1975 Johnson Stinger Carbs.

[reno443]

I have a '75 Johnson Stinger that will die when I try to accelerate unless I briefly hit the choke at the same time that I advance the throttle, then it will run perfect until I try to accelerate again from a stop or load on a trailer then it will die. I have replaced everything in the fuel system ( lines, tank etc.) except the carbs and I put new kits in them. Now I'm being told by one boat mech. that I need to bore the high speed jet's larger because today's fuel is not what they were built to burn. If this is true how much do I increase the orffice size? I welcome any and all comments

 

[coolguy147]

Re: 1975 Johnson Stinger Carbs.

I have a '75 Johnson Stinger that will die when I try to accelerate unless I briefly hit the choke at the same time that I advance the throttle, then it will run perfect until I try to accelerate again from a stop or load on a trailer then it will die. I have replaced everything in the fuel system ( lines, tank etc.) except the carbs and I put new kits in them. Now I'm being told by one boat mech. that I need to bore the high speed jet's larger because today's fuel is not what they were built to burn. If this is true how much do I increase the orffice size? I welcome any and all comments

nooooooooooooooooooooooooo don't bore anything out ...

you just need a simple carb cleaning and adjustment. if you already cleaned your carbs when you took the apart (soak in carb cleaner then blew compressed air through all of the jets and passages etc) then you might just need to make sure it's(carb) sync with the timing. idle adjustment screw and idle air adjustment screw.

 

[tx1961whaler]

Re: 1975 Johnson Stinger Carbs.

Don't bore it out; you have other issues. First make sure that the carb linkage is properly synchronized to the throttle/timing. Get another mechanic.

 

[reno443]

Re: 1975 Johnson Stinger Carbs.

Gentlemen , thank you for your response. I do agree that boring is not the answer however I am now grasping at straws. I have spent this past summer looking for the problem and have repeatedly followed the book in preforming everything that you have suggested, yet no luck. I have synced everything but the kitchen sink, the carbs have been boiled and blown several times, and like I said Everything in the fuel system has been replaced short of tearing down the engine. The engine just runs to good once I tap the choke . I actually ran about 5 gallon of fuel through it without stopping, at all different speeds, even trolling speed, and then when I stopped for 10 minutes then started again , the same problem. ( side note, I am 74 years old and have been a mechanic most of my life and worked 20 years as an maint. and engr. for a large co. so I'm not a stranger to mechanics but I'm not an outboard mech. Any more help would be welcome. I will figure out this problem, I think!!!!!!!!!!

 

[tx1961whaler]

Re: 1975 Johnson Stinger Carbs.

What are the cylinder compression numbers? A cylinder leak down test would also be informative
What spark plugs are you running?
Are you running it with the air silencer installed?

 

[reno443]

Re: 1975 Johnson Stinger Carbs.

What are the cylinder compression numbers? A cylinder leak down test would also be informative
What spark plugs are you running?
Are you running it with the air silencer installed?

I don't get home from work until after 6:00 pm, I'll get this info next week end. ( I retired in '99 but never quit working )

 

[Faztbullet]

Re: 1975 Johnson Stinger Carbs.

I'm being told by one boat mech. that I need to bore the high speed jet's larger

You cannot bore or drill a jet ,it has to be reamed to size with a jet reamer.

 

[reno443]

Re: 1975 Johnson Stinger Carbs.

I don't get home from work until after 6:00 pm, I'll get this info next week end. ( I retired in '99 but never quit working )

O.K.---------- now I know, top cyl. 140psi, middle cyl. 140psi, and btm, cyl. 80psi. Anyone need a boat anchor? Thanks guys for the help. I am real surprised to see how well this mtr. runs high end with those readings.

 

[dazk14]

Re: 1975 Johnson Stinger Carbs.

Pull the head and have a look. Maybe it's just a head gasket.

 

[reno443]

Re: 1975 Johnson Stinger Carbs.

Pull the head and have a look. Maybe it's just a head gasket.

I plan to do just that today. There is one pc. of the head gasket that looks like it might be leaking water.

 

[reno443]

Re: 1975 Johnson Stinger Carbs.

I plan to do just that today. There is one pc. of the head gasket that looks like it might be leaking water.

Bingo----one leaking head gasket. The piston's have more side movement than I would expect but I think a gasket will make it run, if not I'll have to junk it, it's not worth a 500.00 repair job.

 

[tx1961whaler]

Re: 1975 Johnson Stinger Carbs.

If they all come up to 140 after a new head gasket, then that motor will be a real screamer.

 

[dazk14]

Re: 1975 Johnson Stinger Carbs.

Bingo----one leaking head gasket. The piston's have more side movement than I would expect but I think a gasket will make it run, if not I'll have to junk it, it's not worth a 500.00 repair job.

You should be fine... Those are high compression Powerheads...155+psi new is common. 140psi will rattle as you've noticed, but still be a reliable runner that's good on gas.

As you noticed, motors can build great dynamic compression (higher Rpm's) and getting cylinder 3 up to speed will take care of the lower rev's power band - which was never great for that motor.

If you can mic it, verify the new head gasket is similar in thickness to what you are removing.