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150 mariner on ranger 373

W

Wantintofish

New member
It starts and idles fine revs fine until under load so far I have checked compression (148-153) cleaned and replaced fuel system disassembled and cleaned carbs new stator and trigger and plugs no change. If I put a passenger up front it will plane off eventually but full throttle and trim it will only reach 4200 rpms. Without the weight up front it will just struggle at 1800 rpms. When I test at home I have fire on all 6 could it still not be firing all 6 on high after replacing the stator? Bad switchbox? Idle stabilizer? Help!
 
Model number on your '150 mariner' would help....also what prop?

Is this a new problem? Has the boat ever gotten on plane properly?

What does 'replaced fuel system' mean? Did you replace everything including the tank/lines/bulb/connectors/filters/carbs/etc or just the fuel lines?

By cleaned carbs do you mean rebuilt with all new welch plugs and a total tear down or just sprayed out with carb cleaner?

How old is the fuel that's in the boat?


Compression looks good, you need to check spark with an air gap tester. It needs to jump a half inch or so with a hot blue snap of a spark. But get back to us with more information so we can better help you diagnose your problem.
 
Just acquired the boat on a trade. So no idea if it has ever worked properly. By replaced fuel system I was trying to say that shouldn't be the problem without having to type replaced all fuel line replaced fuel filter replaced bulb and installed in the correct direction removed and cleaned fuel cell. Even ran on a different cell that performs flawlessly on another boat replaced electric fuel pump rebuilt onboard fuel pump. Have tried bypassing each one at a time of course by disassembled and cleaned carbs I mean took all apart gave a soak in solvent cleaned all orifices adjusted floats to the top of the gasket surfaces. Welch plugs ... No but when I run these carbs on my friends 150 merc they run perfect. The fuel was just put in after all the cleaning I am running a very precise 50:1 mix The reeds all look fine and open and close as the motor is cranked without carbs. I'm at a total loss No idea what to do next. I have worked on motors for many years and am pretty good with a wrench. But this one beats me so far
 
When I test at home I have fire on all 6
Click to expand...
Use a spark test board to compare all six side by side. You want a loud snapping blue spark that jumps 7/16" gap. Orange or white spark is weak.
 
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