Groundsmaster 52 runs 10 minutes, then dies

[piper184]

Great post. However this only works if the pulse line does not have a loop that can cause oil to collect in the pulse line. The pulse line must NOT have a loop between the pump and the pulse port. In other words, the pulse line MUST be all down hill from the pump.

Correct. A loop really messes things up if fluid gets in it. In my case the pump is below the engine so it is possible for crankcase fumes (2 stroke) to condense in the line and flow to the pump. The weep hole at the bottom of the pump takes care of that and the fuel tank is below the pump so it has to earn it's keep! Also Rotax (aircraft engine) says NO Ethanol, ever! Plus it likes 91 octane. Fortunately that is available.

I will second the comment about the condenser might be bad even though it is new. I have seen out of the box failures before. Same goes for fuel pumps. Ever open a box of nuts to fine one or more that don't have any threads inside? Stuff Happens...

 

[Volvoman]

Great post. However this only works if the pulse line does not have a loop that can cause oil to collect in the pulse line. The pulse line must NOT have a loop between the pump and the pulse port. In other words, the pulse line MUST be all down hill from the pump.

On the Groundsmaster 52, the pulse line is looped around the dipstick tube. This is how it is supposed to be positioned. Evidently the pulse vacuum is unaffected by any accumulation of oil in the loop.

 

[Tony H]

Looking at other downdraft carburetors, it appears that the Seat IS metal and it can be unscrewed out of the carb, when carb is disassembled. I'm still leaning toward a reduced diameter in a jet or Seat.
Was this a sudden issue or did it start after the machine sat for months? I don't remember if you mentioned the scenario.

 

[Volvoman]

Looking at other downdraft carburetors, it appears that the Seat IS metal and it can be unscrewed out of the carb, when carb is disassembled. I'm still leaning toward a reduced diameter in a jet or Seat.
Was this a sudden issue or did it start after the machine sat for months? I don't remember if you mentioned the scenario.

The problem arose suddenly. No advance warning. Unless the seat is pot metal gray, the usual brass screw-in seat wasn’t there. I looked specifically for it and wondered at the time I had it apart about why there wasn’t any. Well, it’s coming apart again in a few days when the kit arrives. Will post about it’s presence or absence when I’m in there. I can’t image it running well at all without a seat tho, as machining the carb body to simulate an insert seat would be difficult if not nearly impossible. The reduced diameter of a jet is very plausible. The kit contains a new high speed jet, so will see how it all pans out once back together.

 

[MossRoad]

The problem arose suddenly. No advance warning. Unless the seat is pot metal gray, the usual brass screw-in seat wasn’t there. I looked specifically for it and wondered at the time I had it apart about why there wasn’t any. Well, it’s coming apart again in a few days when the kit arrives. Will post about it’s presence or absence when I’m in there. I can’t image it running well at all without a seat tho, as machining the carb body to simulate an insert seat would be difficult if not nearly impossible. The reduced diameter of a jet is very plausible. The kit contains a new high speed jet, so will see how it all pans out once back together.

How much was the price of the kit VS a whole new carb? Just asking, because many moons ago I used to rebuild automobile carbs fairly often. However, with small engines these days, like chainsaws and weed eaters, a new carb is almost always just a couple bucks more than a rebuild kit.

I know your unit is older. But I was just curious.

 

[JBF43]

It isn't uncommon to have an engine run poorly,not start or intermittently run rough after a routine tune up,becasue new condenser is bad.

Have had this very thing happen in the past with auto tune-ups. Replaced points, plugs, and condenser just because it was time/ mileage. Engine ran on the old parts but wouldn't start after the tune-up. Put the old condenser back in and it cranked right up with the other new parts still in it. Just a possibility.

 

[Tony H]

The problem arose suddenly. No advance warning. Unless the seat is pot metal gray, the usual brass screw-in seat wasn’t there. I looked specifically for it and wondered at the time I had it apart about why there wasn’t any. Well, it’s coming apart again in a few days when the kit arrives. Will post about it’s presence or absence when I’m in there. I can’t image it running well at all without a seat tho, as machining the carb body to simulate an insert seat would be difficult if not nearly impossible. The reduced diameter of a jet is very plausible. The kit contains a new high speed jet, so will see how it all pans out once back together.

VERY curious what you find. Your issue is driving me crazy. You obviously know your way around an engine.
As you can tell from my posts, I'm leaning toward fuel. If it was ignition, I think it would be breaking up as you idled up, not just BOG down. Do you have Welding Tip cleaners that you can put thru the jets to see if something pushes out onto a paper towel?

 

[Volvoman]

How much was the price of the kit VS a whole new carb? Just asking, because many moons ago I used to rebuild automobile carbs fairly often. However, with small engines these days, like chainsaws and weed eaters, a new carb is almost always just a couple bucks more than a rebuild kit.

