1988 Froce 85HP 856y8B Won't Start.

[philForce85]

I bought this boat last summer and the guy said he had some issues with the key switch but he started it to demo it and it did run.

so I had a look and the key switch was bad for sure. I picked up an after market switch and it is a bit different.

The original switch had an option to push the key when cranking to activat the choke so I put a switch from the ignition terminal ( Yellow with red stripe) so I turn the key to the cranking position and if the switch is on it chokes too.

Nowit cranks ok but it wont' start. I found wiring info that shows how the wires go to the switch but nothing that actually shows how the switch works.

the wires back at the terminal block on the motor are as such:

1 - starter - yellow
2 - regulator rectifier (tach) purple
3 - CO-unit - white
4 - choke - green
5 - orange (heat sensor for buzzer)
6 - Red wire to bat +
7- CO unit blue
8 - ground - black

wire 7 isn't actually present on the terminal block, that and the orange aren't going anywhere but shouldn't be needed to start the motor, later I can play with the heat sensor buzzer thing but I'd like to start it.


looking at the back of the original key switch I have 6 terminals
going clockwise starting at the hot wire

1 - red - hot
2 - white CO Unit - marked M on old key
3 - blue - CO Unit - marked M on old key
4 - this terminal not use ( even on the schematic)
4 - yellow - starter motor (solenoid)
5 - green - choke

so I need the red, that\s power, if I connect that to the green, I should get choke. I can do that through a separate switch..
Red to yellow makes the motor crank.

All that is left is the white and the blue and both go to C0 -unit it is marked M for magneto I guess on the back of the key. If it were an old car it would just make the coil hot but these two wires have me stumped.

Can I assume that these wires, if joined will act as a kill switch? or should one of those see power in order for the ignition to get a spark?

It seems like I have it cranking but not firing and I suspect the ignition - no spark (hard to check myself) I opened the old switch but the switch wasn't in good enough shape to figure out how those last two wires should be influenced by the key switch.

Obviously I should order a new key switch but I think if I could just understand how it should work I should be able to wire around the issue that my off the shelf key is a bit different.

if I could just get this one last piece of the puzzle solved I would have a much better weekend. I have been fixing other issues on it for a week solid ( i did some fiberglass patching rebuilt surge brake system, etc) I really want to take it for a spin. Any help would be greatly appreciated.

 

[pnwboat]

The White and Blue wires on the ignition switch are used to kill the ignition system when you turn the key to the OFF position. The Blue wire normally goes to ground. The White wire on the back of the ignition switch normally comes from the white wires on the 2 CD modules. When you turn the ignition switch to the OFF position, the White and Blue wires are shorted together. This "grounds" the ignition signal on the CD Modules and kills the ignition system.

If you check the resistance between the White wire on the CD Modules and ground, and it indicates a short, then you will will not see any spark at the plugs. If it reads "open", then you should see spark. Under normal operating conditions, you should be able to toggle the "open" and "shorted" readings when measuring resistance between the White wire and ground with your meter by turning the ignition key from the "ON" position to the "OFF" position.

 

[philForce85]

Thank you very much for the hep with this Captain. as it were I took the boat out to my brothers place, we cranked it together and it did have spark. I fixed up the other necessary wiring just to test it switch for choke , switch for kill just used the keyswitch for ignition and power to the choke switch. it ran. I will recheck it as per your notes but it sounds like that's what I did.

I took the boat up to our summer place for a test, it seemed to run pretty good until we got a mile or so away , then it started running at about 1/3 power, then after 10 mins when we nearly got back and it quit , seemed to have used a lot of gas for the amount of time I had it going.

The second and third day we had similar results. it seems to have power for a while, then it bogs out and runs at half speed, then quits. I had trouble starting it , it would start on high idle but if I tried to slow down it would die when it went into gear , I was able to assist the throttle manually a bit to keep it running through that neutral position.

Maybe a float bowl gets stuck and floods it, or something? someone mentioned that the gas can might not be able to get air? I am just using a plastic 5 gal can for now to make sure fuel is clean. It isn't overheating, sounds pretty normal. I haven't taken the fuel filter on the motor apart and I heard it has a few bits to it so maybe I can find a drawing first or take pictures. Maybe jets are plugged in the carbs but it wouldn't quite explain why it runs better intermittently.

