New Carb, Fuel Pump & have pulse at crank case but still not getting Fuel

[robstr1200]

I have a 1990 Marathon with 2 stroke engine. Bought it 2 weeks ago from a buddy of mine. It was not running and did not have a battery when I got it. I put a new battery in it, and went ahead and put a new carb on because the old one was broke where the throttle lever assembly goes into the carb. I also put a new fuel pump in thinking that may have been the problem all along because my buddy who had it before me said it ran fine and then one day it just would not start. I also took the tank out and flushed it then put it back in and put all new fuel lines and fuel filter. Added premixed gas/oil at 1oz oil per gallon of non ethanol gas . Oh yea and put a new spark plug in as well. Tried to start and engine would crank but not start. Did compression test and have 120 psi. checked the spark, and it has good spark. was not getting fuel so i used a syringe with a hose to put fuel in the carb. It started right up and ran good until the fuel was used up. I then took the new fuel pump off and held my thumb over the pulse hole in the crank case while my wife tried to start it. it had good pulse. I put the fuel pump back on thinking maybe it was not sealed good since i used the existing insulator gasket (have a new gasket ordered) i left the fuel line off the pump that goes to the carb so I could see if it is pumping fuel when I crank it. It spit out a little fuel at first but then stopped.. Does anyone have any ideas?? I have read a lot on here about crank seals blowing out and causing problems but I thought since I was getting good pulse the seals should be good. Any suggestions is greatly appreciated cause I am about to go crazy trying to figure this out!

[sthreatt]

Pretty much what you have said is that everything is new and clean and getting pulse from the crankcase, but the fuel pump is not pumping. All that being true and accurate, then the only thing I can think is that maybe you have crossed the inlet, outlet, pulse line connection at the pump. Beyond that, I'm stumped.

[CP241]

Check the pickup tube inside the gas tank. It’s tiny in diameter and clogs easily. If it’s clogged or cracked it won’t suck up any fuel. Are you still using the stock “hard” fuel line that runs from the tank under the seat to the motor? Make sure that’s not clogged also.

As a test you can take a long piece of fuel line and run it from the pump and stick the other end inside the tank. It may take a minute to prime but if it pumps fuel that way then the inlet side of the fuel line is definitely problematic.

[robstr1200]

Thanks for the suggestions guys. sorry for not replying sooner. I have been out of town for a few days. Ok so i checked and the inlet and outlet lines are correct. The lines are not blocked. I took a big syringe and tube I have for bleeding brakes and pulled fuel from the hose that connects to the fuel pump. I could see the fuel being pulled from the tank through the clear filter and I got fuel in the syringe so that tells me its not clogged. When I put my finger over the inlet of the fuel pump and crank I can not feel any suction at all. But I can put fuel in the carb with the syringe tube and it will run until the fuel is used up. When I had the pump off and felt for a pulse during cranking I could feel a pulse. Is it possible the pulse is not strong enough? Is there a way to test to see if the pulse is strong enough? Would the engine run off the fuel I am putting in the carb even if the crankshaft seals are bad? Im stumped. I have a new insulator gasket that should be here today or tomorrow. Maybe its not sealing good where the spacer connects to the engine block. Thanks for any advice and help guys!:

[CP241]

The pulse at the fuel pump wheee it bolts to the motor should be quite strong. There’s no mistaking whether or not it’s strong enough. Gut feeling is telling me if you’re questioning if it was strong enough or not, crank seals are probably suspect.

When crank seals *start* to go, it will still run if you put fuel in the carb but maybe not enough pulse to make the pump work. When they’re completely gone then there’s little pulse (if any) and it probably won’t have enough suction to pull fuel in from the carb, and not run.

Make sure the seal at the pump is good between the pump and the block. If it is, I’d check pulse with my finger again and if it’s good, replace the pump. Get a good mikuni pump not a Chinese knockoff.

[robstr1200]

Ok i went out to the Cart and took the fuel pump off again. Confirmed there is pulse there and it feels stout to me. The new insulator gaskets came in the mail. I thought there was only one gasket needed but there are two in the new pack. Is there a gasket needed on both sides of the spacer? I thought there was just a gasket between the engine block and the spacer.

[cart around]

There should be a rubber O ring on the pump that mounts to the plastic spacer and then a gasket between the spacer and engine.

[robstr1200]

ended up putting an electric pump on and wired it to the wire going to the starter generator that only gets power when the gas pedal is pushed. It ran good for two days...took it on a 4 mile Journey around the block (that's a country block) it did make it home but then quit again. I think its the crank seals. I ordered new seals for both sides. I am gonna pull the motor tonight. I will probably need advice along the way. Does anyone know of a good video or post of someone doing the crank seals? I ordered a manual on ebay and have downloaded it so I will be using it as well.