help with 150hp johnson faststrike

[chad26]

i have a 97 150hp johnson faststrike and when i am at idle speed 1000 to 1200 rpms the motor will just rev up to 2500 to 3000 rpms. i can turn the engin off and restart it and its fine but after about 10 sec or so it will happen again. if i turn it off and restart and jump on plane its fine till i slow back down to idle speed. it smells like its running rich and it runs like crap when it does this. had a mecanic adjust the carbs, new power pack, tune up, all that stuff still cant figure it out. had a guy tell me it could be a lenkage problem maby something sticking. or maby it could be the rvo pump that mixes the oil with gas could be bad. it seems to only do this when the motor is warm and it happens every now and then. any sugestions would be appriciated. thanks



Modified by chad26 at 12:17 PM 9/2/2010

[ChampioNman]

Sounds like you have an air leak somewhere. Check the 4 bolts on each carb body that attach them to the intake manifold. They are 3/8".

[316jughead]

Is the motor running like crap and then the RPM jump? How does it run after the RPM jump? Will the motor return to idle when taken out of gear?

[chad26]

motor runs fine before the rpm jump. when it idles up is when it runs crappy. if you put it back in netural it still idles high. if you give it more throttle it just bogs down you have to turn the key off and restart the engin and everything is back to normal until about ten seconds later it does it again. had a mecanic replace the idle jets in the carbs he said he talked with omc and they recomended to do that we'll see what happens come saturday im going to replace the port head temp sensor also if this dosent work

[ChampioNman]

Wouldn't it be easier to check the head temps? You will know for sure if you have a temp problem or a sender. You could always just disconnect the white/black quick start wire at the head.

[316jughead]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by chad26 &raquo;</td></tr><tr><td class="quote">motor runs fine before the rpm jump. when it idles up is when it runs crappy. if you put it back in netural it still idles high. if you give it more throttle it just bogs down you have to turn the key off and restart the engin and everything is back to normal until about ten seconds later it does it again. had a mecanic replace the idle jets in the carbs he said he talked with omc and they recomended to do that we'll see what happens come saturday im going to replace the port head temp sensor also if this dosent work</td></tr></table>

If the motor does this again, push in on the key to activate the primer system. If the motor smooths out or the RPMs increase it could indicate an air leak.