85/89 force 85 difference

[Homebrew72]

I currently have an 1989 force 85 that I am having some issues with. I came across an 85 force 85. Just wondering what the difference in these motors are?

 

[SkiDad]

not much - i think it's mostly the wiring connector (snap type versus terminal) and paint color.

 

[Jiggz]

What is the issue with the 89-85HP?

 

[Homebrew72]

bunch of things wrong/going wrong. compression is at 120/110/120 wont run above idle think the carbs need to be rebuilt. Guy is only asking 250 for the 85 motor just wondering if it would be worth getting it rather than dumping a bunch of money on mine.

 

[Jiggz]

Have you checked the compression on the 85-85HP motor? Is it running? Smoothly idling and at WOT? If it's not mounted on a boat and cannot test run it, at least you should be able to get compression readings. I seriously doubt if that motor has NO issues. No compression readings for me means no deal.

As for the 89-85HP, the compression numbers may not be perfect but they are not bad either. The lower number on #2 cylinder is probably due to a torn diaphragm on the fuel pump or stuck fuel pump check valve. Thus this could also be the cause of rough idling or lack of high rpm at WOT. You can try installing a clear fuel filter (Fram G2 from Walmart for less than $5 will do) between the fuel pump outlet and the carb's inlet to troubleshoot the fuel delivery system. The clear fuel filter should stay at least 1/2~3/4 full at all times especially at WOT. If not you have fuel delivery problem. While in the water testing, when the clear filter gets empty try pumping the primer bulb and see if that will fill it up . . . if it does then you most likely have a fuel pump problem. But if the primer bulb stays collapse then you most likely have a problem with the pick up, tank vent or faulty check valves on your primer bulb.

The preceding troubleshooting only costs less than $5. That shouldn't be too much to spend to try to fix and learn at the same time. I say try it first.

 

[Homebrew72]

The guy said the 85 was running last season, hasn't tried it this year. I'd do a compression test before buying it for sure.

As for my motor I do have a clear filter between the bulb and the pump. It's stays about half full and the bulb stays full as well. If I add a filter after the pump is that going to cause low fuel pressure due to running two filters?

 

[Jiggz]

Between the bulb and the pump is just an absolute NO NO. Need to move that filter between the pump and the carbs. As for the seller saying it was running perfectly last season . . . that is almost a standard line from all sellers.

 

[Homebrew72]

Ok so I rebuilt the fuel pump and added an inline filter between the pump and carbs. Started it up and still have a miss going on at idle not so much at fast idle. I was watching the fuel move through the filter after the carbs, every time the engine would miss you could see a surge of fuel go into the filter. The filter was completely full of fuel. The filter between the bulb and pump was less than half. Another "issue" I saw was I had the lower end in a tub of water. After a few minutes of running the water was freckled with oil droplets.

 

[Frank Acampora]

Oil in a tub of water is a given. You would be surprised at just how much the engine discards. That is why most two strokes are banned fro lakes out west. The fuel pump has brass button valves and a rubber diaphragm that can shed pieces. SO the last thing you want to do to gas before you burn it is filter it. Thus a filter BETWEEN the fuel pump and carbs is the best location. With it you do not need another filter at the tank or bulb and you can even remove the screen at the fuel pump for less restricted flow.

Of course, if you do have a problem with gas a filter/water separator mounted on the splash well is good.

 

[Jiggz]

As mentioned, the oil in the water as a part of the exhaust is norm. What is not norm is having an inline filter before the fuel pump. Now that you know the filter between the fuel pump and the carbs is staying full and you are still having miss at idle, the next step is to check for spark in each cylinder using an inline spark tester (costs approx $10 from auto stores). But before doing this you need to make sure the air fuel mixture screws on each carbs are set to 1 1/8~ 1 1/4 turn from slightly seated. And then the next thing is to make sure the idle rpm in neutral on earmuffs should be at least 1000~1100 RPM. If the engine is still missing at idle (remember when you rev up the engine you might think the misfire is gone but it's actually just being masked by the high noise and high rpm), then do the plug wire pull test to find out which cylinder is misfiring or not firing.

With the engine idling, pull one plug wire at a time (do it quickly to avoid damage to CD modules) while listening to changes in engine RPM. If the engine rpm decreases then it means that cylinder is firing. If there is no change in engine rpm that means that cylinder is either not firing or misfiring.

 

[Homebrew72]

Would a kinked vent like cause similar issues?

 

[Homebrew72]

Pulled the plug wires while it was running. All three cylinders made a change in engine sound when i pulled the plugs. #1 made the biggest difference in sound and stumble

 

[Jiggz]

That means none of the cylinders is misfiring. Are you sure it is a misfiring and not just too low of an idle setting. Usually, with this 85hp the idle speed while on earmuffs and in neutral should be around 1000~1100 rpm. Double check also the fuel air mixture settings make sure it is at least 1 1/8~1 1/4 for each carb. If you have an inline spark tester test #2 and #3 cylinders for consistency of spark. If there is inconsistency then there could be misfiring due to electrical problems. If you do not have an inline spark tester, the next best tool is a timing light. Deflect the timing light's strobe on a dark sheet of paper and watch for consistencies in sparks.

 

[Homebrew72]

I pulled the plugs to check the timing, 1&2 where clean, 3 was black. I adjusted the timining. Engine seems to run a little better, the miss/stumble it had before is much less noticeable now. Engine is still randomly stalling where it will be running fine then immediately stop.

 

[Jiggz]

The spark consistency test is important to find out if the misfires are electrical in nature or not. If sparks are NOT consistent double check all the trigger wires for integrity. If sparks ARE consistent, do the spray test to see if it is carburetion problem.

 

[Homebrew72]

I got it on the water today, had an issue with it when throttling up. If I eased into it it would stall, if I gunned it, it would come up on plane ok. Aside from that I was topping out at 28 with just me in the boat. I couldn't tell what the pitch was, there are no markings visible. I have a spare prop that is a 17 pitch. That should help me get the speed up right?

 

[Jiggz]

Do you happen to have a tach? What is the top rpm? What is the idle rpm in neutral? How about idle rpm in gear? I don't believe it is the prop but you can try changing it with a known prop pitch to get that out of the equation. I'm still wondering if you have removed the filter between the pump and the bulb. Double visual checked all trigger wires? Would it be possible to make a short u-tube video so we can see how it idles?

 

[Homebrew72]

What do you mean by trigger wires? I haven't removed the second filter yet and no tach. I put the 17p prop on and put the trim lock bar in the second hole, today I was running it in the first one. Hoping getting the bow out of the water a little will help. I'll try to get some video tomorrow.

 

[Jiggz]

Trigger wires are those small electrical wires coming off the trigger unit located under the flywheel. They come in pairs of two wires with a total set of 3. The trigger unit provides the signal for the CDM when to discharge its capacitor to feed high voltage electricity to the coils hence to the spark plugs to fire the cylinders. Trigger wires are totally insulated and should not be touching ground but should have good connections to the terminal board connecting them to the CD modules.

 

[Homebrew72]

back it the water yesterday, in less than favorable conditions I was able to hit 34mph. It was rather windy and choppy out, if it was calm out I think it'd of been pushing 40 which is about max for these motors right?