Groundsmaster 52 runs 10 minutes, then dies

[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.