and would have no clue what I'm doing lol. Also my choke works fine.

Offline Dr_Snooz

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Re: hard starts 20+ mins after shutting off hot
« Reply #5 on: May 26, 2017, 08:57:00 PM »
Probably still the same problem. The heat soaks into the carb and boils the fuel out of the bowl. An aftermarket carb spacer on mine fixed the problem.
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Offline Joec123able

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Re: hard starts 20+ mins after shutting off hot
« Reply #6 on: May 26, 2017, 10:28:12 PM »
Probably still the same problem. The heat soaks into the carb and boils the fuel out of the bowl. An aftermarket carb spacer on mine fixed the problem.

I already put one and like I said, it partially fixed it. Before I added that it was always hard to start hot, now its hard to start hot after it sits for about 20+ minutes and then it's hard to start until it's completely cooled again.

Offline blazer74

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Re: hard starts 20+ mins after shutting off hot
« Reply #7 on: May 26, 2017, 11:47:25 PM »
Another thought is fuel pressure. Too much fuel pressure and heat expansion in the lines after shut down can cause flooding by overcoming the needle/seat.
Ethanol in the fuel doesn't help either. Vapor locks, boil off and evaporates quicker.

Offline Irish_Alley

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Re: hard starts 20+ mins after shutting off hot
« Reply #8 on: May 27, 2017, 12:58:12 AM »
something else to think of is fuel dripping into the engine after shut off from the carb. this might flood the engine and what seams like a cool down time might just be the fuel evaporating
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Offline Joec123able

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Re: hard starts 20+ mins after shutting off hot
« Reply #9 on: May 27, 2017, 01:23:44 AM »
Another thought is fuel pressure. Too much fuel pressure and heat expansion in the lines after shut down can cause flooding by overcoming the needle/seat.
Ethanol in the fuel doesn't help either. Vapor locks, boil off and evaporates quicker.

something else to think of is fuel dripping into the engine after shut off from the carb. this might flood the engine and what seams like a cool down time might just be the fuel evaporating

So if that's the problem I should literally see fuel dropping into the intake after shut off? If that's the case I assume that means I need a new carb or a rebuild.
« Last Edit: May 27, 2017, 01:27:01 AM by Joec123able »

Offline Irish_Alley

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Re: hard starts 20+ mins after shutting off hot
« Reply #10 on: May 27, 2017, 01:45:41 AM »
you might be able to hear it also. take the air filter off so it doesnt muffle the sound
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Offline Jerr-conn

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Re: hard starts 20+ mins after shutting off hot
« Reply #11 on: May 27, 2017, 05:54:27 AM »
Sounds like you need a valve job. Check compression when hot.
Jerry

Offline VileZambonie

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Re: hard starts 20+ mins after shutting off hot
« Reply #12 on: May 27, 2017, 07:58:46 AM »
Get it hot so the condition occurs and shut the engine off. Let it sit for the 20 minutes, remove the air cleaner and verify the choke is fully open. Looking down through the air horn actuate the throttle and verify fuel is discharged from the accelerator pump nozzles.

How is your distributor advance connected, ported or manifold vacuum? What is the base timing set at?
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Offline Joec123able

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Re: hard starts 20+ mins after shutting off hot
« Reply #13 on: May 27, 2017, 11:19:51 AM »
Get it so the condition occurs and shut the engine off. Let it sit for the 20 minutes, remove the air cleaner and verify the choke is fully open. Looking down through the air horn actuate the throttle and verify fuel is discharged from the accelerator pump nozzles.

How is your distributor advance connected, ported or manifold vacuum? What is the base timing set at?

My vacuum advanced isn't even hooked up. The port for it is plugged on the carb. idk what the timing is set at or how to check.

Offline SkinnyG

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Re: hard starts 20+ mins after shutting off hot
« Reply #14 on: May 27, 2017, 11:41:55 AM »
My C10 ~always~ and I mean ~always~ needs to be cranked WOT for a hot re-start.  And I've gone through the entire fuel and ignition system thoroughly.  The more volatile fuels of today boil inside the carb, flooding the engine.  Crank wide open throttle (flood-clear), and it will fire after a bit.
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