Loping 4000 4 cyclinder tractor

Blueford4000 · Jun 18, 2018

Two problems. At idle engine dies. At fast idle engine lopes.

Engine starts cold with no choke....if you choke it, engine floods.
This is not a problem, just describing it.

I suspect carb problem as these symtoms point to a lean mixture. Is there a way to rule out manifold leak as cause of lean mixture, or is that not even worth pursuing.

Any help is appreciated.

souNdguy · Jun 19, 2018

start her up cold, spray some start fluid around the carb and manifold. Only do this cold.. you don't want a home-made flame
thrower.

If the rpm's change you have a vacuum leak.

You can also try enriching the main needle a hair and see what it does.

lastly.. the gov spring isn't pre-tensioned is it?

Blueford4000 · Jun 19, 2018

I will try spraying some ether, like you said, carefully.

Where on the carb is the main needle adj screw?

Thanks.

Blueford4000 · Jun 19, 2018

Also, where is the governor spring located.

Thanks.

Keith Williams · Jun 19, 2018

Blueford4000,
You can find most of the info you are looking for in the owner's manual.
I uploaded mine to the "other" site for N tractors. (we are not allowed to link to it from here).
Keith

Dollar Bill · Jun 20, 2018

Engine starts cold with no choke....if you choke it, engine floods.

Fords are generally cold-blooded. Starting without choking and loping indicate a fat (too rich) mixture.

I differentiate loping and surging as two different symptoms.
Loping = Cammed up muscle car
Surging = RPM methodically alternate between low and fast idle

Blueford4000 · Jun 20, 2018

Thanks Bill.
It is surging.....not loping.

RobCons · Jun 20, 2018

My new to me 4 cylinder 4000 was doing the same thing. Look for a lean mixture, adequate gas flow through carb, float adjustment, throttle/governor linkage adjustment, or faulty governor. I was able to adjust my float and linkage to eliminate the surging but the governor would not operate. Replaced governor and all seems well.

Blueford4000 · Jun 20, 2018

Thanks....I found an online manual and it shows me where the adj screws are, along with dierctions to adjust. As well as the governor. I learned a lot from the manual. Thanks again.

Blueford4000 · Jun 20, 2018

Bill,
Are surging and loping both caused by a lean mixture?
Thanks.

sotxbill · Jun 20, 2018

too rich can cause it to surge... then when it is loaded, it leans out. so the main jet setting is a bit of a anomaly as you set it a bit on the rich side so that when you put the engine under heavy load, and the governor opens up the butterfly, your mixture will be correct. But remove the heavy load, and the mixture will go back to slightly rich again.

If you could stand beside the tractor while its under heavy load and set the main jet, that would be the perfect situation. (ie with a pto dyno) But most cant so its a bit of trial and error, but bottom line with no load, the engine will "roll" back and forth a bit as its a bit rich.

As others said, starting cold with no choke... it usually a sign of a rich idle setting, or a very high float setting.

However most of the time, carb problems are from stopped up jets, due to external_link gas gluing the ports closed or making the float sticky.

Dollar Bill · Jun 20, 2018

A fat mixture will cause loping where a lean mix contributes to surging.

souNdguy · Jun 21, 2018

on a MS carb, it's the big down pointing needle.

as for the governor. follow the hand throttle linkage to the governor, then the governor rod to the butterfly on the carb.

showcrop · Jun 21, 2018

Your owner's manual will tell you that it is supposed to have a "rolling" idle. I would not call that surging or loping, but you should expect to constantly go up and down by 70-100 RPMs.

Loping 4000 4 cyclinder tractor

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