1150 Tower of Power Fuel Problems

[JON SUTTER]

Serial # 6525042 1150 Tower of Power.
Carbs rebuilt.
Fuel pump rebuilt.
Advance pivot secured properly.

Out of Water Hose Bib running.
Engine Hard to Start.
Once started constant pressure of the Fuel Line bulb to keep idle.
Engine has great acceleration.

On open water,
Hard to start, Fast idle used.
In to forward with some choke.
On Acceleration the engine stalls,
Choking keeps it going and then 1/2 to full power available.
At mid throttle the engine is pulsing with PRM up and down.
At Full power engine is a Monster.
Super fast.

The local Ace Mechanic believes there is a leak in the crankcase. The engine at lower RPM is not getting air through the carbs.

I would appreciate learned advise from someone who may have lived through these symptoms and knows where the problem lives.

Thank you

[rock]

Dare I say labyrinth seal. Welcome to the site.

Rock

[skialot2]

I had a problem similar to yours about 30 years ago on a 1989 115 4 cyl Merc. It was the antisiphon valve on the gas tank. Try using a remote fuel tank and see how it runs. To check for a crankcase leak, with the motor running, spray some carb cleaner on the seams where gaskets could be leaking. if the RPMs change you have a leak.

[Mrzip]

Carb Job Needed..

[SS170]

Dare I say labyrinth seal. Welcome to the site.

Rock
I just freshened up my 150. Put in one new reedblock and one slightly used one. Idles beautiful and takes off like a rocket. The reedblocks are the labyrinth seals. If They feel sloppy on the crank, they’re bad.

[Dave S]

Yes.....worn reeds........this motor sounds like carbs are set too tight.........

[JON SUTTER]

Thank you all for your input. I have not torn down a Mercury before and the Labyrinth term was a mystery until SS170 clarified it; reed sets and stops. The Carbs have been done by a pro. Sadly he is too busy to help with an old motor. The fuel systems has had multiple tanks and hoses tried.
I am ordering all new seals for the crank case and a complete set of reed sets and stops. I am a novice at Mercury engines but it is try or scrap the engine. Any hints or what out for would be appreciated.
Thank you

[rock]

It's not the reeds and stops it's the cages.

Rock

[JON SUTTER]

Rock,
Please, what is the official name of "Cages" and how do they go wrong.
Thanks

[rock]

The official name is reed cage and to my knowledge are NLA. On the inline 6 the crankcase runs thru 3 reed cages. The labyrinth seal is not really a labyrinth at all. Just a bunch of grooves designed to separate flow from cylinder to cylinder. Due to the length of the crank, there is some deflection that allows the crank to wear the inside of the cage. Once there is enough slop you lose the seal. I have heard of people stretching an o-ring over the crank to create the seal, but I personally can't imagine that being possible however one of the peeps that made that claim is pretty solid, so I don't really know. I have thought about machining a recess in the cage to receive a seal that you cut in half but have never done it. If you want a better explanation pm your phone number and I will try to explain it better. Good luck.

Rock

[rock]

This picture demonstrates why I never became a photographer. It also shows an inline reed cage. You can see the grooves I spoke of, barely, where the crank passes thru the cage. That is where the wear is.

Rock

[JON SUTTER]

Rock,
Thank you for the information and instruction. I am just starting the break down. It will be sporadic as I have other demands. As I go forward and discover what i do not know I will ask for help again.
Jon
206 391 5677