1988 force 125 wont tach over 4000 rpms

[Tinman78]

I have a 1988 Glastron Z-17 with a Force 125. I have done everything I can think of. New plugs, compression test, fixed trim pump, tried a 19p aluminum, 17p aluminum, and a 17p stainless prop, cleaned and link and synced the carbs, drained and cleaned fuel tank and filled with new fuel, checked static timing, checked for broken key under flywheel, checked for bent and wobbly shafts and changed fluid in lower unit, new water pump while I was in there, adjusted carb linkage for WOT. As soon as it stops raining I'm going to do the seafoam deep creep decarbon. I don't know what else I can do. The most I have gotten out of it was this morning I got 4200rpms and 31 mph on the GPS. That was with just me (150lbs) and no gear in the boat and just over 3/4 of a tank of fuel. Any new ideas?

 

[SkiDad]

seems like you have checked everything - have you check to see if your butterfly's are fully open with full throttle and engine off ? You speed sound right for the rpm you are getting but seems like it's just not opening up all the way.

 

[Tinman78]

Yea that was one of the first things I checked. When I first brought it out they were only opening halfway so I adjusted the linkage and did the link and sync instructions I found on here. Now they are about perfectly flat at WOT. Also I wanted to add that I had it on the hose earlier and put it in gear and quickly snapped it up to WOT and back and it tached right up to 5300 and back to idle again. I'm know that's a no-no but I wanted to find out if it would do it with no load whatsoever or if it would still stop at 4000. And it snaps right up there instantly on the muffs. I didn't get to do the seafoam deep creep decarbon today cuz it's pouring up here in maine so I'll have to do it tomorrow after work.

 

[tommarvin]

We made the mistake of adjusting the butterflies level, and didn't realize the butterflies were now open just a little at idle and the motor wouldn't idle down in neutral, stayed at 1500-2000 rpm.
If you cleaned the carbs,don't waist your time or money on the seafoam.
Can I ask you a question, we plane and the motor sounds best at 3000 rpm, we save a lot of fuel and extend our engine life., Why do you have to go WOT everywhere, can you be happy when the boat is planing at 3000 rpm?

 

[Tinman78]

Would be great if my boat planed at 3000 and stayed there but it doesn't. At 3000 I'm about 3/4 throttle and it's just barely starting to plane out. I figure if I can get it to the 4500-5500 range the manufacturer suggests then I could be at half throttle and still be planed out. And if I could get more out of it my cousin would appreciate not taking 2 min to get planed out and get him up on skis lol. Right now I have to got WOT for a minute just to get planed out then back down to 3/4. Any less then that and I'm sticking my neck out like a turtle to see in front of me...

 

[jerryjerry05]

Do a compression and spark test.
​Pull the plugs and see if they are all the same color?
Reving to 5500 at no load, even a 50 running on 1 cyl can do that.

Tom, your boat might work good at 3000 his obviously doesn't.
At 3000 my boat wallows and can almost stall.
At 34-3800 it runs but not as good as 42-4500.


Do a comp test and post a pic of the plugs.

 

[Tinman78]

150 to 155 lbs of compression in all cylinders. I just pulled the plugs to let the deep creep soak while I'm gone today and the number 3 plug is completely clean. The other three are normal dirty looking.

 

[Tinman78]

I'll do a spark test again in a bit when I get back home. Either number 3 isn't firing or its got a head gasket leak and steam cleaning that plug would be my guess. But it runs awfully smooth for it to not be firing

 

[SkiDad]

i vote that it is not firing - that would make sense of your RPM issues. check out outboardignition.com go to force page and then click year and model and look under power packs - there is a PDF that will help isolate.

 

[Tinman78]

Ok thank you. I called the boat junkyard guy near me and he has tons of force 125s and he said coils are $30. But I'll do all the testing and such to isolate it before I buy anything else lol

 

[Tinman78]

No spark at all on number 3 plug. And swapped plugs to eliminate bad plug

 

[Tinman78]

Swapped coils between 2 and 3 and still nothing on 3 but coil 3 works on coil 2s spot so sending wire or rectifier or stator?

 

[Tinman78]

Narrowed it down to a bad cdi module. Going to try and get one from the junkyard guy near me

 

[Tinman78]

Upon removing the cdi module I thought was bad I ended up finding that the trigger wire was broken inside the connector. Fixed the connection and now I have spark on all 4. Headed to the lake in hopes that this finally fixes my problem. For now at least lol. It is a hole in the water to which you pour money after all

 

[Tinman78]

So I'm on the lake now and I got 38 mph at 4800 rpms with 500lbs of people and gear and 20 gal of gas. Much better then before. And it planes off in seconds now and cruises at about 20 mph at 3000-3200 rpms.

 

[SkiDad]

that's great news ! and that speed is about right

 

[Tinman78]

Thanks for all the help

 

[jerryjerry05]

Your welcome.
​I had the same problem with one of mine.
Started as an infrequent miss, then one day a solid miss.
I kinda knew what was the problem.
Went and pulled the 1st trigger lead and it came out without any problem.

I changed ALLLLL the connectors.
Even stator leads..

 

[GA_Boater]

:thumb:

All part of the joy running older motors. Glad you got it, Tinman.

 

[Tinman78]

I love running older motors. My uncle has 3 that I've kept running for him for years now with help from this forum. This is my 3rd boat of my own and I am so glad this one turned out to be a good one. Now if I can get my trim problem fixed it will be about perfect