Engine Starved for Gas

[Chartman]

Hi, Anyone who cares...

Here is an update on my situation.
A week or so ago I needed to mow the front yard (less steep) lawn only.
I filled the gas tank very full. Then, just for kicks, I went right to the steepest part of the back lawn and mowed the full length (sideways along the slope) one lap in each direction.
This is about 100 ft or so each way. There was no problem with the engine.
I then continued on and had no problem mowing the front lawn.
It appears that if the tank is very full, the slope of the lawn is not a problem; at least with a "not too hot" engine.

Today I filled the tank VERY full (almost to the cap) and set about mowing the back yard.
I completed it with no problem.
The engine still sounded good, so I went straight to the front yard.
I completed that as well, but right at the very end I thought I heard the engine sound just a little less "energetic".
I let it idle (on fairly level ground) with the lower unit disengaged as I emptied the grass catcher for the last time.
I then shut the fuel valve so I could motor to its storage berth while the gas ran out of the carburetor.
This should have taken at least 30 to 60 sec, but the engine died in 5 seconds after I shut that valve.
It was clearly in a "starved for gas" state.
I opened the valve and watched the semi-transparent fuel filter.
Fuel did not "rush" in. I opened the fuel cap and still did not see a rush of fuel, but it did (mostly) fill up.
I had no problem starting it again and getting it back to storage.
The final state of the gas tank was at least 3/4 full.
The level of the fuel in the tank is clearly higher than the carburetor.

I am not sure what to make of all of this.
The hot engine may have something to do with it.
I don't think that I am in a bad way, since it appears that if I just fill the tank high before each use, I might be okay.
Perhaps that would be the prudent thing to do.
(...but it would be somewhat out of character, for me.)

If anyone has any thoughts on the subject, I'd love to hear them.
Chartman

 

[bertsmobile1]

Nothing has changed from anything you have posted to date.
You do not have enough pressure head the get the fuel from the tank to the carb,
So either the carb float needle is sticking or mal adjusted and is not dropping like it should or something is obstructing the flow of fuel from the tank to the carb

 

[Mark Sterling]

Hmmm,,,the "significant slope" statement would lead me to suspect debris in the tank sloshing around in the tank and occasionally blocking the fuel supply.

Regards

Jeff

I have a similar issue on a left side down slope.. I looked in tank seen some grass debris sucked it out. Took off all fuel lines, tank was full... all checked good replaced a couple of loose spring clamps...just in case. No help at all, I just read in this forum carb float bowl.. will have to take a look at that.. My scag is 20 years old now... changed oils and greased mostly all I have done... need to keep it running until I can get robot mowers for my 3 acres..

 

[Mark Sterling]

Hi bertsmobile1. Thanks again for working with me on this problem.
I bought this lawn tractor used last year. There is nothing I see that suggests to me that the carburetor has been replaced, or even tampered with; but I cannot say for sure.
I think your suggestion of a sticky float needle is a good one. I haven't had the pleasure of disassembling the carb on this unit so far, but it seems like it might be in my near future.
I think it may be possible to get at those parts without removing the whole carb. It probably should not be done over the grass.
I will get the proper fuel filter as suggested by Ilengine.
I don't suppose this engine can be retrofitted for a fuel pump?
I am also wondering about that solenoid shutoff to prevent backfiring. It was awfully hot at the end of the mowing. I think there is a spring loaded needle that shuts off fuel flow to the engine unless the solenoid is pulling it open. Solenoids sometimes fail or weaken under high temperature. What if I just remove that spring so it stays open? I normally stop the engine by shutting off the fuel valve, so backfiring might not be an issue.
Chartman

I just cut off the needle point, as long as I choke it and put the gas lever in low I get no backfire..

 

[slomo]

Slope is probably too excessive for that mower. Splash lubed engines and slopes are not a good mix. So to me this is not a mower problem. Wrong tool for the job.

No pictures were provided of said slope. Is this a ski slope? The word slope was given telling me she's a steep one.

 

[Richard Milhous]

Run some carb cleaner through it... and tell us what your elevation is.