Starts in reverse, not forward.

[Docboy209]

I have a 1990 ezgo marathon. I just replaced the crank seals per a previous recommendation. It was fine at first, a bit of a long crank, but now it won't start in forward again. Compression is good. I have spark, and I can smell the fuel going out the exhaust. Plus it starts fine in reverse! I'm pulling my hair out over here trying to get this thing running again.

1990 Marathon, 3PG, running 80:1 premix, new crank seals, new intake gaskets

[trig123]

Did you stake those crank seals where they wouldn't come out ?
cartaround explains this is post number 6
https://www.buggiesgonewild.com/showthread.php?t=141805

[cart around]

I'm not going to commit to anything, but I will throw out a few thoughts.

Changing the seals fixed the original problem. It still runs in one direction, so we know the seals are still in there. We do need to question their condition.

Is one migrating, and losing its seal in one direction?

Does the crankshaft have a rough spot that is causing premature wear, that is putting you right back to where you were?

Are they defective?

You say the compression is good. What is good? I would like to see the numbers in each direction.
We recently had a cart on here with 100 psi in one direction, and 60 in the other. It had a stuck ring that wore in one spot.

[Docboy209]

Originally Posted by cart around

Is one migrating, and losing its seal in one direction?

Does the crankshaft have a rough spot that is causing premature wear, that is putting you right back to where you were?

Are they defective?

You say the compression is good. What is good? I would like to see the numbers in each direction.
We recently had a cart on here with 100 psi in one direction, and 60 in the other. It had a stuck ring that wore in one spot.

100+ psi compression in both directions. There were no rough spots on the crank. The original seals were just petrified from age. As for them being defective, who knows. I tried getting them from a local small engine shop, but they said I could get them from the same place they would, Amazon. Could it possibly be the reed valve? I don't get any pressure coming out of the carb while cranking.

As an automotive tech I'm good with newer 4-strokes, but older 2-strokes are foreign to me. Frankly I was amazed to see a hall effect sensor for the ignition. I'm to the point of saying forget reverse and throw a Predator engine on it, but it's so hard to push.

[Docboy209]

Still have no idea what's going on. The crank seals are fine. Compression is good in both directions. Anybody know where I can get a new reed valve assembly? I can't seem to find one for this engine.

[cart around]

I would rule out reed valves since it runs in one direction.

This is really weird. Running at all rules out so many things. You say it was good for a while, and then started acting up. It's almost like something slipped over time. I'm wondering if the timing moved.

Other than that I'm out of ideas because your symptoms are classic worn crank seals. I just don't know where else to go with it.

[slonomo]

On this engine, are there two pulsar coils? Maybe the one for forward is bad? Try swapping them? Just throwing it out there

What speed is the starter/gen spinning? Is it the same with forward and reverse? I've had carts that wouldn't start and it was a voltage issue getting to the starter/gen. It wasn't spinning fast enough. New battery, new large gauge cables, and good clean ground fixed the problem for me. Just throwing that out too