Fuel or spark issue?

[Oliverguy-NE Ohio]

Hi all, my 77 has been a pain in my butt today. Went to mow some corn stalks and it started acting up. I starts, runs, then stalls. I have good fuel delivery and it has been running just fine. When it is running before it stalls it runs good but does seem to mis fire slightly which it never did. Recently I put and electronic ignition in it and it made it run better than it did and it already ran pretty good. I also put the new alternator on it today. I thought that was causing this issue somehow but it was charging the battery at 14.2 volts. So not over or under charging just perfect. I don't know if something is up with my electronic Ignition or what? Got any ideas?

 

[rustred]

You need to check for the problem as soon as it stalls. Is there fuel in the carb bowl by checking the drain ? Is there spark ?
A charging system has nothing to do with a running tractors performance , if the battery. Is charged of course.

 

[Oliverguy-NE Ohio]

You need to check for the problem as soon as it stalls. Is there fuel in the carb bowl by checking the drain ? Is there spark ?
A charging system has nothing to do with a running tractors performance , if the battery. Is charged of course

I will check right after it stalls. I was thinking originally that it was the alternator not charging or something but now after checking it has good charging voltage I don't have any reason to think that it is the alternator

 

[Tgrasher]

My bet is on the fuel getting restricted by something like a bug in the fuel tank or a piece of rust and then floating away when the engine dies. The other place is the cavity just under the needle valve where a piece of rust can block and then dislodge when fuel pushes it away. You may have to drain a pint of fuel out of the carburetor drain before it shows and plugs. The misfiring before it dies is a symptom of this.

 

[Oliverguy-NE Ohio]

My bet is on the fuel getting restricted by something like a bug in the fuel tank or a piece of rust and then floating away when the engine dies. The other place is the cavity just under the needle valve where a piece of rust can block and then dislodge when fuel pushes it away. You may have to drain a pint of fuel out of the carburetor drain before it shows and plugs. The misfiring before it dies is a symptom of this.

okay thanks!

 

[gblj]

Hi all, my 77 has been a pain in my butt today. Went to mow some corn stalks and it started acting up. I starts, runs, then stalls. I have good fuel delivery and it has been running just fine. When it is running before it stalls it runs good but does seem to mis fire slightly which it never did. Recently I put and electronic ignition in it and it made it run better than it did and it already ran pretty good. I also put the new alternator on it today. I thought that was causing this issue somehow but it was charging the battery at 14.2 volts. So not over or under charging just perfect. I don't know if something is up with my electronic Ignition or what? Got any ideas?

I had a stink bug in my 8n gas tank, it stalled out a couple of times.

 

[Oliverguy-NE Ohio]

My bet is on the fuel getting restricted by something like a bug in the fuel tank or a piece of rust and then floating away when the engine dies. The other place is the cavity just under the needle valve where a piece of rust can block and then dislodge when fuel pushes it away. You may have to drain a pint of fuel out of the carburetor drain before it shows and plugs. The misfiring before it dies is a symptom of this.

I was thinking and became curious how this would cause misfireing? Just wondering not doubting your knowledge, just curious?

 

[NoDakInMN]

I was thinking and became curious how this would cause misfireing? Just wondering not doubting your knowledge, just curious?

As fuel supply is restricted it leans out the supply to the cylinders causing misfires.

 

[used red MN]

I was thinking and became curious how this would cause misfireing? Just wondering not doubting your knowledge, just curious?

…Answer per NoDak. How did you check for adequate fuel flow? As mentioned above checking it at the carb bowl drain is the final word in my opinion. I don’t think Oliver utilized them but many brands have a screen in the inlet fitting of the carb that can plug. When you pull the carb drain plug you need to give it a 5 count and then see what the flow is. A trickle of fuel coming in the carb bowl replenishes it by the time you get the plug out and can lead to a false diagnosis. Also a sediment bowl glass that remains full is not an indicator that the carb is getting adequate fuel flow, many are fooled by this observation.

 

[rustred]

Very simple check is the flow check. Remove line from carb and then open sediment bowl valve , gas has to glow a full stream , which of course depends on your fuel in tank level. If it’s sputtering and lazily flowing you know the problem is from that line back to tank. That’s the way I always check fuel flows. That carb drain is handy for draining the carb to see how much trash comes out with the gas. I catch it in a clean soup can. Many times the sediment bowl inlet in the tank is the problem from rusty tanks. Then finally it’s just plugged solid. Depends if your tank is clean or dirty. ? So what did u find out ?

 

[Oliverguy-NE Ohio]

…Answer per NoDak. How did you check for adequate fuel flow? As mentioned above checking it at the carb bowl drain is the final word in my opinion. I don’t think Oliver utilized them but many brands have a screen in the inlet fitting of the carb that can plug. When you pull the carb drain plug you need to give it a 5 count and then see what the flow is. A trickle of fuel coming in the carb bowl replenishes it by the time you get the plug out and can lead to a false diagnosis. Also a sediment bowl glass that remains full is not an indicator that the carb is getting adequate fuel flow, many are fooled by this observation.

