Groundsmaster 52 runs 10 minutes, then dies

[Volvoman]

Tractor is a Toro Groundsmaster 52 with 16HP Briggs L head cast iron engine, 32000 series. Manufactured back in 1980. The problem is, it runs and cuts fine for approximately ten minutes, then dies. I can interrupt the dying by choking the engine and it comes back to life. But, only for a few seconds. Then it dies again. Choking again before it totally shuts down and it comes back to life. This is a rinse and repeat thing until I limp back to the garage with it. Let it sit for an hour or longer, and it starts up, runs fine and cuts grass for another ten minutes. Then the cycle repeats. Does this sound like a coil going bad? Or, due to the fact I can choke it back to running before it completely dies, is it a fuel issue?

I have replaced the fuel filter, cleaned the carburetor, replaced the fuel lines, replaced the fuel pump, and with no change from doing that, have pulled the fuel tank and cleaned it out as well. Still no change. Oh yeah, I replaced the condenser for good measure.

I was of the understanding that a faulty coil would shut the engine down once it was hot, but then would not restart at all until the engine was totally cooled down. Or, will a failing coil cause the engine to die, but allow it to come back to life by quickly choking it as described above? I am leaving the coil replacement as a last resort due to it requiring the entire engine to be pulled from the tractor in order to access it. The ten minutes having to elapse before the problem arises leads me to think it is a heat related issue, most likely the coil. Anybody here had a similar problem with a cast iron horizontal shaft briggs?

Vvm

 

[seville009]

I'm going to suggest what I have seen many others suggest in similar seemingly fuel starved situations - maybe the fuel cap is defective. The next time it starts stalling, remove the fuel cap and see what happens. Hopefully it's that simple.

 

[Xfaxman]

Right the fuel cap may have a vent that is plugged.

If the fuel tank is like the 300 series, the tank will have a vent hose. And that might be plugged.

 

[MossRoad]

If you have to choke it to keep it running, that cuts the air and makes the mixture richer with fuel. Since cutting the air supply makes it run better, that would suggest not enough fuel in the mixture when the choke is off.

Make sense?

That would indicate a fuel starvation problem, as others suggest.

Some causes:
Fuel tank not venting.
Fuel filter restricted.
Fuel lines partially blocked.
Vapor lock.
Fuel pump getting hot.

But you’ve already done most of that.

Simplest test would be next time it hints at acting up, turn off the blades, set the parking brake, and crack the fuel cap open.

 

[Volvoman]

Sorry, I failed to mention that I have already loosened the gas cap to relieve any vacuum condition that may exist. Also, tried 3 different caps without any favorable results. Any thoughts on how a malfunctioning coil would behave?

 

[Volvoman]

Although I have drained the fuel tank twice, the fuel that I put back in was E10 regular. I am assuming there is no water in it, but to double check that, I’ll drain it one more time, then replace with non-oxygenated regular 91 octane, the recommended modern fuel for old engines. It’s a long shot maybe, but other than the coil, I cannot think of any other possible sources of this problem…

 

[Volvoman]

Some new information to add. Wife took the mower out this afternoon to try it again. She reported that after about ten minutes, while mowing, it suddenly did the shut down thing again. She stopped forward movement, while leaving the blades engaged, and found the engine gradually regained full rpm. She moved forward with deck engaged and cutting. A few feet later, same thing. She tried this repeatedly with the same result, but soon became impatient and drove back to the garage and parked it. The difference between what I found a day earlier is she didn’t have to choke it to regain rpms. So, this seems to me to reinforce the notion that this might be a fuel quality issue, or at least a fuel quantity issue. Or, possibly a combination of the two.

