Ford 8n starts but dies without choke

[fatl844]

My ford 8n I just got it about a month ago and it would start but struggled to get going and strugged up hills. It was leaking at the glass bowl so I replaced it, and replaced the fuel line at the same time, kept the elbow, the little filter in the elbow the guy at the shop said looked ok. Fixed the leak in the glass bowl. The guy I bought it from changed it to 12v and replaced the spark plugs and the carborator. But it seems to me like the issue is fuel, not sure how or why as I replaced all of the fuel line except that little elbow? Does anybody know what make this carborator is so I can figure out what the settings are supposed to be? Could it be a throttle issue?

 

[old]

My ford 8n I just got it about a month ago and it would start but struggled to get going and strugged up hills. It was leaking at the glass bowl so I replaced it, and replaced the fuel line at the same time, kept the elbow, the little filter in the elbow the guy at the shop said looked ok. Fixed the leak in the glass bowl. The guy I bought it from changed it to 12v and replaced the spark plugs and the carborator. But it seems to me like the issue is fuel, not sure how or why as I replaced all of the fuel line except that little elbow? Does anybody know what make this carborator is so I can figure out what the settings are supposed to be? Could it be a throttle issue?

Looks like a M/S clone. Top idle screw should be set to 1.5 turns from bottom and main jet the one pointing down at a 45 degree angle set to 2 turn out from bottom then fine tune with it running. Also check that you have a good flow of gas from the carb drain plug. You should get enough to fill a pint jar from the drain plug on the bottom of the carb to fill a pint jar in less then 2 minutes. If you don't have that type of flow you have a problem in the tank or lines of sediment bowl

 

[Eman85]

Do the timed fuel flow test first at the plug on the bottom of the carb. When you say you replaced the glass bowl did you just replace the glass? the gasket? or the whole fuel shutoff?

 

[Jim in LA]

My ford 8n I just got it about a month ago and it would start but struggled to get going and strugged up hills. It was leaking at the glass bowl so I replaced it, and replaced the fuel line at the same time, kept the elbow, the little filter in the elbow the guy at the shop said looked ok. Fixed the leak in the glass bowl. The guy I bought it from changed it to 12v and replaced the spark plugs and the carborator. But it seems to me like the issue is fuel, not sure how or why as I replaced all of the fuel line except that little elbow? Does anybody know what make this carborator is so I can figure out what the settings are supposed to be? Could it be a throttle issue?

There’s three filters on your tractor 1. Top of fuel valve assembly
2. In the top of the glass fuel bowl casting(flat
round screen).
3. Carb fuel inlet elbow
Any of these could be missing or clogged. The modern elbow screens are not near as sturdy as they used to be and I think they are shorter than the originals.

 

[fatl844]

Do the timed fuel flow test first at the plug on the bottom of the carb. When you say you replaced the glass bowl did you just replace the glass? the gasket? or the whole fuel shutoff?

The whole fuel shutoff

 

[fatl844]

There’s three filters on your tractor 1. Top of fuel valve assembly
2. In the top of the glass fuel bowl casting(flat
round screen).
3. Carb fuel inlet elbow
Any of these could be missing or clogged. The modern elbow screens are not near as sturdy as they used to be and I think they are shorter than the originals.

I replaced the whole fuel shutoff so that is two of the screens. The guy at the auto parts place said the filter at that elbow is ok, but I wonder if I took that out and see what happened and then replace it if that's the problem

 

[old]

I replaced the whole fuel shutoff so that is two of the screens. The guy at the auto parts place said the filter at that elbow is ok, but I wonder if I took that out and see what happened and then replace it if that's the problem

Again the flow test is simple and easy and the first place to start. Why is it so many new people seem to not understand a simple test that is tried and true and a person like me has used it hundreds of times if not thousands of time

 

[used red MN]

Hello ..844, welcome to YT! The M/S that was thrown out is Marvel Schebler the brand all Ford “N” series used. It was called a “clone” because the carb you have is an overseas produced “copy cat” carburetor. Some of them work fine while others can just never be made to run right. Not saying yours is one of those just throwing out the possibility. Completing the timed fuel test as directed out of the carb bowl drain plug ensures if the blame can be placed on the carburetor by ruling out inadequate fuel supply. Catching the fuel for the timed test should begin 5 seconds after the drain plug is removed so you are not measuring the fuel that is in the reserve of the carb fuel bowl. The screen in the elbow should stay in place, it is your best defense against debris that can cause problems with the sealing of the float needle valve and passing debris into the carb that can plug jetting passages.