I know your unit is older. But I was just curious.

I paid $35 including postage for an OEM Briggs. I didn’t check on a new carb for it, as I have gone that route before for some much smaller engines and found the quality was unpredictable. Sometimes good, sometimes not. This carb is made to be rebuilt, so thought it best to go with the known high quality OEM Briggs parts. What I got had been on someone’s shelf for quite some time, no doubt, but it shouldn’t make any difference provided any rubber or vinyl parts are okay.

 

[MossRoad]

I paid $35 including postage for an OEM Briggs. I didn’t check on a new carb for it, as I have gone that route before for some much smaller engines and found the quality was unpredictable. Sometimes good, sometimes not. This carb is made to be rebuilt, so thought it best to go with the known high quality OEM Briggs parts. What I got had been on someone’s shelf for quite some time, no doubt, but it shouldn’t make any difference provided any rubber or vinyl parts are okay.

Thanks!

 

[Richard001]

On the Groundsmaster 52, the pulse line is looped around the dipstick tube. This is how it is supposed to be positioned. Evidently the pulse vacuum is unaffected by any accumulation of oil in the loop.

And you know this how ?

Have you checked the pulse line to see if there is oil in it ?

 

[Volvoman]

And you know this how ?

Have you checked the pulse line to see if there is oil in it ?

This is written in the original service manual for Groundsmaster 52. There wasn’t oil in the pulse line before putting on the new fuel pump, but I didn’t observe any smoking before the new fuel pump was installed either. Will check it again, as the new replacement fuel pump is purported to have significantly more pumping ability than the original. The original is a toro part #27-7000 IIRC, allegedly made by Walbro as their model 3000. The new Walbro 3000, sold as the replacement for the old one, is totally different in appearance and composition. While the old one is metal and a flat rectangular shape, the new one is round and made of a black manmade material, supposedly not plastic. I hadn’t made the connection that perhaps the new fuel pump may be an added player in this. The old fuel pump 27-7000 is no longer manufactured. I did notice an online source for one, but priced over $150, so I passed in favor of the new version at $30. The sales rep who sold the new one swore the new one was a superior pump…..

 

[laurencen]

this summer on a Mule with impulse pump that went bad, it worked but next to no pressure, would keep machine running but when used it ran out of fuel, the replacement pump was bad out the box so just because you replace does not guarantee its good

since then I have replaced all impulse when questionable with electric pumps

the original pump was aluminum square dealer said not available, the replacement was a round plastic at 60 dollars, this plastic one was bad out the box.

just for giggles look in the Walmart.com site, they have impulse pumps and funy enough they have both the square and round versions, if I recall the square was in the 20 dollar range and the round under 20, took a few weeks to arrive but worth looking

 

[Volvoman]

This is the fuel pump used in Groundsmaster 52 to feed the cast iron Briggs 16hp single.

 

[M59]

Volvoman,
This youtube video may be useful: "How to diagnose an impulse fuel pump".
Also interesting is the fuel pump is on a Toro Proline 120. Looks real similar to the Groundmaster.

 

[jaxs]

Volvoman,
This youtube video may be useful: "How to diagnose an impulse fuel pump".
Also interesting is the fuel pump is on a Toro Proline 120. Looks real similar to the Groundmaster.

Do you think post #58 from 4 days ago is unclear?

 

[M59]

Do you think post #58 from 4 days ago is unclear?

No nothing unclear about post #58.
The contributor's posts keep floating around the fuel pump and testing the fuel delivery to the carb.
The youtube video was directly addressing Volvoman's specific issue of initial posting. I felt Volvoman would benefit.

 

[Volvoman]

Thanks M59, for posting this. This is a great way to rule the fuel pump “in” or “out” as the problem. A big time saver!

 

[M59]

Thanks M59, for posting this. This is a great way to rule the fuel pump “in” or “out” as the problem. A big time saver!

Your welcome.
Jaxs had the explanation correct for debugging but once I saw this video, I figured you should see it since both Toros are essentially the same machine and the problem appears to replicate your symptoms.

 

[Volvoman]

Yes, Jaxs absolutely did as well. I hadn‘t overlooked his recommendation, having put a bookmark on it to refer back once the system is ready to put back into place. The carb remains the first suspect, with fuel pump and lines second. Carb kit should be on the doorstep tomorrow, put into the carb by Tuesday and back into the GM 52 by days end, provided no other yet undiscovered issues come to light. Thanks once again to everyone who has contributed so many suggestions. Will post the results by late Tuesday/early Wednesday.

 

[hanie cole]

What was the solution, Volvoman?