About to lose hope... any advice will help. 1974 Mercury 115

[DylRod94]

Engine idles fine out of water, can switch gears to forward and reverse and prop spins. Whenever I put it in the water though boat will go into reverse but prop doesn't spin for some reason when it does on land?? When put into forward in the water it bogs down and shuts off almost immediately. https://www.youtube.com/watch?v=hbRgRnV5I58 there is the video from it idling in the water today. Timing was set by arrow on distributor cap pointing to the center of crankshaft, carbs have been cleaned and rebuilt and linked and synced, fuel pump has been rebuilt. I just don't understand i've tried adjusting the idle mix screw nothing really changed its sitting about 1 3/4 turned out and I'm at a loss of what to do.

 

[Jacobsele]

check compression, double check link and sync. When in water, the prop has a load when in gear. It may run fine on muffs with no load, but won't run with load and low compression. I really hope that's not it, but it's the first thing to check.

 

[DylRod94]

Compression is 115 in all cylinders and done link and sync twice

 

[Jacobsele]

I'm out of ideas for now. It would help to know the serial number of the motor, how many cylinders, efi or carb, distributor or coil packs, etc.
I'm sure other members will chime in also, but it helps to have details on the outboard.

 

[racerone]

They will " run fine " on the trailer , even shifted into gear on the trailer it is still nuetral as there is no load for the prop !!---Try spraying some mixed fuel into the carburetors and note behavior of the motor.----To me it sounds like a plugged jet in one or more carburetor.----Does spark jump a gap of 3/8" or more on all leads ?---Sounds like the shift cable needs adjusting to get reverse to engage properly.

 

[Jkcckc2002]

Check shift cable to make sure it is going all the way into reverse when shifted. Could be barely in gear and the resistance kicks it back to neutral.

 

[DylRod94]

I'm out of ideas for now. It would help to know the serial number of the motor, how many cylinders, efi or carb, distributor or coil packs, etc.
I'm sure other members will chime in also, but it helps to have details on the outboard.

1974 Mercury 1150 5 cylinders, 3 carbs, serial number 3651652

 

[racerone]

I would say one or more carburetors is not working properly.---Were carburetors dirty ?---Were they taken apart for cleaning ?----Did you find / identify the high speed jet, yes or no ?---Are the plug wires on the correct post ?

 

[DylRod94]

I would say one or more carburetors is not working properly.---Were carburetors dirty ?---Were they taken apart for cleaning ?----Did you find / identify the high speed jet, yes or no ?---Are the plug wires on the correct post ?

​I took off the carbs and cleaned them twice, they wasn't very dirty. I didn't remove the high speed jet but soaked it and blew it clean with an air hose twice. Yes plug wires are correct

 

[tavacska]

Maybe you can read my posts. I have a similar problem.
http://forums.iboats.com/forum/engi...rcury-1150-now-boat-on-water-several-problems

It turns out to be the idle mix screw set too lean.

Mine was set as 1 1/4- 1 1/2. And now it is set to be 2 1/2. It works like a charm.
You have to watch closely at the idle speed. Try to set it in water. Because there is a lot more resist there.

 

[racerone]

See post # 5 .---When you do simple , simple trouble shooting steps you can find out where the problem is with your motor.--Guessing does not work.----I am not standing beside your motor so answers to questions help just you.

 

[jimmbo]

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