This is the way I checked. Let it drain for at least 15 seconds and flow was still fine

 

[Oliverguy-NE Ohio]

Very simple check is the flow check. Remove line from carb and then open sediment bowl valve , gas has to glow a full stream , which of course depends on your fuel in tank level. If it’s sputtering and lazily flowing you know the problem is from that line back to tank. That’s the way I always check fuel flows. That carb drain is handy for draining the carb to see how much trash comes out with the gas. I catch it in a clean soup can. Many times the sediment bowl inlet in the tank is the problem from rusty tanks. Then finally it’s just plugged solid. Depends if your tank is clean or dirty. ? So what did u find out ?

well the tank is clean. barely any rust and absolutely no flakes. Flow is fine from the carb but the inline filter is getting pretty dirty from a year of little bits of stuff getting in it.

 

[showcrop]

well the tank is clean. barely any rust and absolutely no flakes. Flow is fine from the carb but the inline filter is getting pretty dirty from a year of little bits of stuff getting in it.

The standard check for fuel to the carb, posted here many times over many years is from the carb drain for two minutes looking for 16 oz. in addition, you want to see your plugs wet after cranking for three seconds without starting.

 

[rrlund]

Just spit balling. Is it sucking air somewhere? I'm trying to figure why it would get worse when it runs a while though.

I remember Chris Losey or somebody telling about a 77 or 88 one time that was driving them crazy at the dealership. They finally figured out that it was vapor locking. They figured it out by laying a temporary fuel line outside, away from the engine heat. On that note, it doesn't have an inline filter does it? Those will vapor lock if they get hot sometimes.

Another thought. How much history do you know about this tractor? Is it the one you've had all along or was it in that group that you bought? The reason I ask, I'd read in one of the Oliver magazines about a 60 that a guy had replaced the manifold on and it wouldn't fun right after that. Turned out the replacement manifold was off a KD engine instead of a gas only and the venturi was a different diameter. Seems to me like the hole was smaller. The carb bolted up alright, but the difference was up inside a little ways.

 

[scootergmc]

Eliminate the intake as a problem first... remove it from the carb. Does the problem persist?

If yes, next I'd run the tractor around with a 100% clean (and vented) piggyback tank hooked directly to the carb, thereby eliminating the tractor's possibly dirty fuel system. Does the problem persist?

Let us know.

 

[cjunrau]

Hi all, my 77 has been a pain in my butt today. Went to mow some corn stalks and it started acting up. I starts, runs, then stalls. I have good fuel delivery and it has been running just fine. When it is running before it stalls it runs good but does seem to mis fire slightly which it never did. Recently I put and electronic ignition in it and it made it run better than it did and it already ran pretty good. I also put the new alternator on it today. I thought that was causing this issue somehow but it was charging the battery at 14.2 volts. So not over or under charging just perfect. I don't know if something is up with my electronic Ignition or what? Got any ideas?

When it wants to stall spray gas in the intake. That lets you know if it is gas related.
I have a 2 litre pop bottle with a small hole in the lid for that purpose

 

[Oliverguy-NE Ohio]

Just spit balling. Is it sucking air somewhere? I'm trying to figure why it would get worse when it runs a while though.

I remember Chris Losey or somebody telling about a 77 or 88 one time that was driving them crazy at the dealership. They finally figured out that it was vapor locking. They figured it out by laying a temporary fuel line outside, away from the engine heat. On that note, it doesn't have an inline filter does it? Those will vapor lock if they get hot sometimes.

Another thought. How much history do you know about this tractor? Is it the one you've had all along or was it in that group that you bought? The reason I ask, I'd read in one of the Oliver magazines about a 60 that a guy had replaced the manifold on and it wouldn't fun right after that. Turned out the replacement manifold was off a KD engine instead of a gas only and the venturi was a different diameter. Seems to me like the hole was smaller. The carb bolted up alright, but the difference was up inside a little ways.

well I don't know what happened before this but it it's been on the farm for 30 plus years. sat for 25 only been running for a year now. just happened the other day before that it was running perfectly. it does indeed have an inline filter ...

 

[Oliverguy-NE Ohio]

Eliminate the intake as a problem first... remove it from the carb. Does the problem persist?

If yes, next I'd run the tractor around with a 100% clean (and vented) piggyback tank hooked directly to the carb, thereby eliminating the tractor's possibly dirty fuel system. Does the problem persist?

Let us know.

will do but won't get to it till this weekend due to work

 

[rrlund]

well I don't know what happened before this but it it's been on the farm for 30 plus years. sat for 25 only been running for a year now. just happened the other day before that it was running perfectly. it does indeed have an inline filter ...

I'd take that filter out and splice the line back together. See if it does it then.

 

[ss55]

Hi all, my 77 has been a pain in my butt today. Went to mow some corn stalks and it started acting up. I starts, runs, then stalls. I have good fuel delivery and it has been running just fine. When it is running before it stalls it runs good but does seem to mis fire slightly which it never did. Recently I put and electronic ignition in it and it made it run better than it did and it already ran pretty good. I also put the new alternator on it today. I thought that was causing this issue somehow but it was charging the battery at 14.2 volts. So not over or under charging just perfect. I don't know if something is up with my electronic Ignition or what? Got any ideas?

If you think it could be starving for fuel (running lean) as it dies, try giving it some choke to see if it runs better with a richer fuel mix.