 

[John P.]

I had a similar problem years ago. The original tank was rusting internally and chunks of rust were clogging the inlet inside the tank to the sediment bowl. Do the flow test above.

 

[fatl844]

Looks like a M/S clone. Top idle screw should be set to 1.5 turns from bottom and main jet the one pointing down at a 45 degree angle set to 2 turn out from bottom then fine tune with it running. Also check that you have a good flow of gas from the carb drain plug. You should get enough to fill a pint jar from the drain plug on the bottom of the carb to fill a pint jar in less then 2 minutes. If you don't have that type of flow you have a problem in the tank or lines of sediment bowl

Ok I reset the carb like you said here. I did the fuel flow test, I did a measuring glass instead of pint bc that's all I had, and 2 cups is a pint. It went to the 1.4, then I took off the elbow and took out that little filter and retested, 1.6. Then I refilled the Gass tank full, fiddled with the glass bowl a little bit but it says 2 full turns, and tested again and got 1.5 in two minutes. So it is a fuel issue right? I don't know what else to do for that though. I already replaced the whole fuel shutoff and glass bowl part, replaced the fuel line, not sure what else I can replace to get full flow, it looks like it is flowing good into the glass bowl, it's always full. Something to do with air? I went ahead and took off the bottom of the air assemble and cleaned it out it was pretty gunked up in there, could that be it? I could take the whole thing off and soak that mesh in there in diesel or something?

 

[used red MN]

Ok I reset the carb like you said here. I did the fuel flow test, I did a measuring glass instead of pint bc that's all I had, and 2 cups is a pint. It went to the 1.4, then I took off the elbow and took out that little filter and retested, 1.6. Then I refilled the Gass tank full, fiddled with the glass bowl a little bit but it says 2 full turns, and tested again and got 1.5 in two minutes. So it is a fuel issue right? I don't know what else to do for that though. I already replaced the whole fuel shutoff and glass bowl part, replaced the fuel line, not sure what else I can replace to get full flow, it looks like it is flowing good into the glass bowl, it's always full. Something to do with air? I went ahead and took off the bottom of the air assemble and cleaned it out it was pretty gunked up in there, could that be it? I could take the whole thing off and soak that mesh in there in diesel or something?

Here’s the deal, the specs given to you were a shot gun blast approach. They have given you a test bench mark higher than your tractor actually requires. Under tests an 8N used 2.5 gph (under the heaviest belt load 2.7 gph) by calculations a pint in 3 minutes is 2.5 gallons per hour. The tractor itself going up an incline generally will not load the engine to the point of where it will require the fuel it is capable of using under a full constant load. If I am thinking about this right your 1.5 cups equals a 3/4 pint. You are timing it two minutes. So if you repeated that for an hour you would catch a 3/4 pint 30 times. Calculating that .75 x 30=22.5 pints divide by 8 pints in a gallon you get 2.8 gph enough to support your tractors highest fuel use. How does the tractor perform now? When you quickly pull the throttle open down does it sputter and stumble then rev up? If so turn the front main jet knob out a 1/2 turn see if it is better. If not quite to the point it picks up speed without a stumble try adding another half turn. Do that 3 times until you have turned it out an additional 1 and 1/2 turns. Now drive it around again and see how it is acting. Is running up the hills better? If not keep in mind what I said about “clone” carbs in my other reply, not condemning your carb it may just needed cleaned and some tweaking. Your question in this post is about your carb, but the ignition also comes into play. The condition of the points, is the wiring for the 12v conversion correct, are the plug wires good, is the timing right?? all these things need considered.

 

[fatl844]

I had a similar problem years ago. The original tank was rusting internally and chunks of rust were clogging the inlet inside the tank to the sediment bowl. Do the flow test above.

Would changing the whole glass bowl shutoff assembly not fix this problem? Is there something else inside the tank that I need to do? When I took off the shutoff it seems flow freely out of the tank

 

[used red MN]

Would changing the whole glass bowl shutoff assembly not fix this problem? Is there something else inside the tank that I need to do? When I took off the shutoff it seems flow freely out of the tank

The posted times aren’t showing up yet but you must have wrote this about replacing the fuel shut off before you read my reply #11.