If the non-oxygenated fuel doesn’t make for further improvement tomorrow, will be taking the carb off one more time to see if 1) there may be water showing up in the bowl, or 2) if some crud has found it’s way into the carb and messing up the needle valve, or possibly some crud may have gotten into the brass elbow connecting the rubber fuel line to the carb. While a slim chance this has happened to the GM 52, I had exactly this problem a very long time ago in an old Studebaker, when a small pebble, just small enough to find it’s way into the fuel line and lodged in an elbow mounted to the fuel pump. Strange, but true. The chances of something like that happening here is remote to say the least.

 

[Xfaxman]

I have replaced the fuel filter,

Is it clear plastic so you can see the gas?

Any thoughts on how a malfunctioning coil would behave?

Pulling the choke would have no effect.

 

[M59]

I am agreeing with all others that this is a fuel starvation issue and not a faulty coil issue since you can keep the engine limping along by richening up the mix by adding choke. If a faulty coil then richening the mix would not allow engine to continue to run.

Do you have access to the float bowl? I would install a fuel shut off valve in the fuel line to the carb. The next time the engine dies, immediately close the valve and then remove the float bowl. I expect you will find it empty or nearly empty and at least so low the fuel is below the point it can be drawn into the engine.

I believe you have a rubber line that may be collapsing when it gets hot or you are pulling a vacuum in the full tank due to a defective one way valve that lets air into the fuel tank and is not functioning. Some engines use a hose to let air into the fuel tank and a bee or something else crawled in there or made a nest in the hose. Mud dauber?

Also the possibility of vapor lock which creates low fuel in the float bowl.

Installing the fuel shut off valve allows you to verify the low fuel/ no fuel problem so the float bowl doesn't refill before you can examine it.

 

[stuckmotor]

I too, think it's a fuel issue, possibly: wrong filter, filter installed backward, or collapsing fuel line. Just in case though, I'd probably get an inline spark checker handy and check for spark as soon as the engine quits running next time. My spark checker came from Harbor Freight and I love it. They're $3.99 and $4.99.

 

[seville009]

It's probably not a fuel quality issue, since you've already drained it twice. I had a truck that had an ethanol issue, but the engine didn't just slowly lose power but rather bucked and ran really rough. Ethanol treatment and then using non-ethanol gas fixed the issue.

 

[CobyRupert]

An air (leak), at the carb/intake manifold can also looks like a fuel starvation issue where choking the carb brings the air/fuel mix back into the right balance.
In those cases, yes, it’s lacking gas, but only because it’s sucking too much air. Maybe…

Seem like I’ve seen plastic intakes get a hairline crack that worsens as it warms up and leans motor out.

 

[Volvoman]

I am agreeing with all others that this is a fuel starvation issue and not a faulty coil issue since you can keep the engine limping along by richening up the mix by adding choke. If a faulty coil then richening the mix would not allow engine to continue to run.

Do you have access to the float bowl? I would install a fuel shut off valve in the fuel line to the carb. The next time the engine dies, immediately close the valve and then remove the float bowl. I expect you will find it empty or nearly empty and at least so low the fuel is below the point it can be drawn into the engine.

I believe you have a rubber line that may be collapsing when it gets hot or you are pulling a vacuum in the full tank due to a defective one way valve that lets air into the fuel tank and is not functioning. Some engines use a hose to let air into the fuel tank and a bee or something else crawled in there or made a nest in the hose. Mud dauber?

The lines were all replaced with new, with the exception of the rubber hose which exits the tank near the top and ends open to the atmosphere beneath the tractor, the purpose of which I assumed to be an overflow or for internal pressure relief. Would it not serve the same purpose as a vented cap? If so, is this a built-in redundancy? Perhaps I am not understanding the purpose for both.

Also the possibility of vapor lock which creates low fuel in the float bowl.

Installing the fuel shut off valve allows you to verify the low fuel/ no fuel problem so the float bowl doesn't refill before you can examine it.

