1981 Johnson 25HP starting issue

1981 Johnson 25, Electric start only.

Carb rebuilt and looks factory clean
All wires look in good shape
Carb is electic choke

I bought engine in "non running condition" ie the lower unit was frozen, not the head. I have no background on the motor.
Comprssion is 115 on both cylinders.

Motor starts on starting fluid but will not start on gas.

What could be causing this?

Any suggestions of what to look at? Maybe fuel pump?

Thanks!

Re: 1981 Johnson 25HP starting issue

NEVER use starting fluid on a 2 stroke, they are lubricated from the oil mixed in gas. Starting fluid will make the pistons and bearings run bare metal against bare metal, you dont want that. The conditions tells you it isnt getting gas. Make a cheap spray bottle with gas oil micture and spray it in intake while you pull starter rope or cranck it with starter. I
f it starts, you have a dirty carb ( may look pristine on outside ) a bad fuel pump, leak in fuels hoses, or similar. Find and clean the small passages in carb, screw low speed micture gently all the way in, and reverse it 1 3/4 turn from buttom.

The carb should be dissassembled, all plastic and rubber parts removed, and soaked in carb cleaner overnight. Then find all small passages, blow thru with compressed air, put a new keyhole gasket around the low speed needle, change floater valve, assemble and put back on.

Re: 1981 Johnson 25HP starting issue

1st never use starting fluid, use premixed fuel. good info here

http://forums.iboats.com/showthread.php?t=299680

Re: 1981 Johnson 25HP starting issue

I agree it's probably the carb, but I would start at the fuel pump. You can disconnect hose at the carb bowl. When you squeeze the bulb fuel should come out of hose. If so, then you know it's the carb for sure.

Re: 1981 Johnson 25HP starting issue

Thanks for the help, I took out and cleaned the low speed again and at around 1 1/4 it runs perfect now. I must have missed part of the old gasket that got in there and clogged it?

On the starting fluid the can says for marine engine and has "cylinder lubricant" I did not use it anymore and made a spray bottle of gas oil mix to use now and in the future. Hopefully the gas does not eat the bottle away.

No only concern now it stopping the engine since the choke is electric I cant kill it that way. I will have to wire in a kill switch somehow.

Thanks again for the help!

Re: 1981 Johnson 25HP starting issue

That's great news. You can throttle down to stop as well, you probably will have to adjust the slow speed stop though. I would add a kill or lanyard switch anyway. I can send pics if you like.
I have the same motor and been very happy so far. Oh, no need to keep a spray bottle with gas, just pour it back in the gas can.