Ford 3600 gas Governor problem?

[SA Eldridge]

Appreciate everyone's input... Recently bought a 1978 Ford 3600 gas. It popped/backfired some when rapidly moving throttle, but bought it reasonably. Put a new Zenith carb on it and adjusted throttle linkage to appx. 650 low and 2250 high. Did not adjust carb. It now starts well, seems to run OK not under load and no longer pops/backfires when quickly moving throttle back and forth.

Problem... Put a 6' bush hog on it (raised 10"+ in appx. 20" tall grass) and it pops/backfires some when engaging PTO on bare ground and will pop/backfire/die for some reason while mowing at 2100RPM+. Pulling choke to make it more rich did not keep it from dying, so do not think it is lean. Since it seems to run well not under load, I do not think it is a fuel flow or plugs/points/distributor or timing issue. Seems like a Governor problem? I tried the test where you put on brake, apply 1/2 throttle and try to move Governor for more RPMS and it did not fight me. So, does this mean the Governor is bad? I also tried the test where you disconnect the Governor linkage and watch what governor does in response to throttle. Well, my tractor rev'd 3000+ until I manually grabbed the gov and throttled it down! Was not expecting that, but was not sure what to expect since I am not an expert on old gas tractors. Kinda hard to watch gov in relation to throttle. Will retest when my wife gets home. Thoughts? Thanks! SA

 

[used red MN]

Hello SA Eldridge, welcome to YT! I coming out with a left hook right at the bell! You said “I don’t think it is a fuel flow or plugs/points/distributor or timing issue.” There is a huge difference between thinking and knowing something is not the problem. Have you checked fuel flow or the points and plug and timing? First, I would try opening the main jet a 1/2 turn and if it repeats another 1/2 turn. If it still has trouble turn the jet back in that turn and look at the things above. All a governor does is monitor the engine speed to match where you have the throttle set, and then opens the throttle plate more if the engine speed lowers and closes it when the speed raises higher. It has zero ability to cause pops and backfires.

 

[SA Eldridge]

Hello SA Eldridge, welcome to YT! I coming out with a left hook right at the bell! You said “I don’t think it is a fuel flow or plugs/points/distributor or timing issue.” There is a huge difference between thinking and knowing something is not the problem. Have you checked fuel flow or the points and plug and timing? First, I would try opening the main jet a 1/2 turn and if it repeats another 1/2 turn. If it still has trouble turn the jet back in that turn and look at the things above. All a governor does is monitor the engine speed to match where you have the throttle set, and then opens the throttle plate more if the engine speed lowers and closes it when the speed raises higher. It has zero ability to cause pops and backfires.

Thanks! Just learned something about governors ;!) Will try adjusting the main jet. If I get what you are saying, sometimes it is starved for fuel and pops/dies (lean)? Kinda odd since RPM and grass height/density doesn't change before it pops/dies... Supposedly, it has new plugs/points/plugs last year, but who knows... Guess I need to check that too!

 

[leroy in ne]

Suggest checking fuel flow to the carb. Disconnect fuel line, I'm thinking most here say 1 pint in 2 minutes for minimum.

 

[SA Eldridge]

Suggest checking fuel flow to the carb. Disconnect fuel line, I'm thinking most here say 1 pint in 2 minutes for minimum.

Thanks. Kinda weird since it runs pretty well most of the time under load, then just pops/dies for some reason... then is hard to restart. Have gas cap loosened just in case it is failing and vapor locking. Figured low fuel pressure/obstruction would create a more consistent problem? For instance, with old carb and new carb, can mow at 2100 RPM for 15min - 1hr+ before it pops/dies. Noticed it happens more when I am turning, but ground is flat so does not make sense to me...

