head gasket or sheared key or ?

[38racing]

duaghter's neighbour. 28n7p7 . said it would quit. his brother works for JD but 2 tries and not fixed. I was set to tow it but figured I'd try it. started right up ran great so I drove it to daughter's. after doing the head gasket on her's I started his again. started right up .ran for 30 seconds and stopped. I did loosen fuel cap. no restart. maybe a backfire. I removed air cleaner. fuel in the intake. seems like output pumping from the intake. I didn't have spark tester with me and quit before pulling plug. next trip (hour away) I will change plug and verify spark. he claims brother checked flywheel key but I will check. IIRC he may have replaced coil. I will check gap. lastly going to take a head gasket. his mover is 97. daughter's was 04. and any thing else I should check?

[KE4AVB]

If fuel was in the air cleaner side of the intake I would suspect a leaky carburetor on top of other things. Either a needle valve or if a Nikki carburetor even a fuel gasket set.

As to what might be the problem just got through all the normal checks while it is in its failure mode.

[Luffydog]

Fuel shut solenoid maybe getting hot and failing as well

[38racing]

Fuel shut solenoid maybe getting hot and failing as well

It clicks when putting key to on but that doesn't rule it out. For that I usually replace it with just a bolt.

[38racing]

If fuel was in the air cleaner side of the intake I would suspect a leaky carburetor on top of other things. Either a needle valve or if a Nikki carburetor even a fuel gasket set.

As to what might be the problem just got through all the normal checks while it is in its failure mode.

I thought of the flooding but it ran for so long moving it and then I closed valve (IIRC) lol. Of course on 2nd try I didn't drive it to consume more fuel. I did turn off valve and couldn't get it to start. Maybe should leave sit and dry up, valve closed. and see if it will at least start. Then open valve just a tad and see how long it runs and with air filter off so I can see if it starts to flood.

[38racing]

went to pick it up yesterday. same thing. started right up. ran short 30 seconds and quit. backfire like some do when run out of fuel. ABS does click. I noticed it has jd pleated fuel filter. his is mtd gravity feed.back home yesterday still on truck. I checked flow at carb connection. full flow.
so then I attached inline spark tester. at first a spark then disappeared. attached tester to ground . great spark. in case it was ignition switch or seat safety (glance shows it disabled) I disconnected from coil at it's chassis connector. then I put sparkplug wire back on plug. cranked and got a major backfire. even puff of smoke. I quit at that point. had to go elsewhere. thinking after I realized when that I did that last crank the lead to the ABS was also disconnected. despite owner's claim of good flywheel key and new coil I going to check that. and put a ne sparkplug in it.

[bgsengine]

went to pick it up yesterday. same thing. started right up. ran short 30 seconds and quit. backfire like some do when run out of fuel. ABS does click. I noticed it has jd pleated fuel filter. his is mtd gravity feed.back home yesterday still on truck. I checked flow at carb connection. full flow.
so then I attached inline spark tester. at first a spark then disappeared. attached tester to ground . great spark. in case it was ignition switch or seat safety (glance shows it disabled) I disconnected from coil at it's chassis connector. then I put sparkplug wire back on plug. cranked and got a major backfire. even puff of smoke. I quit at that point. had to go elsewhere. thinking after I realized when that I did that last crank the lead to the ABS was also disconnected. despite owner's claim of good flywheel key and new coil I going to check that. and put a ne sparkplug in it.

Sounds to me like you got a bad spark plug

[38racing]

went to pick it up yesterday. same thing. started right up. ran short 30 seconds and quit. backfire like some do when run out of fuel. ABS does click. I noticed it has jd pleated fuel filter. his is mtd gravity feed.back home yesterday still on truck. I checked flow at carb connection. full flow.
so then I attached inline spark tester. at first a spark then disappeared. attached tester to ground . great spark. in case it was ignition switch or seat safety (glance shows it disabled) I disconnected from coil at it's chassis connector. then I put sparkplug wire back on plug. cranked and got a major backfire. even puff of smoke. I quit at that point. had to go elsewhere. thinking after I realized when that I did that last crank the lead to the ABS was also disconnected. despite owner's claim of good flywheel key and new coil I going to check that. and put a ne sparkplug in it.

Sounds to me like you got a bad spark plug

i was about to change it but had to leave. going to try that before unloading from truck too

[38racing]

So I put another plug in. With tester in line I had spark. Didn't start right away so removed tester. Then it started right up. I drove up and down driveway several times. Then parked and left running. At about the 5 minute mark from initial start it just shuts down like I had turned key off. I put the spark tester back in and maybe one spark and then none. I'm going to pull the shroud and remove the kill wire from the coil and replace with a lead that I can run out if I need to shut it down. First question will it spark? Seems to after sitting. So heat/running is causing coil failure or somewhere the kill wire is getting grounded.

[38racing]

So I pulled the shroud to do kill wire. I did notice something but first my story. I get it all back together and start it. I'm at the side near my kill wire. It starts but runs like crap. Won't come up to speed. Couple tries same thing. So for no valid reason I think I'll put his plug back in since it looked new . Same results. Like I said I was at the side and reaching over for the throttle. All the way up to start and then pull back a bit. EXCEPT this unit has separate pull choke which was out and I wasn't pushing back in. Did that and it ran great for 15 minutes until I shut it down to go to supper. Just about to try it again today. So what did I notice? The guy said flywheel key had been checked and I thought he said it was a new coil. No new coil on a unit stored inside would have that much rust on it. What I noted was I couldn't get my feeler gauge in gap on leading leg, just trailing lag. I had to remove coil to get my lead on so regapped to .012. My guess that metal expanded with heat and flwheel magnet actually rubbed the coil leg causing spark failure. If I get another long run with my kill lead then I test again with regular kill wire on.