Engine issue with my 18HP Craftaman Tractor..
 

As most of you remember I am in the process of restoring an 18hp lawn tractor (I got for free!).

Any ways, this project is actually moving a long quite nicely but I have run in to a strange engine issue; let me explain.

I have a manually adjustable choke which I obviously use when the engine is cold. The engine starts up fairly easy considering it's age but seems to have a problem running without the choke almost 75% engaged. If I open the choke fully to the normal running position the engine seems to starve from fuel but if I reengage the choke (closed) it naturally runs rich but I back it off and it runs strong for a few moments and dies out.

I started playing with the choke position and found that keeping it about 75% closed the engine almost seems to run normally (I actually cut the lawn like this)... Weird huh?

I have checked the fuel suction pump on the front of the carburetor but I can't seem to find an issue there. I have replaced all the fuel line and it does seem to be getting fuel; however, that doesn't seem to be the case.

I am trying to think about this logically, if I have the choke 75% engaged, would that not suggest it is a fuel problem since the choke will essentially be suctioning more fuel when partially engaged?

Perhaps a gremlin (one of my kids) has adjusted the fuel/air adjustment on the carburetor?

Any ways, I have the manual and plan to adjust the air and fuel ratios on the carburetor to see if that help but wanted to make sure I am not overlooking some thing more obvious.

Dave

Re: Engine issue with my 18HP Craftaman Tractor..
 

Thanks wildcard... I was thinking about getting replacement gaskets for the fuel suction pump on the front the carburetor thinking that I am loosing suction somewhere. Obviously that would explain my ability to counteract it by partially engaging the choke...

I am able to suction gas through the fuel filter without too much effort but it probably wouldn't be a bad thing to replace just to be sure.

The air filter is pretty darn clean at the moment so I am thinking your first suggestion about replacing the gaskets makes the most sense.

Dave

Re: Engine issue with my 18HP Craftaman Tractor..
 

I have a Cub Cadet riding mower, with a 15 HP Kawasaki engine. Two times (last year and this year) I have experienced almost exactly the same symptoms, and both times, I have had a small particle wedged into the main fuel jet.
The main fuel jet in my case, is accessible by removing the float bowl on the bottom of the carburetor. Then usually there is a recessed brass screw, with a hole going through it up through the center of the carb, from within the bowl.
I removed this "jet" with a screwdriver, and saw the small particle, blew it out, double checked, cleaned the bowl, which was virtually clean.
Reassembled, and it runs strong, like new, no choke needed.
I do have an inline filter, so these two particles have vibrated loose from something beyond the filter, perhaps the impulse diaphragm pump device between the filter and the carburetor. Will dig deeper if it happens again.

Check your main jet like this for partial plugging.

Re: Engine issue with my 18HP Craftaman Tractor..
 

Very interesting..... Good thought...

Let me give slightly more background to this. I was testing out the mower deck and everything appeared to be running fine; however, out of nowhere the engine started running strangely and this was basically the start of the problem. I will check the fuel injector and see if there is any debris there. That would make sense considering how it started happening out of the blue.

Thank you,

Dave

Re: Engine issue with my 18HP Craftaman Tractor..
 

you might also want to consider that the tractor wasn't properly stored by running it dry. This is a common problem, especially in motorcycles up here in Canada.
When gasoline evaporates, it leaves behind a varnish-type substance that can clog float-bowls, lines and jets. The options are either a carb rebuild or to let it try and eventually clear itself. Gasoline, of course, is a solvent and will actually re-dissolve these deposits after a while.

What you mention is either jetting (too lean) or an inability to get enough fuel to the main jet. As has been mentioned, rust can clog jets and fuel filters. So can gummy gas.

Re: Engine issue with my 18HP Craftaman Tractor..
 

I probably should have fully drained the tank though it is a plastic tank so I shouldn't have much rust. However, gummy gas could be in part the issue. I did add some fuel treatment in case it was older then what my friend said it was but in retrospect I probably should have just replaced it.

When I get home I will take apart the carburetor and see if I can determine if there are any problems with the gas injector.

Good thoughts everyone...

Dave

Re: Engine issue with my 18HP Craftaman Tractor..
 

