1650 dies when it heats up.

[Matt G.]

Originally Posted by save_old_iron

A clogged cap will cause a high vacuum to build in the fuel tank and will limit the delivery of fuel thru the fuel pump.

I have had success temporarily splicing a section of clear fuel line from the carb to the fuel filter to help visually identify lack of fuel to the fuel pump. A temporary section of clear line after the fuel pump can help identify failing valves / rubber diaphragm in the fuel pump assy.

There is no fuel pump in a 1650.

[teejk]

just a thought...what does your plug look like? I lost all my manuals in a move and relied on a Kohler manual that I found on-line...that showed .035 gap for the K341 but it would start acting goofy when hot (back-firing, eradic operation, etc.). The plug (Champion H10C) showed heavy carbon build-up.

Then somebody here was kind enough to post the Cub owner's manual. That showed .025 gap across all engines. With nothing to lose, I re-gapped and have to say that the dog doesn't hide under the bed when I start it now.

[dclinansmith]

In one of your posts you said something like it almost wants to backfire when it quits. When it does quit, shut the ignition switch off and stand quietly beside the engine. Listen for the SNAP of a valve cooling off and closing. It may not happen on the first try. It all depends on the position of the camshaft lobe. My 149 did that years ago and a steady diet of Marvel Mystery Oil has eliminated the problem. I recently had a 1650 with a similar problem, it turned out to be the coil. I put a new one on the problem was the same. Right now it is running great with a 42 year old coil from my chevy pickup.

[fleetlines]

I had a coil that worked fine till it heated up a little.

[save_old_iron]

Originally Posted by Matt G.

There is no fuel pump in a 1650.

for the clarification. That's just my Cub "noob(iness)" showing thru. It really surprises me a big block kohler in a CC doesn't have a fuel pump. In my previous experience with WH and some Sears tractors, even the 10HP engines typically have a pump.

Having said that, the recommendation for checking fuel system venting and potential for vapor lock are still valid, maybe even more so in a system without a fuel pump.

So I keep learning on my journey down the yellow brick road.

[_DX3_]

The need for a fuel pump on these cubs is determined by the location of the fuel tank. On the Quiet Lines back, the fuel tanks sit above the carb, therefore the gravity flow does not pose a problem for fuel delivery. On the 82 series they use a fuel pump due to about half of the fuel tank being below the level of the carb and this can cause a no flow issue if just using gravity as the fuel level in the tank lowers. Also obviously if a fuel tank is under the seat a pump is probably going to be required. I am like you, I am still learning stuff all the time too.

[makabart]

I replaced the coil with a blue bosch as suggested by others. I finally got it, put it in, started right up, mowed and almost got done with the yard, then it happened again. I'm glad I didn't throw the other coil away. I will start with the plug wire tomorrow. Thanks for all the information, it makes for a good troubleshooting list. I'll let you know what happens. I also moved the coil to the helm, to eliminate heat and vibration

[R Bedell]

I replaced the coil with a blue bosch as suggested by others. I finally got it, put it in, started right up, mowed and almost got done with the yard, then it happened again. I

Sounds like you have some other contributing issues.

I also moved the coil to the helm, to eliminate heat and vibration

I did that also on my 1450 and my coil is much happier now for the same reasons.

[makabart]

I replaced the the plug and wire and made it through the rest of the yard. It was still trying to die after it heated up. It seems like fuel, carb, so I will rebuild again, then go from there.

[teejk]

I think before I made work, I'd pull the plug and take a look. If heavy black build-up on the base, I'd check the gap (Kohler manual says .035, Cub manual says .025...I switched to the latter after having much the same problems...balky operation with time and belching/backfire on shutdown).