1984 75 HP Mercury outboard motor Problem?

Question

I have a 1984 75 HP Mercury outboard motor, it runs good when it’s out of the water, BUT when there is a load behind it, in the water is bogs down and dies. I’ve had the carbs rebuilt, fuel lines replaced, fuel tanks cleaned, filters added, stator replaced and the certified mercury mechanic spent 5 hours trouble shooting Saturday and can’t find the problem. Does anyone have any suggestions?

Answer 1

Make sure your trigger is advancing your timing all the way. I assume your compression is good (all within ten pounds of each other).It sounds like your synch and link might be off. Ask your certified mechanic if he checked all the linkages and timing advance.

Answer 2

what, Tennessee bass don't bite in the winter? If you're going to be fishing this winter (I sure as heck am), just do this: tilt the motor fully down for a few minutes after each use, to make sure all the water drains from the powerhead, and change the gear oil, just in case you had some water intrusion (so it won't crack the gearcase by freezing). If you do decide to winterize, spray fogging oil through the carb throats with the motor idling, until it chokes 'em out.

Answer 3

Check the vent on the fuel tank>Take the primer bulb an squeeze till hard keep squeezing while running if works fuel pump bad or lousing vacuum inside Eng as the crankshaft seals are leaking inside internal> ele fuel pump needed >

Answer 4

not much of a "certified mechanic" if you ask me. you need 100# compression on 4, clean carbs. with correct jets, timing set, fire on 4, and clean oil/gas mix. if all that's good, pull the intake and check the reeds.

Answer 5

Pull the plugs and see if all the plugs are firing the same. I had head gasket fail and you described my symptoms exactly. The head gasket is simple to replace.

Answer 6

did you mech check voltage output? coils,spark(color),pwr pack? Why 5 hrs? I agree with checking sink&link ,why were filters added?