No Throttle on an 80hp merc?

[tireman357]

Hello all, New boater here. I bought a boat, it's a 17' something ( I dont want to say because I will get flamed ) Anyways, the motor is a 1972 merc. 800 outboards. It runs great at idle and rev's fine in netural or in gear in a 55 gal. barrel. When I take it out to the river, it has no trottle. It will go into gear and if I feather the choke I can get maybe 9 mph out of it at WOT.

I am a automotive Tech but 2 strokes are a foreign language to me. I did do a compression check 149-151 across the board. Ignition wires test fine,new gas and I adjusted the idle//throttle cable to the manuel.

As I work on cars I know diagnostic is very hard over the internet or phone so I am tring to give all the info I can. The trans. seems fine no water does not seem to bind up. I will say that my throttle arm goes down to a 45 deg. before it starts to rev.

Any ideas would be great
Thank in advance

J.C.

P.S. If you ever need auto advice don't be afraid to ask.

 

[Chris1956]

Re: No Throttle on an 80hp merc?

JC - First check, engine off, motor cowling off, propeller removed. Put motor in gear and push throttle all the way forward. Do the carbs open fully? If not, the link and synch is out of adjustment. Second check, do the plugs look steam cleaned? if so, you may have water intrusion, especially in the lower cylinders.

Third check (idle timing event), looking down at top carb, advance throttle using cold start lever to the point when carb just starts to open. Remove plugs 2-4, tape them together so you can ground their casings and install their plug wires. Connect timing light to #1 plug, and crank motor. Timing should be 4-6 Degrees BTDC.

Fourth check, (max timing), open throttle fully, #2-4 plugs still removed and grounded. Crank motor by jumpering the starter solenoid. Check for max timing of 21 degrees BTDC

 

[tireman357]

Re: No Throttle on an 80hp merc?

JC - First check, engine off, motor cowling off, propeller removed. Put motor in gear and push throttle all the way forward. Do the carbs open fully? If not, the link and synch is out of adjustment. Second check, do the plugs look steam cleaned? if so, you may have water intrusion, especially in the lower cylinders.

Third check (idle timing event), looking down at top carb, advance throttle using cold start lever to the point when carb just starts to open. Remove plugs 2-4, tape them together so you can ground their casings and install their plug wires. Connect timing light to #1 plug, and crank motor. Timing should be 4-6 Degrees BTDC.

Fourth check, (max timing), open throttle fully, #2-4 plugs still removed and grounded. Crank motor by jumpering the starter solenoid. Check for max timing of 21 degrees BTDC

Hey thanks Just curious on why to take the prop off? The problem is under a load.

 

[Chris1956]

Re: No Throttle on an 80hp merc?

I recommend removing the prop when testing the timing, because there is a small chance the motor will start on one cylinder, and it will be in gear and you will be standing next to it with the timing light. We do not want any injuries.

 

[tireman357]

Re: No Throttle on an 80hp merc?

I recommend removing the prop when testing the timing, because there is a small chance the motor will start on one cylinder, and it will be in gear and you will be standing next to it with the timing light. We do not want any injuries.

Cool thanks. I will do all that and get back to you.