Hey all,
I recently purchased an old bass boat (my first boat) with a 1976 Johson 70 HP engine. Been having trouble getting it to idle properly, even though I've done an OEM carb rebuild, new fuel pump (and lines), new gas tank/bulb/connectors, etc.
When I got it, I found that the upper and lower carbs did not have an idle screw, so I purchased the #30 idle screws. Then I found that the middle carb had a #67 idle screw. Lastly, the carb part numbers appear to be from a 1983 Johnson 75 HP engine. My motor has a fuel primer solenoid, so someone from a different forum told me that makes sense. The carbs are all identical, which has me concerned something is wrong there too? I thought they were supposed to be unique/slightly different from each other?
I can get the motor to idle if I spray a little seafoam into the carbs. At that point it runs like a champ. Once the seafoam burns off and I shut it down for a little bit, the idle problems come back.
Does anyone know if I need the #42 idle screws for these carbs since that's what size shows up for the '83 Johnson 75 parts diagram? Is that my problem?
Compression is: 138,128,138
When on the lake, I am able to get the motor going at higher RPMs if I prime it right after engaging forward, then give it throttle (otherwise it will bog down and die when attempting to increase throttle).
Thanks in advance!
I recently purchased an old bass boat (my first boat) with a 1976 Johson 70 HP engine. Been having trouble getting it to idle properly, even though I've done an OEM carb rebuild, new fuel pump (and lines), new gas tank/bulb/connectors, etc.
When I got it, I found that the upper and lower carbs did not have an idle screw, so I purchased the #30 idle screws. Then I found that the middle carb had a #67 idle screw. Lastly, the carb part numbers appear to be from a 1983 Johnson 75 HP engine. My motor has a fuel primer solenoid, so someone from a different forum told me that makes sense. The carbs are all identical, which has me concerned something is wrong there too? I thought they were supposed to be unique/slightly different from each other?
I can get the motor to idle if I spray a little seafoam into the carbs. At that point it runs like a champ. Once the seafoam burns off and I shut it down for a little bit, the idle problems come back.
Does anyone know if I need the #42 idle screws for these carbs since that's what size shows up for the '83 Johnson 75 parts diagram? Is that my problem?
Compression is: 138,128,138
When on the lake, I am able to get the motor going at higher RPMs if I prime it right after engaging forward, then give it throttle (otherwise it will bog down and die when attempting to increase throttle).
Thanks in advance!
