Fuel additives

[jsz]

In the thread "Idle adjustment" I mentioned a problem my boat is having stalling at low RPM's. It accelerates and runs fine but about every second or third time I slow down to pick up a rider, it stalls.

I'm wondering if a fuel system cleaner would help. Valvoline SYN Power says it cleans injectors, intake valves and combustion chambers.

Have you guys ever tried any fuel sys cleaners? Did it help?

[Tanner]

If you put Sta-bil in your fuel when you winterize it (hey I've seen some who didn't) that is a fuel injector cleaner.

[chpthril]

It won't hurt, but it probably won't help. 1st, only air passes through the IAC valve, no fuel. 2nd, the injector openings on the 2 throttleboby injectors are so large (with only 2 injectors feeding all 8 cylinders) that they are, in a sence, 'self cleaning'.
Yes, It will help keep the valves, pistons, and combustion chamber clean with regular use.

[dogbert]

Your problem may be your distributor cap. Sometimes they crack. Mine did that and I had similar symptoms.

[jsz]

Thanks guys. In my trouble shooting I was wondering what the possible problems could be. Fuel sys? Injectors? Idle controller? and now dist. cap?

BTW it's a '02 with a 350 Merc MPI. Only 313 hrs. (not sure if this is the motor chpthril is talking about)

It normally runs so good that I'm guessing its a simple fix or adjustment. I'll take a look at the distributor.

[gman]

hope you find the problem and let us know

[lee]

Originally posted by chpthril
2nd, the injector openings on the 2 throttleboby injectors are so large (with only 2 injectors feeding all 8 cylinders) that they are, in a sence, 'self cleaning'.

Actually the MAG MPI Merc engine will have 8 injectors so using the fuel cleaner could help if the injectors are gummed up. The "throttle body" is just an air intake.

[chpthril]

[QUOTE]Originally posted by lee
[B]Actually the MAG MPI Merc engine will have 8 injectors so using the fuel cleaner could help if the injectors are gummed up. The "throttle body" is just an air intake.

Thanks fer settin em straight Lee. I misread jsz's post in the other thread and thought he had TBI

[spharis]

TBI- throttle body intake.

The butterfly in those will also get gummed up, making the action kind of rachety. You can use carb cleaner and a rag to clean it up; they are usually easy enough to unbolt and do a thorough cleaning on as well.

[Razzman]

Originally posted by spharis
TBI- throttle body intake.

The butterfly in those will also get gummed up, making the action kind of rachety. You can use carb cleaner and a rag to clean it up; they are usually easy enough to unbolt and do a thorough cleaning on as well.

Exactly right. Also occasionally spray carb cleaner directly into the throat and use an old toothbrush to clean whatever you can reach, it really make a difference when the throat is clean for performance and airflow. Believe it or not that will also cause a hesitation on takeoff, at least in autos it does.

[jsz]

Originally posted by Razzman
Exactly right. Also occasionally spray carb cleaner directly into the throat and use an old toothbrush to clean whatever you can reach.

Silly question but what happens to the crap that is knocked in the hole by the toothbrush? Could that clog anything else?

[chpthril]

Originally posted by jsz
Silly question but what happens to the crap that is knocked in the hole by the toothbrush? Could that clog anything else?

The Carb cleaner will soften the carbon into a paste, and then it can be wiped out with a rag. Don't spray to much, you don't want the carb cleaner to puddle in the intake manifold. Liquid does not compress, so, if that puddle found it's way into a cylinder, it could cause damage.

You can also wash down the throttlebody (with carbcleaner) with the engine idling at about 1500rpm's. Much the same way as you would fog the engine for winter.