91 3pg running issue

[BrewCityMusic]

another commonly overlooked issue (which generally shows itself after the cart warms up) is a partially blocked muffler (been there done that on not one but TWO Marathons so far) ... These engines (especially those with the original oil injectors) tend to blow a lot of unburned oil throughinto the exhaust, and over the decades it build up into a really nasty sludge which, when heated, becomes slightly viscous and can block the passages in the muffler, giving You the symptoms mentioned. The easiest (and fast and free) test is to loosen the bolts at the muffler where it attaches to the headpipe so there's a 1/4" gap or so between them, then run the cart. On the downside, it's loud as he11 and will likely annoy you terribly, but on the upside if that DOES solve or aid your trouble then it's an easy free fix. Search "Muffler BBQ" in the threads for more info and pics on the procedure, there are many ways to accomplish the muffler cleanout but they DO work and in fact, I do it yearly now as it keeps things open and flowing correctly and only takes an hour or so (with almost no labor involved) to do.

[DIESELGREEN]

Thanks for the input, I have already bbq'd the muffler. Now, correct me if I'm wrong, but would it not be an optimal idea to use an electric fuel pump and cap off the fitting at the crankcase to eliminate fuel delivery issues?

[BrewCityMusic]

The pulse pumps are actually insanely reliable on these, personally I can't see the use in replacing it w an electric, etc but that's entirely up to You ... There are a ton of these 25-year-old-plus carts still rolling around on the original pumps, so it's a pretty safe bet a new one at $30 will carry you another 25 ...

[DIESELGREEN]

My problem is not the pump, I think you are misunderstanding what I'm asking. Say my crank seals could be causing loss of vacuum for the mechanical fuel pump to work properly. Leaking crank seal=fuel pump will not work properly. I am asking if this would be a feasible solution to eliminate the possibility of the cart not running due to the fuel pump not being able to feed the engine.

[1989Marathon]

An electric fuel pump will solve that problem, but that's not the only problem that worn crank seals cause. Another issue with worn crank seals is that a good seal is necessary for the fuel charge to be passed from the crankcase, through the transfer ports, to the combustion chamber. As the seals wear, this transfer becomes less efficient.
Also, be careful with an electric pump. If you have too much pressure, you may need to change out the needle/seat.

[DIESELGREEN]

Thanks 1989marathon, that was the answer I was looking for. I appreciate all the help guys, thanks again.