I suspect this will be the case, too. Somewhere in the fuel delivery system, something is causing a blockage. Ruling out the hoses due to their being newly replaced, it leaves somewhere within/on the carburetor, or perhaps the vent hose. The fuel filter is new, and is the correct metal cannister stipulated in the Toro parts diagram. In/out ports are correctly located. Or….perhaps it may be some yet undetected water in the fuel that has is lingering somewhere in the fuel delivery system. When it is drawn into the carburetor and atomized, the engine stalls until incoming combustible gasoline displaces it. In theory anyway, that’s what I could envision as another possibility. Agree?

 

[jaxs]

I'm with the majority saying it's fuel starvation. Considering what you've done and it still doing it,I'd re-visit float/needle and seat assembly. To begin add 4 oz Seafoam to 32 oz gasoline (4oz in 1 quart). Once engine runs right,add 2 quarts gas and use mower as usual until it has been consumed. 1 oz in 1 gallon is the reccomended amount for daily use in the event you want to use remainder of Seafoam in can.
Ok back to float and needle assembly. Some of those old cast body Briggs carbs can have upper shell containing float removed with carb still mounted to engine. Carefully inspect needle and seat. If you can remove seat without damaging it,do so then use straw on spray carb cleaner and/or low pressure air to clear passage leading to seat. CAREFULLY use torch tip cleaner to remove undetectable varnish from seat passage making sure not to enlarge, scratch or damage. While in there,if high speed jet is easily accessible ,give it same treatment. I'll stop here in case you already have it apart on the bench but if this doesn't work,we can test coil without tearing engine down.

 

[setxjeff]

Mine did the exact thing. The plastic in-line quarter turn gas valve had swollen almost shut internally, probably from ethanol. There was a faint trickle thru the valve I replaced it with a 1/4 brass valve. No problems since.

 

[Volvoman]

I'm with the majority saying it's fuel starvation. Considering what you've done and it still doing it,I'd re-visit float/needle and seat assembly. To begin add 4 oz Seafoam to 32 oz gasoline (4oz in 1 quart). Once engine runs right,add 2 quarts gas and use mower as usual until it has been consumed. 1 oz in 1 gallon is the reccomended amount for daily use in the event you want to use remainder of Seafoam in can.
Ok back to float and needle assembly. Some of those old cast body Briggs carbs can have upper shell containing float removed with carb still mounted to engine. Carefully inspect needle and seat. If you can remove seat without damaging it,do so then use straw on spray carb cleaner and/or low pressure air to clear passage leading to seat. CAREFULLY use torch tip cleaner to remove undetectable varnish from seat passage making sure not to enlarge, scratch or damage. While in there,if high speed jet is easily accessible ,give it same treatment. I'll stop here in case you already have it apart on the bench but if this doesn't work,we can test coil without tearing engine down.

Have had the carb apart once and inspected the needle/seat at the time, then blew it out with an air jet. So, for any larger particles, pretty sure it is now free of any that may have been in it. But, as far as varnish is concerned, I didn’t spray any carb cleaner at the time, because I didn’t have any on hand at the time. But, will pick up a can tomorrow just in case. But, I have Seafoam on hand, and can add that to the newly added non-oxygenated gasoline. Will be doing some cutting this afternoon to see if the gas alone has improved the situation. If not, will be pulling the carb off again. As the engine is tucked into the Groundsmaster chassis with little room to spare, it’s a last resort item when removing the carb or the fuel pump. Not all that difficult, but tight quarters don’t leave much room for arms and hands to work in there. I am still suspicious of any water that may have contaminated the oxygenated fuel that was in the system prior to the problems starting. I drained the fuel into a red plastic two gallon gas can, so couldn’t see if any water was present. Had I drained it into a clean shallow pan, it would have been visible if present. By process of elimination, I’ll know the answer to that question this afternoon….

 

[jaxs]

If fuel is gravity fed AND carb bowl has a drain,can you let fuel drain for a several minutes and catch it so as not create a fire hazard? A continuous trickle would indicate no restriction. Continuous trickle from hose feeding carb but not from carb would narrow restriction down to carb. I believe you will find it's fuel starvation but before removing engine to change coil, buy one of these
You can watch spark and tell if it's skipping when engine falters. The little tool is a worthy addition for any tool box and is far better than pulling wires to test spark,not to mention it totally eliminates accidental shocks.

