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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Joec123able on August 10, 2016, 07:47:53 pm

Title: Hard starts when warm, but not hot or cold
Post by: Joec123able on August 10, 2016, 07:47:53 pm

My truck will start just fine when totally cold or at operating temp, but it acts almost like after I drive it and let it sit for maybe 30 mins or an hour, that it's flooding itself, I'll have to crank for probably 5 seconds or more. It will puff out white smoke upon start that smells rich of gas. Anyone have a clue what could be the cause? 1973 Chevy k-20, 350, th350, 205 transfer case.

Title: Re: Hard starts when warm, but not hot or cold
Post by: zieg85 on August 10, 2016, 09:21:41 pm

first thing I would check is the choke position.  Sounds like it cools down some and your choke closes up. 

Title: Re: Hard starts when warm, but not hot or cold
Post by: Ludwig Von 88 on August 11, 2016, 06:05:40 am

Hi Joec, how did you fix it? I have the same problem.

Title: Re: Hard starts when warm, but not hot or cold
Post by: thefarmboy21 on August 11, 2016, 12:29:45 pm

When it's warm, try holding the pedal to the floor....mine is running too rich and I have to do this anytime it's not a cold start. If it's warmed up and I don't hold the pedal down, it'll crank until the battery dies. An old time hot rider said to mash the gas, so I did and fires up no problem.

Title: Re: Hard starts when warm, but not hot or cold
Post by: Ludwig Von 88 on August 11, 2016, 12:57:13 pm

Thanx thefarmboy.

Title: Re: Hard starts when warm, but not hot or cold
Post by: Joec123able on August 11, 2016, 03:32:35 pm

I've tryed holding the gas to the floor or half throttle, made no difference for me. I'm gonna take a look at the choke, that sounds like a good possibility.

Title: Re: Hard starts when warm, but not hot or cold
Post by: blazer74 on August 11, 2016, 06:08:27 pm

Holding the pedal to the floor to start indicates flooding after shutdown.

Float setting too high or saturated float.

Too high fuel pressure from pump in the lines after shut down expands with heat soak, pressure goes up and can overcome the needle and seat and flooding occurs. 

A lot of aftermarket pumps put out too much fuel pressure.   

Ethanol in the fuel makes all this worse.

The Gm manuals state when starting a warm engine hold the pedal half way and crank. And no I don't have the reference handy.

I generally just crank and touch the pedal a Bit to get a good start after a 10-15 minute stop.

Title: Re: Hard starts when warm, but not hot or cold
Post by: Joec123able on August 11, 2016, 08:40:53 pm

Yea my truck still has the original starting procedure on the sun visor. It says to hold the pedal halfway when starting hot, mine starts fine hot with no pedal just not after being hot and then sitting for an hour or so. Also, I never use fuel that contains alcohol ever. Whether I hold the pedal to the floor or not it takes just as long to start either way.

Title: Re: Hard starts when warm, but not hot or cold
Post by: jg1977c20 on August 16, 2016, 06:59:22 pm

you probably are using fuel with ethanol as it is in all gasoline now except some brands of 92/94 octane -

-check the choke especially if its an old divorced choke
- how long since last carb rebuild ?
- white smoke is water ,maybe you have a head gasket starting to go and is steaming up things, black smoke would indicate rich

- if ethanol is causing issues you can run something like sta-bil for ethanol gas