Need Small Engine Help
 

Ok I'm having some serious headaches with the engine in my ride on mower and need some help. It's got a twin cylinder 20hp Briggs and Stratton in it. The engine is experiencing a major loss of power sporatically....but only when under the load of the blades. It'll start out ok and a few minutes in fall flat on it's face. Then if you limp it along it may come back full power a little later. When it does I notice a nice puff of black smoke usually. Sometimes it'll get so bad that it just won't run anymore in gear or with the blade engaged.

I replaced the fuel feed line and had the carb rebuilt by a local mower shop because I'm too busy to mess with it. The guy said there was a little dirt in it but nothing major. Replaced the needle and some seals. I put it back on yesterday and I'm still having the problem.

At this point I can only figure that I have some sort of ignition problem...but I figured that would be an all or nothing kind of issue...not come and go.

Any thoughts would be great. Anyone know how to test the magneto on one of these?? Coil??

Thanks

ignition coils are common on those engines, and the problem will come and go. an easy way to test them is to take one wire off and see if it will run on one cylinder, then put the wire back on and try the other side. if it only runs on one cyl. then you have found ur prob. however, if you have a bad coil you need to change both. pm me your model type and code off the flywheel housing and i can get you a price on coils if needed. one more thing, vale adj. is pretty critical, but i dont think thats ur prob. i usually set them @ .007

Al....I'll try pulling the wires tomorrow on it. Just for my own general knowledge...how does it running on one cylinder signify a bad coil? I would have thought if it died it would mean a bad coil.

I can get the numbers then as well. Thanks man.

if say the left bank has the wire on it and the right does not and it doesnt run, and u switch and have the left wire off and the right one on and it runs, u have a bad left side coil. hope that explains it better.

How do the plugs look?

Ok that makes a bit of sense.

The plugs are pretty close to perfect...nice and tan. If I had a bad coil I would assume I'd have a gas covered plug?? Maybe it's just a weak spark and not completely dead?

sometimes the plugs will show no indication that they are misfiring, due to the fact that it is an intermittent problem.

Ok...well like I said I'll try firing it up tonight and pulling the wires to see what reaction I get. Hopefully this finds the problem....letting 1.5 acres of grass go uncut for a few weeks is not a fun thing to catch up on!

Alright Al here's what I found.

This weekend I think I finally did it in. The mower will only start and run for a few seconds now before dying. So tonight I pulled one wire and tried to start and it ran for a few seconds before dying. Put that back on and pulled the other wire and it just cranks...no start, sputter, etc.

Do you think I've fried both coils at this point? Or possibly something else in the ignition system?

Here's the info off the motor.

Briggs and Stratton
20 hp
Model 461707
Type 0143 E1
Code 0003085B

you got an older style engine which uses a regular magnetron coil. they also fail like the newer ones. anyhow this still could be your problem, im going to see if i have any used ones, in the mean time ill get you my price on them. they list for almost 50 a piece. just for your records part# is 394891. very common for mower shops to cary.

Ok...do you think this is most likely the culprit though? I don't want to shotgun any more parts into it than is necessary.

seems like it could be whats ailing it. did you try to keep it running with carb clean?
just to rule out a fuel issue.... in the mean time i will find out what i can about the coils

Just something else to check, is the vent in the fuel cap clogged? Try running it in with the fuel cap completely off. My neighbor's riding mower with a briggs v-twin was running fine, then would slowly sputter and die. Changed the fuel filter, fuel hose, cleaned the carb etc. etc., turned out the fuel cap wasn't venting fuel tank properly so the motor could no longer pull fuel into the carb. Maybe????

Does the motor have a fuel pump on it? My 52" Scagg (old belt drive machine) has a Briggs Vanguard 16hp V-twin and it has a small fuel pump (I think anyway), does yours have anything like this? Maybe the motor isn't getting fuel?

Chris

Gravity fed fuel system. I'll try the cap thing but that's a real shot in the dark I think.

Al...I haven't tried carb cleaner. Like I said I just rebuilt the carb and replaced the whole fuel line so it should be ok.

I'm still thinking ignition since it would start on one coil but not the other.

Al it looks like I can pick up the coils for about $25-$30 each online. Do you think I should just go for it? I'll do both while I'm in there especially since it seems to not be working at all now really.

thats a good $. id get em'

Ok. I'm gonna hook my spark tester up to the wires when I get home and see if they one cylinder is even putting anything out at this point.

Yup spark tester confirmed no spark on the one cylinder. The other was still strong though so I guess I was running off one cylinder basically all last year haha. Ordered a Briggs brand coil for $30 last night shipped.

I'll let you know if/when I'm up and running again.

Well......unless I had 2 seperate problems...it wasn't the coil!

Put the new one on this weekend and the thing wouldn't run for more than about 20 seconds without dying. Went nuts looking stuff over. Almost pulled the valve covers to check adjustment. Instead I pulled the carb back off and tore it apart. Sure enough there was all kinds of lint material in the seat. Cleaned it out and put it all back together.....ran like a champ for an hour. Then it died and wouldn't restart. Pulled air cleaner and it was literall spitting gas out the carb when I cranked.

Pulled carb apart again and found a nice little chip of metal or stone in the needle seat area again. Cleaned even better and reassembled......running great again.

So needless to say I'm not super happy with the shop that did the rebuild for me. Only reason I had them do it was because I'm so busy and didn't want to spend the time. Well I spent much more time trying to fix their half azz job! And when I called him about it he blamed it on my tank or fuel line. Well the line was new with the rebuilt carb...and my tank is plastic so there shouldn't be sediment in it really.....plus there's a filter.

What about points? I not sure if your motor has them but if you do you might need a new set.

No points.....and the problem is fixed......it was the carb.