Oliver 550 carb issue

super99 · May 25, 2019

I bought a 6' Brush Hog mower for the 550 to have something to do. It started out good, but when it got under a heavy load, it started missing and sputtering and dropped RPM's. Step on the clutch and it would come out of it. I checked the spark plugs, one wire was iffy, so I found another and then they all had good spark. With no load it goes from idle to wide open smoothly. I soaked the carb last winter and put a new kit in it. When mowing, I tried opening the main jet a couple of turns, it helped a little but didn't cure it. It's been too long since I did much with a gas tractor, it finally dawned on me to try pulling the choke out. I was mowing and hit a patch of tall grass and it started sputtering. I pulled the choke out about 3/4 of the way and it smoothed out, leaned into the load and purred right along. Looks like when I get some extra time, the carb comes back off again. Chris

Duner Wi · May 25, 2019

I have an IH that does the same thing when brush hogging usually a mile from home. What I do is cross 2 plug wires to get it to back fire.
My firing order is 1 3 4 2 . I cross 3 and 4 cause they are easy to get too. So far that has fixed the problem. Rev it up a few time and get it back fire and see if that cures it.

JD Seller · May 26, 2019

Chris try putting a different coil on it first. I have had coils break down under load. They would act like a fuel issue in that the richer fuel mixture would fire but would soon soot up the plugs. I had a JD 1010 that was terrible about this. I fought it for over a year thinking fuel issue, replaced the coil and it ran fine.

dzc3 · May 26, 2019

Try opening the main jet another turn..

Oliver550Dave · May 26, 2019

I agree that it could be ignition coil - had that issue on a 9N with similar characteristics one time. Would work for a while, then sputter, then die. Come back a few hours later and run fine for a while, then die again. A new coil fixed that.

Otherwise, I noticed that you put a new kit in the carb last winter. Did that include a new main jet?? If so read on to what happened in my Oliver 550:
Check that the hole in your new main jet is as large as it was in the old jet. Replaced one in my 550 in 1986 or 87 that was labeled with correct part # from Oliver/White. Tractor would crank, run fine at low rpm, but had to pull out the choke for it to run at working speed. Subsoiled, disked, and sowed 10 acres of pasture. Kept trying to figure out what was wrong as my brother said there must be a piece of trash in it somewhere. Still had the old jet (broken-wrung into two pieces when I pulled too hard on the wrench while tightening the jet!!) and happened to observe that the hole in the old one was larger. Drilled the "new" one out to the same size and the choke didn't have to be pulled out anymore!!

Oliver 550 carb issue

super99

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Duner Wi

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JD Seller

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dzc3

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Oliver550Dave

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