Merc 150 XR6- Sputter at 1/2 to WOT- Help...

[mikemac]

So i just got the boat back from the mechanic. I had a sputter problem at 1/2 to WOT. I winterized the tank and ran Stabil through the motor and fogged the motor prior to storage last winter. Before I took it to him, I thought it was an ethonel problem, so i replaced all the gas in the tank, vacuumed it, replaced all the fuel lines, primer bulb, ran seafoam through it, changed the plugs, drained the fuel/water separator, checked the fuel vent, changed the fuel filter.....

Mechanic ended up rebuilding the carbs.

Got the boat back two weeks ago and took it out. Ran great. I had it WOT for about 30 mins.

The next day I filled the gas tank, put in a can of Stabil (blue ethenol marine formula) before I fueled it up, and I topped off the external oil tank with Merc 2 stoke synthetic blend oil. Put in about 35 gallons of gas added to the 10 gallons already in the tank. We out and had a litte sputter at 3/4 throttle but nothing major. Maybe I was being paranoid.

Last weekend I got out, and once again it starts sputtering at 1/2 throttle and my gauges went dead. I pulled the cowl and the harness to my controls disconnected itself. I put it back together, taped it and started out again.

As I'm going, it keeps sputtering. So, again, I pulled the cowl and found that the fuel enrichment line on the left side of the carb was split and it was leaking fuel and probably sucking air into the carbs. I cut back the line, reinstalled it on the side of the carb and tried it again.

Sputter is now worse and at most RPM ranges expect idle or just above idle.

Is it possible that the carbs got plugged up again? Is the idle/mix screw or jets not set properly? Is there moisture in the external oil tank from when I added a brand new gallon of Merc oil? I'm getting extremely frustrated. Any help is appreciated. Thanks.

 

[j_martin]

Re: Merc 150 XR6- Sputter at 1/2 to WOT- Help...

Something's coming apart with the gasohol fuel, and plugging up things. When I rebuild carbs, I replace all the rubber lines. It sounds like that didn't happen.

There were some fuel tanks of that era that would disintegrate into the fuel with ethanol.

When you keep paying someone to go through it, it could get pretty expensive. None of the work is rocket science. A shade tree mechanic with Sears and Sawbuck tools can do it.

Best bet would be to get it right (again) and then install all new lines including the primer bulb line and the bayonet fittings if plastic aftermarket fittings have been installed. Then the first stop from the fuel tank should be a 60 GPH fuel filter/water seperator.

Went through all this multiple times on my XR4. When I finally just did it all right and put in the filter, I haven't had to do anything except crank on a new cartridge each spring annual.

Whatever you do, don't run it starving. You can burn down that hot rod in a minute or less under those conditions.

hope it helps
John

 

[mikemac]

Re: Merc 150 XR6- Sputter at 1/2 to WOT- Help...

I replaced fuel line from the tank and replaced the primer bulb. Are you saying to replace the remaining lines from the primer bulb to the carbs? Should I replace the vent line and filler neck too?

What are bayonet fittings? Are they the plastic couplings to attach the fuel lines together like splices?

I have a Racor fuel water separator, brand new last year.

Do you think it could be electrical?

Thanks.

 

[j_martin]

Re: Merc 150 XR6- Sputter at 1/2 to WOT- Help...

I replaced fuel line from the tank and replaced the primer bulb. Are you saying to replace the remaining lines from the primer bulb to the carbs? Should I replace the vent line and filler neck too?

What are bayonet fittings? Are they the plastic couplings to attach the fuel lines together like splices?

I have a Racor fuel water separator, brand new last year.

Do you think it could be electrical?

Thanks.

Well, you said the enricher line had disintigrated. Wouldn't the other fuel lines also be compromised?

The Racor filter should block just about anything that's going to hurt you, included seperated ethanol.

If the fuel line has a disconnect at the engine, that is a bayonet fitting. If it's plastic, it's aftermarket, and the bore is too small to service this engine. Unless you need the disconnect, you can bypass it and run the rubber right to the oil mixing T.

I'm not a mystic. It could be anything. Without a few tools and systematic diagnostics, you can spend a lot of money on unneeded parts.

hope it helps
John