 

[M59]

The lines were all replaced with new, with the exception of the rubber hose which exits the tank near the top and ends open to the atmosphere beneath the tractor, the purpose of which I assumed to be an overflow or for internal pressure relief. Would it not serve the same purpose as a vented cap? If so, is this a built-in redundancy? Perhaps I am not understanding the purpose for both.

I suspect this will be the case, too. Somewhere in the fuel delivery system, something is causing a blockage. Ruling out the hoses due to their being newly replaced, it leaves somewhere within/on the carburetor, or perhaps the vent hose. The fuel filter is new, and is the correct metal cannister stipulated in the Toro parts diagram. In/out ports are correctly located. Or….perhaps it may be some yet undetected water in the fuel that has is lingering somewhere in the fuel delivery system. When it is drawn into the carburetor and atomized, the engine stalls until incoming combustible gasoline displaces it. In theory anyway, that’s what I could envision as another possibility. Agree?

Volvoman,

Based on your initial description of "I have replaced the fuel filter, cleaned the carburetor, replaced the fuel lines, replaced the fuel pump, and with no change from doing that, have pulled the fuel tank and cleaned it out as well. Still no change. Oh yeah, I replaced the condenser for good measure" it would appear you have done everything to eliminate a lack of quality fuel getting to the float bowl and eliminated water in fuel system. The fact that it runs for approx 10 minutes and then begins to stumble/ die and can be revived by closing the choke some points to incorrect fuel/ air mix ( lean ). I suspect the engine is running until float bowl is drawn down to point the fuel/air leans out and it stumbles.

I would go back to installing the fuel shut off in line, if possible, as near to carb as you can. That way you can shut the valve when it stumbles and verify gas level in float bowl at your leisure. If bowl is full or full enough float is closing inlet then fuel is NOT the problem. If fuel low then go back thru fuel delivery system again making no assumptions while doing so.

 

[Volvoman]

Well, some new information discovered this PM. As mentioned above, yesterday wife was out mowing and came back reporting it didn’t totally die as it would before. Considering this some improvement, I then switched out the E10 for some non-oxygenated fuel. Let stand overnight, then today went out to try mowing again. One more thing, I did add some Seafoam to the gasoline just before heading out to mow. So, here’s what the current state of affairs is: Initial startup went okay, had to briefly choke. Drove out to lawn area, all fine. Engaged mower deck and the engine began to immediately stumble, AND this time accompanied by a small cloud of blue smoke from the muffler. Never noticed that before, so maybe the seafoam? Nevertheless, I disengaged the mower deck and all smoothed out again fine. Tried re-engaging the deck and same stumbling and small blue cloud. Rinse and repeat several times with same results. So, drove back to the garage and did some adjusting on main jet. Made the adjustments by “feel and sound” method, observing a small blue cloud while rapidly opening and closing the main throttle repeatedly at the carb. And, was unable to adjust it so when engaging the deck that it would do so without smoking and stumbling. Not sure if something blocking the fuel pump pulse line where it leaves the engine block would contribute to this or not. Or, conversely, if oil is being sucked from the engine through the pulse line to the fuel pump, then to the carb when the engine calls for fuel.

The fuel tank is not feeding the carb by gravity at this time. Only a couple of quarts of fuel are in the tank, so fuel level is below the carb. Engine is fed gasoline by fuel pump.

Next move will be to go back into the carb, pull everything apart once more, clean and dry again, then reassemble. First time, I did not replace any parts. This time, may install a kit as well.

 

[MossRoad]

I recall when I discovered that my fuel pump was going out, when the tractor started running roughly, the level in the tank was below the level of the carb. If I fill the tank, the machine ran fine until the tank dropped down to that level again. Anyhow, sounds like you’ve tried that already.