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Engine trouble, need he(Update: Mostly fixed)

Started by pyrocasto, February 06, 2011, 05:17:43 PM

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pyrocasto

Ok guys, I'm posting this around for some help. Several months ago I had a small engine shop tweak my wisconsin engine and tune her up nicely, and she ran wonderful. Since then, I put it aside and built the mill. Well, now it's winter time I switched out the gas and sprayed the carb down with cleaner. Engine doesnt want to run better than idle.

Mostly runs smooth with or without load on idle, and as you throttle up it sputters and backfires and eventually stalls. I have been cutting wood on idle lately.

Now, any ideas what the problems could be. I have the carb idler screw at maybe 1/4 turn from closed, because it was running too rich. Checked all the wires, polished the points, timing hasnt changed, added a small fuel pump, and changed the plugs. Since then I've ran it about 10 hours, and it's still covering the plugs with black carbon and running poorly.

Cant get any friends out to help, and it's not easy to take the engine to the shop(it weighs 450lbs and is bolted on the mill). It's a VH4D wisconsin engine.

Any suggestions? Feeling a bit frustrated...

Chris

Magic Smoke

If it has sat for quite sometime the fuel has probably varnished and gummed up the carb. Spraying carb cleaner down the throat of the carb really doesn't do anything, you have to disassemble the carb and spray all the tiny passages within the carb. Always use fuel stabilizer when you're not going to use the engine for a while...running it out of gas doesn't work as there is still fuel in the small passages of the carb.

dukndog

A couple of things come to mind. Check your muffler and see if it has a spark arrestor. Sometimes these get built up with carbon then rust which limits the exhaust thus limiting the intake. There should be a clean out plug there on the muffler.
Next would be to check the float and needle in the carb.
Let us know what you find!!

DnD
WM LT-15G25 w/PwrFeed, Mahindra 3510, Husky 385xp, Stihl MS261 and a wife who supports my hobby!!

ladylake

Quote from: Magic Smoke on February 06, 2011, 05:38:36 PM
If it has sat for quite sometime the fuel has probably varnished and gummed up the carb. Spraying carb cleaner down the throat of the carb really doesn't do anything, you have to disassemble the carb and spray all the tiny passages within the carb. Always use fuel stabilizer when you're not going to use the engine for a while...running it out of gas doesn't work as there is still fuel in the small passages of the carb.

Right, I think running it out of gas is worse than leaving fuel in it as the small amout left will turn to gunk for sure, best to add stabil or sea foam and try to run it more. Give the carb a good cleaning , take the adjusting screws out(screw all the way in and count the turns so you know where they were set) and spray some cleaner and compressed air through the jet holes as thats the most likely place that the carb is clogged.   Steve
Timberking B20  18000  hours +  Case75xt grapple + forks+8" snow bucket + dirt bucket   770 Oliver   Lots(too many) of chainsaws, Like the Echo saws and the Stihl and Husky     W5  Case loader   1  trailers  Wright sharpener     Suffolk  setter Volvo MCT125c skid loader

red oaks lumber

take the carb all the way apart, start spraying everything with carb cleaner then reassemble.
the experts think i do things wrong
over 18 million b.f. processed and 7341 happy customers i disagree

moonshiner

Sounds like a plugged main jet.Like the others say you will need to take the carb apart.Soray it down real good and inspect the main jet real close.If there is any debree in it at all the engine wont run rite.After cleaning it if you still have doughts take a piece of multistrand copper wire,strip about an inch of it and use it as a reamer.Be careful,size the wire to the jet and carefully twist in it.PLEASEdont use anything harder than copper it will damage the jet.Also check the carb vent it may be plugger.Had that on my tractor like to never figured that out.Good luck.

pyrocasto

OK so far the general advice was to the carb. I took it apart before and sprayed it down to no avail. Today I took the jets out, made sure everything was clean, soaking it overnight and I'll reassemble tomorrow. Looked pretty good from the start though.

Interesting idea with the exhaust dukndog, and I'll check that as well.

The carb on it is L63, on page 42 of this document.
http://www.wisconsinmotors.com:8080/wm/images/catalogs/accessory/carb.pdf

sgschwend

On idle the low speed jet is providing the fuel to maintain the proper mixture.  When the throttle is open the main jet needs to provide the fuel.  It appears that this is not happening.  The mixture leans out and that results in rough running, backfires and the engine dying.

I just repaired a Kohler and found that the small port from the fuel bowl to the main jet was plugged.  Your lucky mine wouldn't even start.  You should be able to spray carburetor cleaner up the main jet and see it spray into the throat.

In looking at your carb.pdf it is hard to see where to check, but you main jet is number 36 and number 34 looks interesting.  I would verify fuel is reaching the main jet and that item 34 does not have a blocked vent.
Steve Gschwend

sjgschwend@gmail.com

pyrocasto

Ok well I cleaned the heck out of the carb, scrubbed the carbon off the plugs and fired her up again tonight and tried some tweaking. Really couldnt get it to change much but I did mange to get it to throttle up. Just Backfires and sputters while changing throttle and under load, but still had better power. Ran it at about 2/3-3/4 throttle and cut a few more pieces of cherry.

Idler/air screw still doesnt feel like it's doing anything. I'm gonna double check the exhaust tomorrow to make sure it doesnt have too much buildup/back pressure at full throttle.

Even tweaked timing a touch while running faster to the smoothest point.

pyrocasto

MOSTLY FIXED!

I paid a visit to the guy who did the valve job and tune up several months ago to chat about it(who randomly also used to run a sawmill  ). First thing he said after telling him about cleaning/checking off fuel problems was electrical.

I sanded the points, cap, and every connection in the distributor and covered each with dielectric grease for better conductivity and to stop future corrosion some. Reset the gap as it was a smidge small. Changed the plugs while at it, and ran it without a muffler just in case.   

Ended up running pretty decent. Idle sounds better, throttles up fully, plenty of power. Slicing through 16" pine like it's not there so I'll probably speed up the infeed too.  Ready to test it better on a 24"-36" beast as soon as someone brings me one!  8) Scared to try a 48"er but one day, one day...

Thanks for the help guys.

moonshiner


pyrocasto

Well after setting overnight and running again its condition deteriorated again. It's still running better than it was, but not much. I'm thinking the plugs are getting coated quickly. Only question is, whether it's too much fuel and if so how to adjust that, or whether it's bad plug wires causing poor ignition and missfires.

ladylake

Check the point gap again, a bit to wide will cause them to float a higher speeds. Also new plug and coil wires. If it was running good yesterday and not today I'd think electrical as the carb shouldn't change overnite.   Steve
Timberking B20  18000  hours +  Case75xt grapple + forks+8" snow bucket + dirt bucket   770 Oliver   Lots(too many) of chainsaws, Like the Echo saws and the Stihl and Husky     W5  Case loader   1  trailers  Wright sharpener     Suffolk  setter Volvo MCT125c skid loader

pyrocasto

Twas. No seal between the distributor cap and distributor is letting too much moisture in I believe. Already re corroded the points. Little scuff and it's running smooth again.

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