91 mariner 40hp dies ???

[blugilman]

hey, i have a 40 hp mariner magnum 4 cylinder motor. last two trips out motor starts normal and drives normal. trip before last we were trolling and motor started bucking and sputtering. died and restart but no accel. this occoured all the way in, die and restart. at times not starting. last trip after a run back to dock at just above 1/2 throttle motor just died. no buck, sputter, coughing, just off. got home and motor starts right up. comp is equal x 4 at around 80psi, all clylinders have spark, cleaned plugs. fuel line is new this year. boat is 06 with on board tanks. ideas help ?????????

 

[CharlieB]

Re: 91 mariner 40hp dies ???

Cleaned plugs?

Where they sooted and fouled?

Drain the float bowls and observe for the presence of any water droplets. If any water found then install a water separating filter, you may have gotten a load of 'wet' fuel.

Pump the primer while looking down the carb throats, looking to see if any fuel flooding.

 

[Riverman128]

Re: 91 mariner 40hp dies ???

If Charlie's suggestions don't correct the problem, check out the electrical system-stator, trigger, and switch box. Be sure you have a service manual. It will detail the tests. I'm not an expert, but 80#'s of compression is on the low side. I would do a decarb with Seafoam or similar product, them recheck compression. You can find the decarb procedure outlined on this website.

 

[blugilman]

Re: 91 mariner 40hp dies ???

thanks for input. plugs were wet fuel, used spark plug sandblaster to clean and replaced. seems electrical because it just shuts OFF. course it runs fine on hose in drive. toyota mechanic for 10 years, is there any auto injector or cleaner to run thru this motor to decarb it. camrys had carbon problem with valves and we ran cold water thru vac line. this aint no camry and i aint no marine mechanic. hot blue spark on all 4, tested in drive. jumped 1/2 inch gap.

 

[blugilman]

Re: 91 mariner 40hp dies ???

had boat out sunday, after a run down lake motor ran better after doing the decarb as suggested. we fish for an hour or so and motor started good but after a short move died. motor lost spark on all cylinders. spark comes and goes after cranking. plugs wet of course. when it did run bog at idle, from fuel. helppppppp