89 Force 125 won’t rev and bucks

[Danwv100]

Bought boat , took on 2 trips with no issues. Bayliner Trophy bass. All of the sudden during the third trip out it started bucking while running around cruising 3500rpm, then kind of suring with an increase or decrease of 2-400 rpm. Throttled down and let it idle for a second, accelerated to get on plane and boat would not run over about 3200rpm and has a constant surge. Won’t get on plane, only runs about 12 mph. Idles smooth and runs good until WOT and it hits the wall of about 3200 rpm and won’t rev out. Replaced all fuel lines, and rebuilt fuel pump, replaced spark plugs. Cycling water good, doesnt burn your hand and plenty of it. Put back in water and no change. Any ideas, what next?

 

[hoosier boater 1960]

I have the same motor,when mine did that several different times,it was some of the trigger wires broke,where they attach to the bus bar.Hope this helps.

 

[Nordin]

First of all check compression and spark at all 4 cylinders.
Compression should be 140-150PSI, but lower numbers (about 110-135PSI) will be okey, BUT it is important that the numbers are pretty equal.
Not more then 10-15% in different.

 

[jerryjerry05]

Spark check each cylinder as you drive in the water.
Can be hard to do but it sounds like your dropping a cylinder or the exhaust is leaking into the hood??
Hoosier mentioned the trigger wires. The 89 125 trigger, the wires are real thin and break easily under the shrink wrap at the connector.
Do the tug test on each wire, don't pull too hard.
If 1 is loose?? then it's a good idea to replace all of them..
Take pics as you go along.
Do the starting fluid test too, start the motor and then spray starting fluid around the "intake side" (under the carbs, around the 4 port covers) if this makes any difference, then your sucking air and a gaskets gone bad somewhere???

 

[Danwv100]

Thank you for all of the advice. I did already do a compression test and read 125-135. Dropping a cylinder is kind of what I thought. From the reading I’ve done on the forum I’m expecting trigger wires. I was worried about it potentially being a power pack. I found a wiring diagram and will the Take a look at triggers after work, depending on the weather will take it to the river and try to spark check. I’m guessing you mean with a timing light?

 

[jerryjerry05]

I use a small tester.
Do the starting fluid test, this can solve a lot with very little work.