45HP Mariner A917476 Starts but dies at WOT

[Matthew Ryan]

I have a mariner 45 HP SN:A917476 with walbro carbs that will start and idle fine in the drive way and in the water but when on the water wont got to WOT. It will just die or wont go fast at all. Here is what I have done so far to trouble shoot the problem. New gas and gas tank, new fuel line, new primer bulb, new fuel line to carbs, replaced stator (low speed coil went bad), cleaned and rebuild both carbs and both fuel pumps. I am at a loss for what the problem might be. Am i missing an adjustment to a jet? I adjusted the idle screw in the driveway. Any help would be greatly appreciated.

 

[Matthew Ryan]

I looked up the motor its under #7045716 and its a 1986

 

[jimmbo]

Well, that engine will run and sound just fine on the Driveway when using muffs, even if 2 of the 4 cylinders are not producing power, as it is under no load, nor does it have to fight the water blocking the Main Exhaust.. Once in the water, under load, the story changes.

First things first, a Compression test. Does the ignitions produce a good enough spark that can jump a gap of 3/8"? When you reinstalled the carbs, did you verify the Sync between the Carbs and the Spark Advance? Any adjustments to Idle Mixture and Idle speed need to be done under load and in the water. If done on the muffs, the speed will be too low when in the water, and the mix will be too lean. The Idle speed needs to be adjusted with the Throttle cable disabled/disconnected. Once the speed is set correctly, the Throttle Cable length will need to be adjusted so there is a bit of pressure(preload) holding the throttle linkage against the idle stop. Too little Preload and the Idle Speed will not be consistant, too much and it will result in it being difficult to shift out of gear.

 

[Matthew Ryan]

i did verify the sync between the carbs i adjusted the idle mix screw in the driveway but will do in water next time. Last time I took it out I put it in the water tied it to the dock and it started up on the first crank. I let it idle at the dock for about 10 min while I went in and paid the ramp fee. Came back out it was still idling. Hopped in and put it in gear no problems. Taxied out to the channel no problems. Got out past the no wake zone and eased the throttle to WOT and only went about 10 MPH. I pulled the throttle back and jammed it into WOT the engine fell on its face died and wouldnt restart. I will do a compression test and a spark test. How do you verify the sync between the carbs and the spark advance?

 

[Matthew Ryan]

#1 75psi #2 72psi #3 74 psi #4 73psi. Did spark test with 3/8 gap #1 strong #2 strong intermitent, no spark for 3 and 4. As i stated earlier i replaced the stator is my problem the trigger, switch box or coil?

 

[Matthew Ryan]

since the #1 spot was getting the strongest spark i decided to test all of the coils on the #1 lead off the switch box and all had strong spark does this rule out the coils being the problem? If i'm holding the spark plug wire on the rubber part and get a little shock does this mean i should replace the spark plug wires? I also noticed on the 2 and 4 cylinder that the plugs looked brand new with no carbon on them and the 1 and 3 plugs did. I am leaning towards trigger problem, does anyone know how to test a trigger to see if its good? Any help would be greatly appreciated.

 

[Matthew Ryan]

Am i going down the right path for troubleshooting?