john deere 4020

joseywales · Apr 13, 2014

trouble with carb on a gas tractor anyone have any luck with a after market rebuilt one wheres the best place?

tim s · Apr 13, 2014

It"s unlikely that you will ever get it to run right,,it"s the nature of those with gas engines, they run great once they lean into the load on full throttle, but as they build up to it they flutter a bit...almost like you need to pull the choke a little to help it along....one of the reasons a lot of them get switched to diesels...

joseywales · Apr 13, 2014

that does seem about rite. it doesn't get used much and I'm having a hard time getting it running just thought a new carb mite help doesn't seem much to the carb though i guess ill try and clean it. is changing it to diesel a hard job?

Mike M · Apr 13, 2014

What carb. do you have ? The cast iron zenith or the alum box marvel schebler.
The zenith is the only on worth putting any money into.

Seems like I'm the only one around that can make a 4020 gas run right and like the gas engine !
I purposly sought one out back in the early 1990's gave it a through going over fixing all the neglected items and it has been 100% reliable ever since. Only items i have done since were a starter and fuel transfer pump. These were not replaced on the first going over.
For a loader tractor,winter use,lots of short run lift and move loader operations and still have some big HP when needed it is hard to beat the 4020 gas.

LP GAS ONLY · Apr 13, 2014

Had a buddy with a 3010 and he bought 300 gal of gas at a time. He had trouble also. We drained the gas from the tractor tank and put in 5gal. of premium gas. It ran like a new tractor. if you don't use it much just put enough gas in for what you are doing. gas now days goes bad in about 3 months. Try that and see if it don't help you.

Mike M · Apr 13, 2014

Couldn't go back and add in first post ?

As far as buying reman units I try not to. It's usually better to repair one that you know where it came from.
Like he old saying goes if you want something done right do it yourself.

FFF · Apr 13, 2014

I have a 2510 gas, it runs great, starts right up no skipping and hesitating. Surely a 4020 gas didn"t skip and not run great when they left the factory. I think these gas tractors get a bad reputation.

joseywales · Apr 13, 2014

this tractors been used on the family farm over30 years we rent out the farm now just use it for a little mowing and whatnot always ran pretty good maybe bad gas is the fuel lift pump the fuel pump i guess replaced that yesterday wasn't getting fuel to carb I'm going to clean it did replace the accelerator pump in carb couples years ago it is the bendix carb thanks for the help

tim s · Apr 13, 2014

I was working on a 3020 gas years ago at the farmers place,, he decided to put a "new" carb on it, about $500,,it didn't change a thing...just passing this along before you waste a lot of money...clean fuel is always a must, and there are a lot of different qualities of fuel out there now. As for changing to a diesel, it will cost you about $4,000, you should consider trading to a diesel, if you decide to switch yours over we can help you with it...

tim s · Apr 13, 2014

I have been around them since the early 70's, when we had a 3020 gas for a while,,no I don't think that they ever ran good....

joseywales · Apr 13, 2014

thanks for the help probably wonldnt do that just wondered

buickanddeere · Apr 13, 2014

It's often caused by some failed or mis-adjusted component. That looks good and/or shouldn't make any difference but does.
Would not be the first time a cam was installed wrong.A phantom intake manifold leak? Wrong timing or wrong mixture for the most obscure reasons.
Anybody ever check the valve lash and valve spring pressure?

Nate JD · Apr 13, 2014

While your checking make sure your ignition is working 100% right. You may want to consider a pointless system.

David G · Apr 13, 2014

Tim S,

We should partner up on a fuel injection conversion for the new gen gas.

joseywales · Apr 13, 2014

where do you find out about that

Mike M · Apr 13, 2014

I'll still take mine old school ! Just like the 1981 F350 I have.
Carb. Kit $30.00 fuel pump less then that and took a whole lot less time to replace then the newer fuel injected machines.

tim s · Apr 13, 2014

I have given it some thought....

David G · Apr 13, 2014

I would be more than willing to work with you on it. I know the pitfalls, probably ALL of them. My difficulty is in not having a dyno.

David G · Apr 13, 2014

Pointless ignition comes with the fuel injection for FREE.

wilson ind · Apr 13, 2014

a little off the wall but worked for me on pony motor on 720 &730 andcat pony motor. Get about 5 gal of aviation gasoline. do not mix- put in basicly empty tank. Just try it will tell if fuel is problem . if it helps consider best possible standard fuel possible . Not always avation gasoline. That would be too expensive. Had friend ready to overhaul pony engine on D7. He buys 2 gal of avation gasoline , never has had to overhaul the pony engine. My D7U older tractor,use avation in pony. Makes life easier!!

wilson ind · Apr 13, 2014

In hindsight Deere maybe should have went all diesel at introduction of 4 and 6 cy larger tractors.

tim s · Apr 13, 2014

Yes that would have been my vote, they quit building gasoline engines in 1974 I think...

NEIADan · Apr 13, 2014

Don't hesitate re-checking that accelerator pump. That was a yearly thing when we ran a gas 3020. Another thing to check is the distributor shaft for looseness and gap in the points. We found years ago that those distributors wore and you lost full advance on the timing and the points were eratic because of the bouncing distributor shaft. Put in a new distributor and had a much smoother running tractor.

john deere 4020

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