Lt40 Help!! Onan 24 will only run full choke.

Al_Smith · August 11, 2012, 08:56:58 AM

I'll tell you what might help on these small engine carbs is a set of tip cleaners used on a cutting torch .Buy the long type .Often they will punch through those little passage ways where compressed air will not nor will carb cleaner .

For some reason it seems the aluminum kind of flakes off and clogs the jets and passage ways I suppose due to the fuel .Whatever causes it it becomes a monumental pain in the buttocks at times .

Another thing it could be just by the nature of the usage of the engine is teeny tiny wood fibers that find their way through the fuel filters .Doesn't seem possible but if it can happen to chainsaw a sawmill engine is not immune to it .

ladylake · August 11, 2012, 09:25:09 AM

Quote from: Peder McElroy on August 07, 2012, 06:13:29 PM
I got it to run today by squezing the bulb on the gas line and a new filter,but still not right. Do you think a dull blade would cause the motor to work too hard and heat up? It runs good at first and then 1/2 way through the log it runs bad (after about four cuts).

It's not going to make 4 cuts with a clogged carb, it could with a clogged gas tank vent. I'd check the coil known for heating up and not working. Steve

Peder McElroy · August 11, 2012, 10:39:12 AM

Thanks all. I'll keep trying and let you know when I finally get it run the way it should. The good thing is that I don't have any logs to cut at this time.
Peder

Magicman · August 11, 2012, 01:54:40 PM

Quote from: Peder McElroy on August 07, 2012, 12:41:29 AM
My onan 24 will start and run for awhile at 1/2 choke and then die unless I put in full choke.

Has this changed?

ladylake · August 11, 2012, 03:18:54 PM

Quote from: Peder McElroy on August 07, 2012, 06:13:29 PM
It runs good at first and then 1/2 way through the log it runs bad (after about four cuts).

As I said with a clogged carb it's not going to make 4 cuts, could be a clogged tank vent or partially clogged or cracked fuel line which would be checked by checking the gas supply coming to the carb. I'd sure check the for good spark right after it started acting up. Steve

millstead · August 11, 2012, 03:42:16 PM

check the compression alot of times an engine with a dead cylinder will run with the choke closed and as the engine warms up it will run worse to the point where it wont run at all

ladylake · August 11, 2012, 04:30:23 PM

Quote from: millstead on August 11, 2012, 03:42:16 PM
check the compression alot of times an engine with a dead cylinder will run with the choke closed and as the engine warms up it will run worse to the point where it wont run at all

Good idea, also might need to get the valves adjusted which could tighten up when hot. Steve

Chuck White · August 11, 2012, 04:38:01 PM

Will the engine run right when you are only at an idle?

Will it run for ...... say......20 minutes, at an idle with no problems, and then when you go to full throttle it acts up?

Peder McElroy · August 11, 2012, 04:48:53 PM

Problem fixed. Fuel pump!!! I set up a gravety feed tank and bypassed the fuel pump and it ran for 15-20 minutes at low speed no problem.
Thanks to all for all the ideas.
Peder

Chuck White · August 11, 2012, 05:36:57 PM

Peder; Glad to hear you've got it figured out! Now you can sleep right!

I got a replacement fuel pump for my Onan at the local lawn mower and chainsaw shop.

It is a fuel pump designed for the DR© equipment.

It doesn't line up the same as OEM would, but it does work well.

Cost = $14.00 (2 years ago.

Magicman · August 11, 2012, 06:35:06 PM

Plus you had a Forestry Forum load of technicians fly to your assistance and you now know everything that could possible go wrong in the future. What a great bunch of guys.

Peder McElroy · August 11, 2012, 08:08:43 PM

AMEN.

woodmills1 · August 12, 2012, 08:58:04 PM

nice

I have a cat now but I kinda miss my Onan, it was good to me

ladylake · August 17, 2012, 07:08:45 AM

Pedor, hows the Onan running with the new fuel pump? Steve

Peder McElroy · August 17, 2012, 11:29:27 AM

It's working perfect.I got a fuel pump from a Briggs and Stratton. The mount is different but I made it work. $25.00
Peder

Al_Smith · August 17, 2012, 11:53:54 AM

I had wondered if in fact a diaphragm pump from a Briggs would work or not . On that I order diaphragm kits two -three at a time because I have several Briggs engines that seem to get maybe 4 years more or less before the things get stiff and inoperative .They're fairly cheap .

It's just a simple matter of knowing given enough time they will get funky on you .Rather than fiddle around a week getting a kit shipped I have one on hand when I need it .