Both times when mine started, was after mowing about an hour, (takes me 2 hrs to mow entire yard) and then suddenly it started starving for fuel. I immagine this is the exact time the particle was sucked off the bottom of the bowl and into the main jet.
Choking causes more suction and more fuel can flow through a partially plugged jet, it also usually has a drilled hole for cold starts, essentially bypassing or adding to the main jet, but will only have power to run within the flow limit of the drilled bypass hole for extra gas at cold start.

Anyway, mine started out running fine, and suddenly starved for fuel. Sounds similar, however there are always many variables.

Assuming everything is good mechanically (IE slipped flywheel throwing off timing excluded), you only need fuel spark and air to make it run.

Keep us informed.

Re: Engine issue with my 18HP Craftaman Tractor..
 

Dave, do a good carb cleaning. Does the fuel line have a filter on it? Might be a good time to put in one of those in line filters. Also any chance you might have a little water in the tank. That can cause similar symptoms. But it sounds like a blockage in the jets.

Re: Engine issue with my 18HP Craftaman Tractor..
 

I was thinking the same thing. Your symptoms are telling you that in order to get the fuel you need, you need to suck harder! That's probably why the choke seems to attenuate the problem. If it happened suddenly, it's almost certainly a blockage of the fuel supply, probably at the jet.

If you're not up to disassembling and assembling the carb or just don't feel like it, you might try cleaning out the tank/fuel lines, adding an inline filter, and some "Sea Foam" in the tank and then run it a while. If it's varnish, it might clear up on it's own.

If it's dirt or rust, you're probably going to have to do surgery.

Re: Engine issue with my 18HP Craftaman Tractor..
 

Its a fuel delivery problem

start at the fuel tank and work your way to the jets

blockage at the tank
fuel filter
fuel pump (if it uses one)(diaphram,valves,pulse line)
carb..float ...needle ...seat.....jetting
non-float.....passageways and jetting

easyest way to eliminate half the work is to rig up a temporary gravity fee fuel tank to the carb and see if it runs fine off of it....if it doesnt its the carb.....if it does then its the tank/pump/filter etc

Re: Engine issue with my 18HP Craftaman Tractor..
 

[QUOTE=Squirrel Bait;1718629]Dave, do a good carb cleaning. Does the fuel line have a filter on it? Might be a good time to put in one of those in line filters. Also any chance you might have a little water in the tank. That can cause similar symptoms. But it sounds like a blockage in the jets.[/QUOTE

Good advice & Tazzman also.
I had similar symptoms with water in in a fuel can. The new ethanol goes bad much faster than most of us are used to and can also cause a similar problem.

Good luck ,you'll finger it out .

Re: Engine issue with my 18HP Craftaman Tractor..
 

Thank you all for your contribution to this thread.

I am by no means mind getting my hands dirty so I fully plan to figure this out on my own (and with all of your input!). What is the use of being self reliant if you aren't willing to do your own work? I don't have a lot of mechanical exposure but I am more than capable of seeing the logic of the above suggestions.

Tazz, I like the idea of the gravity feed gas to determine where the problem is.

To be honest, I have a plastic gas tank on the tractor so my initial thought is not rust but maybe gummy gas. By the way, I have already fully replaced the gas line from the tank to the engine...

I already downloaded the schematics of my tractor engine and plan to take apart the carburetor. This will probably be a good direct approach. Worse case, if I screw this up beyond recognition I will buy an overhaul kit for it and replace the vital parts. Being that I am cheap, I will probably be very careful not to mess up any parts and try and repair this on my own.

If I can't do this simple task, then I am going to have bigger problems on the future homestead ;)

I will let you all know how things go...

Dave

Re: Engine issue with my 18HP Craftaman Tractor..
 

By the way, here is my beauty :)

http://www.cxp.com/username/tractor-start-03.jpg
http://www.cxp.com/username/tractor-start-04.jpg
http://www.cxp.com/username/tractor-start-05.jpg

Don't any of you get any ideas, this one is all mine :)

Dave

SUCCESS!
 

OK! Looks like we have a winner!!

I flushed the carburetor and boy all sorts of debris came out! Thank you all for helping me through the common sense! Obviously a fuel flow issue was the case in my situation. Just to admire how much debris I had in my carburetor I took a picture of all the yuck...

http://www.cxp.com/username/tractor-yuck-carb.jpg

Dave

Re: Engine issue with my 18HP Craftaman Tractor..
 

