GT275 Stalls out after hot and only runs with choke closed

[Ob1kubota]

My John Deere neighbor loves this tractor and since he's 91 years young I feel compelled to take care of him because his family is worthless when it comes to tractors. Enough said why Ob1 is into this job. I absolutely know nothing about this 17 HP Kaw engine but have some theories as to why this is happening. I suspect his Son-in-law has ran the engine hood into a gye wire for a utility tower in his back pasture and cracked the hing for the hood on the right side. When I pulled the hood up to get to the engine I noticed the seal for the flywheel housing ( this is an air cooled engine) has extreme wear on the side the hing is busted. Now here's the punch line... I think there is a relationship here with engine cooling capacity and the way the vacuum is supplied to the fuel pump. Before I spend time I really don't have to spare to help this old POOR guy does any body have any experience with what I suspect that there is some relationship with cooling the engine and the vacuum supply hose to the fuel pump? I have already pulled and flushed the tank, tank vent, fuel lines and installed a new JD OEM fuel filter. I have a new AM109212 pump but I feel if I just change it out the mower will return after hot with the same symptoms. Has anybody with GT275 ownership experienced this problem and what was the true fix. I have already had a couple JD buddies tell me to install an electric fuel pump but I think the tractor will continue to overheat any way and destroy this old codger's toy.

[ToadHill]

When engines of any kind only run with the choke closed it usually means that the engine is running lean. In my experience it is usually caused by air being sucked in after the carb jets, IE a leak around the gasket between the carb and the manifold.

[shot_gun]

Have you taken the shrouds off to see if there is any material packed in and around the cooling fins? We get this alot around here especialy if there is a little oil leak. The grass likes to sticks to it.

[crashz]

Well OB1, what Toad said makes sense. If it will only run with the choke, I think iits fuel related. A lean mixture will also cause your overheating on an air-cooled engine. Fix the fuel related issue and you'll probably see that it doesn't over-heat. Not sure what kind of carb is on that, but the smallest problem (like a stuck float) can cause a major issue.

PM on any aircooled engine is to routinely take the shrounds off and clean the cooling fins and air passage ways. I try to do this at least once a year with my push mower and weedwacker.

[Ken Cunningham]

It has been my experience that an engine that will only run with choke has a clogged carb. If I were working on it I would take the carb apart and clean out the passages with a small diameter wire.

Let us know what it turns out to be.

[Ob1kubota]

crashz

"PM on any aircooled engine is to routinely take the shrounds off and clean the cooling fins and air passage ways. I try to do this at least once a year with my push mower and weedwacker."

He's never done this in nine years he's had it. He sets his deck on 2 1/2 and mows six inch high grass and expects it to run 4 mph. I could go on but I won't...

Alright I'm going in the crankcase vacuum passage to the lift pump hose and run at 3350 or so rpm and check pull with a gauge. If that ain't at Kaw's spec I'll tear into the blower housing and clean the fans and update the flywheel screen for the FC540V engine. Next???????

[Ob1kubota]

Follow up to repairs: got a hold of TM1582 and proceeded with diagonostics. R&R blower housing, screen and fuel pump since its bolted to housing. Pulled plug and got 151 lbs of compression, good? book says no anything over 100 lbs means automatic compression release (ACR) is out of adjustment. This explains why the old guy was breaking starter bell housings (2) in the last two seasons. Now you say how is this related to the symptom of the problem... simple, if the valve timing is wrong at wide open throttle you can develop vapor lock on these small air cooled engines particularly if the tank vent is plugged with debris which I blew the valve open on the first repair. Here's the fix... adjust valve clearance cold at TDC cold at .006. put a dial indicator on the exhaust rocker adjustment set screw and nut. Slowly turn the nut on the top of the flywheel clockwise at TDC and make sure the exhaust valve moves .010 with the Intake valve fully seated ( the intake rocker will be loose on the retainer shaft as this happens) This determines that the ACR is set to specification. While inside the valve cover check the breather valve assembly. Retainer clearance is okay between .040 -.080. Check the reed valve for damage, wear distortion and replace if issues. If valves are in adjustment with correct compression the lower end or vacuum to the fuel pump should be correct so I didn't waste time doing a crankcase vacuum test. After torqueing all fastners to specs and reinstalling all the engine covers I went after the hood damage. These hoods are the most flemsey pieces of plastic Ivseen on a Deere product. I had to manufacture sheet metal hinges for both sides of the pivot pins and drill the end of frame so I could put a threaded dow rod through both rail to support and align the hood for function and ease of maintenance. After several hoursready for the test and testit he did at 2 inch height in six inch grass with complete success. It was all worth it to see that old man smile. Lord I hope to see 91 and owning a X749 with some young stud working on it for me!

[Nuru]

Ob1, definitely a good deed and you probably will have that wish carried out at 115 or 125 yrs young as with the advances in medicine over the next few decades, I am sure life expectancy will jump. Playin softball and baskeball at 80, hmmm, and not getting hurt.

[Ob1kubota]

Thanks Nuru.... nice name and I hope your right but the way the economy is going right now we will all out live our income retirements. I lost 6,000 in my 401K last quarter alone. I don't like any of the runners for the hot seat and war looks like the middle east is toast. The next 3 to 4 years will change humanity forever.