 

[Eman85]

When you did the fuel flow test another thing to try is taking the fuel cap off. No air in, no fuel out. it sounds like you have enough flow. If it needs choke to stay running it's got a fuel problem most likely in carburetor. Either simple adjustment or a poorly made carburetor. Do you have the old carburetor?

 

[fatl844]

When you did the fuel flow test another thing to try is taking the fuel cap off. No air in, no fuel out. it sounds like you have enough flow. If it needs choke to stay running it's got a fuel problem most likely in carburetor. Either simple adjustment or a poorly made carburetor. Do you have the old carburetor?

It has another adjustment screw on the back I didn't mess with that one at all

 

[used red MN]

It has another adjustment screw on the back I didn't mess with that one at all

I assume the screw you are talking about is in the moving lever attached to the throttle shaft. All that screw does is set the idle speed by adjusting how far the throttle plate is held open. If you can’t get the engine to respond correctly by adjusting the one at the front that sets at an angle with the big head there is another problem that needs addressed. Refer to my reply 11 and Eman’s reply 14.

 

[Smalltowner]

My ford 8n I just got it about a month ago and it would start but struggled to get going and strugged up hills. It was leaking at the glass bowl so I replaced it, and replaced the fuel line at the same time, kept the elbow, the little filter in the elbow the guy at the shop said looked ok. Fixed the leak in the glass bowl. The guy I bought it from changed it to 12v and replaced the spark plugs and the carborator. But it seems to me like the issue is fuel, not sure how or why as I replaced all of the fuel line except that little elbow? Does anybody know what make this carborator is so I can figure out what the settings are supposed to be? Could it be a throttle issue?

One thing nobody mentioned is the fuel bowl gasket on carb. Usually the leak is on engine side of carb. Replacing gasket also allows you to clean inside of bowl and inspect float while it’s off.

 

[Jim L WA]

Hi fati844, welcome to our world. In your original post you said, It seems to me that the issue is fuel...... But having to use the choke to keep it running can also be due to a weak spark. So you need to check for that. Take an old spark plug if you have one, and set the gap to 1/4 inch. Connect it to one of you spark plug wires and lay it against the top on the engine and while cranking the engine with the key on, see if a spark will jump that gap. If you don't have an old plug, just temporarily open the gap on one of your plugs.
If you want, you can go to an auto parts store and buy an adjustable spark tester and set that to 1/4 inch.
Let us know the results.

 

[fatl844]

Here’s the deal, the specs given to you were a shot gun blast approach. They have given you a test bench mark higher than your tractor actually requires. Under tests an 8N used 2.5 gph (under the heaviest belt load 2.7 gph) by calculations a pint in 3 minutes is 2.5 gallons per hour. The tractor itself going up an incline generally will not load the engine to the point of where it will require the fuel it is capable of using under a full constant load. If I am thinking about this right your 1.5 cups equals a 3/4 pint. You are timing it two minutes. So if you repeated that for an hour you would catch a 3/4 pint 30 times. Calculating that .75 x 30=22.5 pints divide by 8 pints in a gallon you get 2.8 gph enough to support your tractors highest fuel use. How does the tractor perform now? When you quickly pull the throttle open down does it sputter and stumble then rev up? If so turn the front main jet knob out a 1/2 turn see if it is better. If not quite to the point it picks up speed without a stumble try adding another half turn. Do that 3 times until you have turned it out an additional 1 and 1/2 turns. Now drive it around again and see how it is acting. Is running up the hills better? If not keep in mind what I said about “clone” carbs in my other reply, not condemning your carb it may just needed cleaned and some tweaking. Your question in this post is about your carb, but the ignition also comes into play. The condition of the points, is the wiring for the 12v conversion correct, are the plug wires good, is the timing right?? all these things need considered.

It won't idle now, I think im going to try and replace the spark plugs

 

[fatl844]

When you did the fuel flow test another thing to try is taking the fuel cap off. No air in, no fuel out. it sounds like you have enough flow. If it needs choke to stay running it's got a fuel problem most likely in carburetor. Either simple adjustment or a poorly made carburetor. Do you have the old carburetor?

No I don't have it, the guy I bought it from had replaced it recently, along with the plugs and wires, and the solenoid.