Nice work, Dave!

And congrats for getting it running properly.

Now cut the grass!

:15_1_70v:

Re: Engine issue with my 18HP Craftaman Tractor..
 

10-4 on that. In fact, I already finished the lawn after the joy of repairing my engine :) Let's see if that euphoria last until next week :biggrin:

Thank you again for the reccomendations..

Dave

Re: Engine issue with my 18HP Craftaman Tractor..
 

Great question considering the deck in not in the picture :D

Well, long story short, I had previously written off the deck thinking it was too far rusted to recover. Literally ALL of the pulleys were seized and the deck had a huge amount of rust on it.

Have I mentioned I am kind of cheap? Well, I am. So that being said, I spent two days taking the deck apart and flushing out and clearing all rust from the pulleys. I managed to salvage ALL of the deck hardware to where it takes literally no effort to turn the belt through the pulleys.

Lastly, knocked all the rust off of the blades and sharpened them.

The deck works beautifully and cuts thick grass without effort.

I am pretty pleased what a little TLC has done for a mower I received for free.

Dave

Re: Engine issue with my 18HP Craftaman Tractor..
 

LOL, well maybe a smidgen more than a little ;)

Nothing like the self satisfaction in getting a project like that done.

Dave

Re: Engine issue with my 18HP Craftaman Tractor..
 

I got tired of cleaning carbs on the small engines and I started using Stabil in the fuel to prevent varnish formation over the winter/year between uses. Has reduced cleaning bu 80-90% but still an occasional pluggage of the main jet.

If not working and you are lucky, the main jet is a straght shot up from the bottom center of the carb. If so, I use a set of tip cleaners for gas torches that are a number of very small round files. I start inserting a small diameter file through the jet an work up to what feels just under the jet diameter.


If this doesn't work, then it means the idle jet is plugged and things get more involved with disassembly, soaking, and blowing out with compressed air.

On edit: Forgot to mention (have a new old garden tractor with this issue). Some old engines use a plastic foam carburator float. These floats swell with the current alcohol in gas misture and stick within the carb housing. The fix is to find a brass float replacement.

Re: Engine issue with my 18HP Craftaman Tractor..
 

Good reccomendation on the Stabil. I too often think about that in the aspect of fuel preservation over long periods versus treatment to keep an engine cleaner. It makes perfect sense and would probably be something I should do with more regularity when I leave gas even for short periods in equipment or storage..

By the way, I do have a brass float in the carburetor. The gumming you mentioned to bad gas was pretty apparent when I flushed it out.

Dave

Re: Engine issue with my 18HP Craftaman Tractor..
 

I have the same engine ...same problem. On the side of the carb there is a 5/8" hex nut plug. Remove that and gas from bowl will all run out (if I remember corectly) Look inside and I believe you need a 5/16" hex wrench to screw out the jet (main jet?) I would always get little pieces of crap stuck in orifice...just remove it and blow through the hole and replace everything. Start up and it will run like a champ! I think the gas messes up while sitting in the bowl and the chucks travel into the jet . I have new gas ,new fuel filter, stabil in gas ....but it still seeme to happen within a weeks time.When you open the plug all the crappy gas in the carb bowl with any debris flushes out so when you put it back together it is good to go. Untill next week!

PS. I now have the tractor at my cabin up north and it does not happen any more! You can buy regular gas up there.No special seasonal formulation or ethynol? in the gas. Now the spindle bearings on the deck have siezed up :) Don't put those tools away yet!

Re: Engine issue with my 18HP Craftaman Tractor..
 

That is exactly what I had to do. I removed the plug and drained the carburetor plus I flushed it a few times with clean/new gas.

Unfortunately the main jet would come out so I pushed a needle in it to clear it. Based on the amount of junk that came out I think whatever it was cleared. I know what to look for now.

YEP! I had to deal with this very issue too.. This is what I did, I complete took the deck apart and by the way make sure you pay attention to your tension springs and where they go (this will save you time and headaches!). I took all of the pulleys from the deck and cleaned them of rust and then took a rust dissolving solvent and flushed them real good while spinning them with my bench grinder. This seemed to do a great job of cleaning them and un-seizing them. Now the deck pulleys work great! I can easily turn the deck belt without effort.

Thank you for your post, it sounds we had the same exact issues!

Dave