Vapor Lock?

[JSinMO]

After reading what he found , I don't thing heat persay is the issue . There are many here with these 646/8 that are not having the same problem . I have side panels on Frankie's hood and work him hard and don't have that issue with a P220 onan . I think that the quality of line just is not up to scratch for this application . I have had to use fuel injection hose instead of lose pressure hose in some applications due to the poor quality hose these days kinking or collapsing . My 2 cents , You may keep the change .

I’ve rolled this around in my head 4 time more than I probably need to. I think you hit the nail on the head.
Do I have a fuel delivery problem? Yes.

Is this a vapor lock situation or heat related? Probably.

What is the root cause? Just what you said. That line I put in is not up to the job. Not the correct line for this application.

After reading what Bob, and Noel wrote about insulating the copper line if I went that route, I decided to take your 2 cents. I stopped at the parts store today and picked fuel injection line.

Hopefully I’ll have time later in the week to switch it out and we’ll see how it runs.

Thanks for taking a look at this with me guys. I appreciate your comments and thoughts!

[Eugen]

I think that's most likely the solution Jeff, please let us know if it fixed the issue!

[JSinMO]

Let me start by saying I have no problem admitting when I’m wrong. If you can’t accept it when a theory is incorrect you’ll never learn anything, and you won’t fix anything!
Secondly I’d like to say…CRAP!

I went up to the shop tonight to fiddle with this. It’s 90 degrees with high humidity so I figured it a good time to see what happens.

Here is how I had the old line routed.

Here is how I had the old line routed.

This time I ran the line out of the engine compartment as quickly as I could.

I replaced the gas line and hooked everything back up and went for a drive. It ran good and I thought I had it whipped. I let it idle for a bit then I ran it again. Same thing happened, it sputtered and died. I could start it back up almost immediately but I have to choke it to get it to start and it keeps dying. I took the air cleaner lid off and started it and I can see gas flowing into the throat of the carburetor.

So now I’m not sure what’s going on. I reread what you guys wrote and I think the next plan of attack will be to pull the carburetor and intake and reinspect and go over everything. This issue doesn’t happen until everything is good and hot. I also could keep it running by squirting carb cleaner into the throat of the carb, making me think I have a pretty good air leak somewhere. I sprayed a around the intake and didn’t get any change, but I may not have hit the right spot.

At this point I’m still not leaning toward a spark issue. My experience with a bad coil has been that you can’t restart until its cold. You can restart this the whole time but it only runs for a little bit and sputters and dies.

That’s where I stopped for tonight. We’ll see what happens next!

[Eugen]

That's too bad Jeff! It's like this sometimes. Hope you'll find out what's wrong soon!

Your bug seems to have jumped over the border and bit my 644. When it gets really hot it starts lowering the rpm until it shuts down completely. I can start it for a bit with more choke, but then it dies again. It so happens that my fuel line is about 3 inches away from the exhaust pipe.

[propane1]

Gas cap plugged. Take the cap off and try it.

Noel

[DavidBarkey]

@JSinMO Before use do anything else check the pulse hose from the crank case to the fuel pump on the carb . And yes verify the gas cap can breathe small insects will build nest in them at times. Verify the screws holding the pump together are all snugg.

[propane1]

@JSinMO Before use do anything else check the pulse hose from the crank case to the fuel pump on the carb . And yes verify the gas cap can breathe small insects will build nest in them at times. Verify the screws holding the pump together are all snugg.

Isn’t there an electric fuel pump on this Dave ? Maybe I’m not readin right.

Noel

[JSinMO]

Yes it has an electric fuel pump on it. I don’t really like the location the PO picked to mount it, but it works so I left it

[JSinMO]

We’ll tonight I verified the gas cap is not the issue. I ran the tractor until it started acting up again. Same results with or without the gas cap. I also sprayed around the intake with carb cleaner and it didn’t help. I could keep it running by dribbling carb cleaner down the throat of the carburetor. I’m trying to fit a little troubleshooting in between other things I’m doing. I’ll just keep checking things off one by one as I can. Sooner or later I’m gonna find the issue!

[propane1]

Well. Some more thoughts. But I’m running out.

I don’t like the two filters. Could be added resistance there. And I’m not sure if the filters are correct ones. And do they have arrows on them showing direction of flow ? I had trouble with my 224 last year when I got it. I put one of those types of clear plastic filters on and could not get gas to the carb. K321 engine with mechanical original fuel pump. I had to change the filter to an all white not clear filter. Then it worked fine. I’ll find a picture of it soon. Small engine fella explained the differences, but I can’t remember now.

Maybe the fuel pump is getting hot and slowing down or stopping. Charging voltage to low to run pump ??

Lastly, float not set right. Not enough gas in bowl. And as I mentioned before, the atmospheric vent hole in float bowl plugged.

Quite a ramble for a early Sunday morning. Just some thoughts I had. Hope you find the trouble.


Noel