Engine Problem

[Byron Trantham]

I need some guesses about an engine problem on a Murray lawn Tractor. The engine is a twin cylinder Briggs & Stratton, 17 HP. Under load it cuts out, not like a misfire more like a stall. It doesn't quit just bogs and then goes. I disengaged the blade and it seems to run ok but I will verify that tomorrow. I intend to do all the obvious stuff, new plugs, fuel filter check the air filter, etc. If none of these "fixes" work, do you have any suggestions as to what to look at next? I hate bringing it to a local dealer because you never know what they are going to do. Thanks.

[Jim Hager]

I would take the bowl off the bottom of the carburator and dump out the junk and water in the bowl then clean out the tank. Sounds to me like you just have a water problem. If that fixes it nothing else would be required but you might had as well to change out the plugs if it has been a while.


Good luck. I'll bet water and trash is your problem.

[Byron Trantham]

I took off the air cleaner and watched the carburetor intake. First of all the inside of the carburetor is clean as a whistle. However, the butterfly does move with the stalling of the engine. That is, as the engine speeds up and slows down the butterfly moves with it. I could not find a "bowl" per se, though I am sure there is one. I use gas stabilizer all the time. Tomorrow I am going to replace the plugs and fuel filter. I'll go from there. Also I am going on line to see the Brigs and Stratton manual for this engine to see where the bowl is.

[JayStPeter]

Your problem might be upstream in the fuel system. I've had fuel shutoff valves that rusted nearly shut and caused similar symptoms.

Jay

[Tom Pritchard]

Byron, I've seen the problem that you are describing caused by overfilling the engine oil. It's easy to check and could save you some time and money.

[Steve Clardy]

The bowl Jim mentions is on the bottom of the carburetor. Takes a 1/2 wrench I believe to remove the short bolt holding it on.

[Carl Eyman]

Byron: It well could be dirt in carb., but also try this. It sounds to me when you put a load on it the engine slows down. That's normal, but if govenor doesn't open throttle to give more gas, it's going to die. So manually give it max throttle by holding the rod attached to throttle so it is at max revs when you apply load. Will it accept load then? If it does it still could be carburetor, maybe a jet is dirty. I had a similiar situation on an engine that had been submerged in water. Had to have the carburetor boiled out in acid. Lots cheaper than new carburetor.

[Jim Hager]

http://www.smallenginebusiness.com/Merchant2/graphics/00000001/YAM49-09.jpg


Here is a carburator for you to take a look at. The bowl is on the bottom next to the MZ. This isn't a briggs carburator but they look very similar. Remove the bolt in the bottom and drain out the junk. Like the Dr. says if that don't work see me in the morning.:D

[Dar Lounsbury]

I took off the air cleaner and watched the carburetor intake. First of all the inside of the carburetor is clean as a whistle. However, the butterfly does move with the stalling of the engine. That is, as the engine speeds up and slows down the butterfly moves with it. I could not find a "bowl" per se, though I am sure there is one. I use gas stabilizer all the time. Tomorrow I am going to replace the plugs and fuel filter. I'll go from there. Also I am going on line to see the Brigs and Stratton manual for this engine to see where the bowl is.
Gas stabilizers do not make the fuel last indefinitly, it only extends the fuel life. If the fuel is a year or more old, it should be dumped. The bike shops I worked in, we had problems keeping gas in the showroom bikes over the winter (4 Months) even using stabilizers. I agree with the others, it sounds like water in the bowl. Good luck.

[Ken Garlock]

Byron, stop at your local auto parts store and get a can of Berrymans(sp?) B-12 fuel additive. I have used it, for years, when the lawn mower engine get a little cranky. :( It does a good job of cleaning out the carb.

Unfortunately, you have a Briggs & Stratton engine and IMO that is 90% of your problem. I am in the same boat, this spring we needed a new mower for close up work where the Scag couldn't get. I ended up with a Snapper with a BS engine because it was the only engine I could get with an electric start. I would much rather of had the Kawasaki engine, but it didn't have the electric start that SWMBO demanded. BTW, it is a 7 Hp engine on a 21" mower that drinks gas like a college kid drinks beer on Friday night. :rolleyes:

Another thing you might check is the needle valve adjustments on the carb. One is for idle and the other is for "power"(when the engine is under load.) Don't ask which is which :confused: An engine manual should explain how to adjust the carb. I would still use the Berrymans first before tinkering with the carb....

[Byron Trantham]

Well I went out this morning and pulled the plugs - they looked great! Pulled the entire air cleaner assembly and examined the linkages. They were dirty! :mad: I pulled the fuel filter, it looked clean and passed air without any problem. I downloaded the carb adjustments from the B&S Web Site and all adjustments looked fine. Sooo, I used carb cleaner to clean the carb body and all linkages and it works - so far. I ran it around the yard for a couple turns with the blade engaged and no stalling. This carburetor does not seem to have a bowl. There is an intake manifold that couples the two cylinders and the carburetor mounts on top of that - in the middle. The air cleaner assembly mounts on top of the carburetor. The inside of the carburetor looked pristine - I mean very clean. The choke plate operated as expected and the butterfly in the bottom of the carburetor seems to work fine as well. All said and done, it looks like the linkages were too dirty. I won't know how well this fix works until I spread the fertilizer tomorrow.

Thanks so much for all the input.

[Ernie Nyvall]

Byron, if the carburetor looked dirty inside, you would be in trouble. They can look clean as a whistle, but all it takes is for a speck of dirt to clog it. I've put several carb kits on various briggs engines due to the wear on the little needle that adjusts and regulates the gas flow. Do all the other stuff first and if it's still happening, I'd get a carb kit.

Good luck

Ernie