sputtering on cold starts

mike561 · #1 06-16-2010, 11:43 AM

Just had my carb rebuilt and now every morning when i go to start up, after a few seconds the engine starts to sputter and tries to stall, i had to rev it hard to keep it from stalling. if i let it stall it will start back up, warm up and run just fine. any ideas??? i got the 4bbl q-jet btw.

inafogg · #2 06-16-2010, 12:14 PM

could be the choke setting.if you paid for the rebuild have them take a look
at it when its cold.

mike561 · #3 06-16-2010, 02:38 PM

yeah i think it might be the choke but didnt want to go messing around with it since these electronic q jets are really touchy. I'll be takin it back over there though just was hoping it was something i could do real quick and easy

Blt2Lst · #4 06-16-2010, 04:06 PM

Quote:

Originally Posted by mike561

electronic q jets are really touchy.

Not really..

If you are unfamiliar with your carb, have someone check the choke when the car is cold. It probably needs an adjustment which is not hard to do. The carb shop probably got it close during the rebuild. Take the car back to them, they should be able to help you get it adjusted properly. Even though the carb has some electronics in it, the choke assembly is still manually operated.
You may just need to raise the fast idle if the choke is adjusted properly.

I just had to play with mine a little after my carb rebuild.

I,m sure someone will chime in on how to adjust it properly.

j cAT · #5 06-16-2010, 06:26 PM

Quote:

Originally Posted by mike561

Just had my carb rebuilt and now every morning when i go to start up, after a few seconds the engine starts to sputter and tries to stall, i had to rev it hard to keep it from stalling. if i let it stall it will start back up, warm up and run just fine. any ideas??? i got the 4bbl q-jet btw.

first thing is to make sure that the choke linkages are clean and work smoothly..some times they rust up get gummed up..then with a vacuum gauge make sure those choke pull off devices have no leaks ...

don't adjust anything until it is checked out first..

It could be that now with the warmer weather your electric choke stove needs replacing as the spring over time will loose its ability to close the choke plate fully on a cold start ..If the choke plate does not close this causes hard cold start...

I hope they replaced the choke when they did the rebuild ...that is the one item that does fail ...as well as those pull off vacuum operated plungers..

mike561 · #6 06-17-2010, 10:51 AM

I know the pull off was replaced a few months ago. it does already seem to idle fast on cold start ups, maybe even too fast because it deiseled alot yesterday when i shut it off. I left it at the shop though overnight so i will see what they have to say, before the rebuild it started and ran just fine on cold startups.

mike561 · #7 06-17-2010, 05:13 PM

I got a tip that if its still idling fast before it warms up completely to shut off the engine while its still in drive then put it in park to keep it from deiseling

Blt2Lst · #8 06-17-2010, 07:13 PM

Quote:

Originally Posted by mike561

I got a tip that if its still idling fast before it warms up completely to shut off the engine while its still in drive then put it in park to keep it from deiseling

That does work but you should still try to correct the problem..

mike561 · #9 06-18-2010, 11:57 AM

ok well it seems to be good now, i geuss the choke was opening too far if i remember correctly.

j cAT · #10 06-18-2010, 03:03 PM

Quote:

Originally Posted by mike561

ok well it seems to be good now, i geuss the choke was opening too far if i remember correctly.

I use a drill bit of .170 inch for the choke plate opening adjustment ...then adjust the screw 1/4 turn in either direction to get it perfect...

on the high speed idle you have a step cut cam that changes the cold start idle . at the highest cam rpm adjust to 1700 RPM...

on the engine run on on shut down with the idle too high on these engines this is well known ...back in the early 80's this leaving in gear on engine shut down was the norm ...then the gas formula changed and this was not a problem ..I suspect your engine is running to rich ..

timing could be off ...too much carbon in the combustion chambers , perhaps the carb was leaking fuel into the engine from the float not adjust/worn ...there is a product called regain this removes these deposits ..reduces the run on problem ...

because you have a carb , check for vacuum leaks at least every oil change..

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