1975 Johnson stinger 75 hp

[Brian12345]

Hey guys I’m stumped. So I bought a boat last year with a 75hp Johnson stinger took it out soon after purchase and it ran solid for about an hour then it died had and I had to be towed in. Got it on the trailer got it home and it would start right up I was told it was the fuel pump so I replaced it not even thinking. And went and got a trolling motor just in case and went for round 2 had a hell of a time starting it in the lake this time and it ran for about 15 minutes and died again. That took me into winter and this summer it’s even worse cleaned the carbs out and put a new fuel tank on and I can get it started with the choke wide open but it does instantly I have replaced the fuel pump fuel tank all new lines with no leaks. Cleaned the carbs and replaced the plugs. I’m stumped also a 3 cyl and yes all 3 carbs were cleaned. Last year it would run on muffs all day long. This year I can barely get it to turn over. All help appreciated

 

[dingbat]

Hey guys I’m stumped. So I bought a boat last year with a 75hp Johnson stinger took it out soon after purchase and it ran solid for about an hour then it died had and I had to be towed in. Got it on the trailer got it home and it would start right up I was told it was the fuel pump so I replaced it not even thinking. And went and got a trolling motor just in case and went for round 2 had a hell of a time starting it in the lake this time and it ran for about 15 minutes and died again. That took me into winter and this summer it’s even worse cleaned the carbs out and put a new fuel tank on and I can get it started with the choke wide open but it does instantly I have replaced the fuel pump fuel tank all new lines with no leaks. Cleaned the carbs and replaced the plugs. I’m stumped also a 3 cyl and yes all 3 carbs were cleaned. Last year it would run on muffs all day long. This year I can barely get it to turn over. All help appreciated

Sounds like you need to start with the basics…. Compression test and spark jump test.

 

[racerone]

Running with 50:1 mix ??----Did you install a new water pump impeller ?----Tested the overheat horn ??----Changed gear oil in the lower unit ?

 

[Brian12345]

Running with 50:1 mix ??----Did you install a new water pump impeller ?----Tested the overheat horn ??----Changed gear oil in the lower unit ?

Yes 50:1. Didn’t know about the overheat horn. I did change the gear oil.

 

[Brian12345]

Sounds like you need to start with the basics…. Compression test and spark jump test.

Compression is good and all within 10. And I have visible spark I don’t have a spark tester

 

[Brian12345]

It will stay running with the choke wide open but as soon as I let the choke off it dies

 

[racerone]

You meant to say with CHOKE closed it will run and then when you open choke flappers it stalls ? ---I think that means you need to revisit carburetor work.----Find the high speed jets ( orifice plugs ) in the carburetor bowls.---And what are the actual compression values.-----You can help yourself by posting accurate information.-----Nobody can see , hear or touch your motor on the computer screen !

 

[Brian12345]

You meant to say with CHOKE closed it will run and then when you open choke flappers it stalls ? ---I think that means you need to revisit carburetor work.----Find the high speed jets ( orifice plugs ) in the carburetor bowls.---And what are the actual compression values.-----You can help yourself by posting accurate information.-----Nobody can see , hear or touch your motor on the computer screen !

Yes sorry with the choke closed it will ruin. Compression was 120 120 130

 

[jimmbo]

You cleaned the carbs last year? Did you drain them, or use a Fuel Stabilizer, prior to the Winter Layaway?
When you were cleaning them, did you remove the Core Plugs, especially #5, and get the gunk out of there? Is #38 in good Condition?

 

[Brian12345]

You cleaned the carbs last year? Did you drain them, or use a Fuel Stabilizer, prior to the Winter Layaway?
When you were cleaning them, did you remove the Core Plugs, especially #5, and get the gunk out of there? Is #38 in good Condition?
View attachment 380433

Cleaned this year. But going to revisit them today

 

[racerone]

Check item # 40.-----And 120 PSI is low for that motor.----Yes it is.----So test with a gauge.----Or remove cylinder head for a look.-----Head gasket is cheap.