 

[used red MN]

It sounds like you fuel flow is just barely enough. When you turn the front wheels it takes more power than going in a straight line, simple physics. Leroy doesn’t realize your tractor has a fuel pump. What he is suggesting applies to strictly gravity feed systems with no pump. You would need to check that flow at the line feeding the pump and that is only if the tank and fuel level is higher than the fuel pump. You have 2 filters/screens in the system if it is still stock. Number 10 in the tank and number 30 in the sediment bowl. See linked diagram. CNHI Ford 3600 parts catalog There may also be a fine screen in the fitting where the fuel line connects to the carb. The fitting has to be removed from the carb to see it. Keep it clean around that if you open it up. If you get crud in there and there is no screen it could mess up your new carb.

 

[SA Eldridge]

It sounds like you fuel flow is just barely enough. When you turn the front wheels it takes more power than going in a straight line, simple physics. Leroy doesn’t realize your tractor has a fuel pump. What he is suggesting applies to strictly gravity feed systems with no pump. You would need to check that flow at the line feeding the pump and that is only if the tank and fuel level is higher than the fuel pump. You have 2 filters/screens in the system if it is still stock. Number 10 in the tank and number 30 in the sediment bowl. See linked diagram. CNHI Ford 3600 parts catalog There may also be a fine screen in the fitting where the fuel line connects to the carb. The fitting has to be removed from the carb to see it. Keep it clean around that if you open it up. If you get crud in there and there is no screen it could mess up your new carb.

Thanks! Really appreciate your feedback. It has the OEM filter screens (clear) and I put a clear inline filter on it to see/verify fuel flow.

 

[used red MN]

If you think you can see the actual fuel flow though that filter your kidding yourself! You can see movement particularly due to it having a pulsing fuel pump but this really tells you nothing. Tell me you can see a measure of a pint of flow through there and I will call BS on you!

 

[SA Eldridge]

If you think you can see the actual fuel flow though that filter your kidding yourself! You can see movement particularly due to it having a pulsing fuel pump but this really tells you nothing. Tell me you can see a measure of a pint of flow through there and I will call BS on you!

Thanks. Will measure fuel flow. Parked tractor and ran at various RPMs (held throttle in place for few mins) while watching the Governor linkage. It is moving wildly for some reason and causing popping/dying. However, Governor moves to adjust (more fuel) AFTER engine starts to cut-out. So, my Governor may be good even though it fails the 'fight it' test I found on here. Guess I need to verify fuel flow, timing, points/plugs/wires... But if any of that is the root cause, not sure why it is not more consistent w/ and w/o load. Right now I am running some Berryman ChemTool thru gas and Seafoam thru oil it in case valves are sticky. It passes the 'paper on exhaust test'.... Like you can hold paper on exhaust for very long to check valves :!)... May need to do a compression test.

 

[used red MN]

Looks like I misinformed you, your original carb doesn’t have an adjustable main jet only ann idle mixture adjustment. Unless the replacement carb you got has one. In this link it would be in place of plug 10. CNHI Ford 3600 zenith carb Or does your tractor have the Holley carb. I am directing you off what I see on an iPhone on that parts diagram, click on 02 Fuel system to see the other carb option. Hope you still have your original carb. You need to look at the points, check their gap and pull the plugs and take a fairly close-up picture of the end that sticks in the head, the 4 together is fine.

 

[Mark-Ia]

Engine hunting through the gov. is the signs of a plugged carb.

 

[65Ford2000]

Thanks. Will measure fuel flow. Parked tractor and ran at various RPMs (held throttle in place for few mins) while watching the Governor linkage. It is moving wildly for some reason and causing popping/dying. However, Governor moves to adjust (more fuel) AFTER engine starts to cut-out. So, my Governor may be good even though it fails the 'fight it' test I found on here. Guess I need to verify fuel flow, timing, points/plugs/wires... But if any of that is the root cause, not sure why it is not more consistent w/ and w/o load. Right now I am running some Berryman ChemTool thru gas and Seafoam thru oil it in case valves are sticky. It passes the 'paper on exhaust test'.... Like you can hold paper on exhaust for very long to check valves :!)... May need to do a compression test.

Hello SA. I have a Ford 2000 I rebuilt the Carb 3 times then realized the fuel pump design is garbage, I put a Edel-brook electric fuel pump on and that problem no longer exists starts right up and runs great.