Carb problem
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Joined: Aug 2019
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Carb problem
I just acquired a 1978 F600 with a 361 industrial motor. The carb was rebuilt and runs great. However, when you start the engine it coughs and sputters. You cannot take off or the engine will die. But, if
you let it warm up it runs like new.
The choke, governor, etc. have all been checked and appear properly adjusted but something is very wrong.
Free pizza to whoever figures this out.
Thanks.
ken
you let it warm up it runs like new.
The choke, governor, etc. have all been checked and appear properly adjusted but something is very wrong.
Free pizza to whoever figures this out.
Thanks.
ken
Laughing Gas
Joined: Nov 2013
Posts: 1,207
Likes: 60
From: S.E. Louisiana;so far USA
If everything is great after it warms up, I'll second the comment that it is likely something with the choke. I could never get my automatic choke to work correctly; hence, I converted to a manual choke & throttle.
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Thanks.
Post Fiend
Joined: Apr 2002
Posts: 19,311
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From: Waterloo, Iowa
Make sure compression is good, and no vacuum leaks, and ignition timing is running at spec. A mechanic's vacuum gauge is the only way to fly for engine diagnostics and tuning. If engine won't pull 18" to 20" steady at idle, find out why. Carb calibration and tuning is basically impossible if there are any problems elsewhere, they are completely dependent on a strong engine manifold vacuum.
A carb choke doesn't really work the way people sometimes think, they don't block the air off so much as they increase the velocity of the air that does flow, and consequently extra fuel is "pulled" from the well for cold enrichment. Hardly any air flows through a carb at idle, it needs the manifold vacuum to atomize the fuel. So anything that buggers that up, incorrect ignition timing, late valve timing, vacuum leaks, will cause problems. "90 Per Cent of Carb Problems are Ignition Related".
A carb choke doesn't really work the way people sometimes think, they don't block the air off so much as they increase the velocity of the air that does flow, and consequently extra fuel is "pulled" from the well for cold enrichment. Hardly any air flows through a carb at idle, it needs the manifold vacuum to atomize the fuel. So anything that buggers that up, incorrect ignition timing, late valve timing, vacuum leaks, will cause problems. "90 Per Cent of Carb Problems are Ignition Related".
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I am very glad to have joined this forum. I feel much better about tackling this beast Saturday. Will let you know what the outcome is soon. Pizza for ALL!!
Thanks for the great advice.
Ken
Thanks for the great advice.
Ken
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Grumpy goat
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Please don't send pizza here! My butt is wide enough. Just get your truck fixed.
Cargo Master
Joined: Dec 2004
Posts: 3,362
Likes: 22
From: Florence, SC
I just acquired a 1978 F600 with a 361 industrial motor. The carb was rebuilt and runs great. However, when you start the engine it coughs and sputters. You cannot take off or the engine will die. But, if
you let it warm up it runs like new.
The choke, governor, etc. have all been checked and appear properly adjusted but something is very wrong.
Free pizza to whoever figures this out.
Thanks.
ken
you let it warm up it runs like new.
The choke, governor, etc. have all been checked and appear properly adjusted but something is very wrong.
Free pizza to whoever figures this out.
Thanks.
ken
What is your starting procedure? If driven daily, your truck should only require *one* pump to start a cold engine. A warm engine wouldn't even need that. You should never have to "pump" the gas to start the engine.
The next time your engine is cold. pump the gas once. Then, remove the air cleaner lid and verify that the choke plate is completely closed. If it isn't, it's not set correctly.
If that checks out, start the engine, but do not pump the gas pedal. It should fire off immediately. When the engine starts, the choke plate should crack open just a little and the engine RPM should be higher than normal. If it doesn't do that, something isn't set correctly.
As the engine warms up, the choke plate should gradually open. At full operating temperature, the choke plate should be completely open.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
I just acquired a 1978 F600 with a 361 industrial 
motor. The carb was rebuilt and runs great.
However, when you start the engine it coughs and sputters. You cannot take off or the engine will die. But, if you let it warm up it runs like new.
The choke, governor, etc. have all been checked and appear properly adjusted but something is very wrong.
motor. The carb was rebuilt and runs great.However, when you start the engine it coughs and sputters. You cannot take off or the engine will die. But, if you let it warm up it runs like new.
The choke, governor, etc. have all been checked and appear properly adjusted but something is very wrong.
The 361 is not an industrial engine, per se...it's an FT engine. It was an option for 1964/78 500 and larger series trucks.
FT's also available 1964/78: 330 2V Medium Duty, 330 2V Heavy Duty, 391 4V
btw: In pic, 389 is a detuned for smog 391.
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