80 Johnson 70 hp won't stay running

I pickup this boat, motor and trailer this summer. Trailer was in pretty good shape. The boat , 18' BlueFin, was gutted. Have refurbished. Now I'm down to the motor. It has set idle for 8 years. Cleaned it up, took filter and gas pump apart and cleaned. It looked good. Gas lines are soft, flexable and look like new. Carb's look clean and leankage works good. Plugs look good [.040] did not replace. Compression of 130 psi in each cylinder. Bought new gas line assembly. Blub pumps up hard. Using fresh 50:1 mixture.
When starting, engine starts and runs for 2 to 3 seconds and then quits. It sounds like it is running good, but then just quits like it is starving for fuel. Thinking of getting a carb kit. Appreciate any help. Thanks!!
Navyblue

Re: 80 Johnson 70 hp won't stay running

definately rebuild carbs. It took me longer to remove (6) and install them back on the engine.
Many suggest spraying pre-mixed fuel into the carb throat to verify but after 8 yrs its a dead ringer for gummed up old oil in the jets given the symptoms.

Re: 80 Johnson 70 hp won't stay running

Jonesg, sorry it took me so long to get back but thanks for your response. I ordered a carb kit and started to rebuild. trying to remove orifice, my screwdriver head is to sloppy. I'm tryiing to find a special tool OMC No. 317002 can you or anyone help. Thanks!

Navyblue

Re: 80 Johnson 70 hp won't stay running

I took a screwdriver and ground it to fit.
You'd need to grind away the flare on each side to narrow the blade.
Imagine a peice of 1/8th inch dia music wire with a screwdriver blade broubd on the end, with a handle and thats what it looks like.
I used a 3 inch dia cutoff disk in a drill to grind.
The disks are sold in the airtool section of home depot and they sell the drill adapter for the cutoff disk there too.
The blade needs to be narrow to fit the slot and deep enough to get a good grip.

If worse comes to worse then clean the orifice with wire, carb cleaner and compressed air if possible.

You should be able to get it out though.

Re: 80 Johnson 70 hp won't stay running

jonesg:
Well I guess I'll try to reshape one of my screwdrivers. Let you know how it goes. Thanks

navyblue

Re: 80 Johnson 70 hp won't stay running

Theres a sketch in the FAQ files showing the shape required.
I can't find it.

Re: 80 Johnson 70 hp won't stay running

Hey jonesg:

I've been busy and got the carbs overhauled with my homemade # 317002 screwdriver. Boy were they in need of a cleaning. Everthing went suprisingly smooth. She started right up on the water hose. Took her out on a shakedown and she running great. Thanks for your help!

navyblue