The boat was really plowing the water and the tilt switch is bad so I just tried it from the battery. it seems to slip down on it's own especially when raised right up.
I suspect that could be a bad check valve or more likely bad seals allowing bypassing of fluid within the cylinder. Ill need to tend to this as well. For now at least it runs and it seems like the accumulation of little issues could be fixed. the fact that it can make power and sounds mechanically ok is promising, but I am not out of the water yet, ;-) it won't plane with the motor set like that, just makes a huge wake. maybe I could prop the motor with something. I wonder what the factory jig that is supposed to hold the motor up when towing looks like?

so many questions and some progress, thank you for the help.

 

[pnwboat]

Well at least it sound like you're making some progress. You got it to start and run. Next thing I would tackle is the bogging down.

If you haven't already done so, you should do a compression test just to see what shape the cylinders are in. Hopefully you should see a minimum of 120lbs.

Check the spark when it's bogging down. Need to have a good strong "snappy" spark on all 3 cylinders. If you have a good strong spark on all 3 cylinders, need to check the fuel delivery.

You should have a primer bulb. It should get pretty firm after you squeeze it 4 or 5 times. If it doesn't get firm and you start to see gas coming out of the fuel bowl vent hole on the carb(s), then the needle valve is either bad, or debris is preventing the needle valve from closing, or the float height is not set correctly.

Make sure the fuel pump diaphragm is not torn or has a hole in it and is not hard. It should be soft and flexible. If the diaphragm is leaking, it can dump excess fuel into the by-pass port and flood the engine. You should install an in-line fuel filter between the fuel pump and the carburetors.

The Tilt/Trim not holding the engine up should not prevent it from getting on plane if the motor is running correctly. The Tilt/Trim will maximize the efficiency of the motor by minimizing the drag between the hull and the water. What size/model boat do you have it mounted on?

Here is a post by Jigzz one of the members on the forum to determine what is causing the leak down.
http://forums.iboats.com/forum/engi...11-information-on-tilt-and-trim-on-a-force-87

There some "O" ring seals on the Tilt and Trim cylinders that could be bad. Here is a re-build kit to address that.
http://www.ebay.com/itm/Rebuild-kit..._Accessories_Gear&hash=item339317db11&vxp=mtr

If that's not the problem, then most likely the seal(s) in the check valves in the valve body are bad. Here is a post that has a lot of good info concerning the valve body check valves. Probably no need to take the valve body apart, just remove the two check valves which in your case are probably held in with circlips.
http://forums.iboats.com/forum/engi...tboards/603043-tilt-trim-force-50hp-slow-leak

 

[philForce85]

thank you so much this is all such great info. I have the motor on a 19 foot fiberform boat and I had four people in the boat I'd say combined weight of 600lbs so not a light load. It seemed to kind of plough downward though and the water rolled off the sides, It seemed to be putting out some power as it did go and made a huge wake but I really needed to get the nose up and it couldn't climb up. The previous owner put a sharks fin thing on the motor, I am not exactly sure what that was supposed to improve..Ill check what I am able to over the weekend. The post made perfect sense and it really helped and thank you for taking the time to help me I really appreciate it. I have a good list of things to look into now.

 

[pnwboat]

The shark fin (I'm assuming this is the horizontal fin mounted on the lower unit?) is supposed to keep the bow down and prevent porpoising for a smoother ride. Sometimes they help, sometimes they don't. Depends on your particular boat. I would take it off for the time being. After you get things sorted out, you can put it back on and see if you like it.

 

[philForce85]

I changed the fuel pump diaphram and the hose between the fuel pump and the carbs and tested the boat. I'll go up again with more tools next time and test the spark, compression etc, The problems were similar. It runs quite well when first started , then after about 15 mins at higher throttle it seems to start getting way too righ a fuel mixtureor for some reason running at low power. i think, even when it bogs the engine seems to run constantly without missing, but even at full throttle it feels like 1/4 throttle. I expected it to use a lot of gas but it seems to use more than it should.
I unbolted the tilt/trim stuff and ordered the rebuild kit for the cylinders. It seemed like the adjustment was there to get the tilt right but they do leak down ,or as noted , could be an issue with the pump. Perhaps I need a kit for the pump too?

can I also do a vacuum gauge check of the crankcase pressure?
could this be a symptom of an issue with the temperature sensor? it doesn't seem to be overheathing , actually the head felt surprisingly cold.
Phil.

 

[philForce85]

I changed the fuel pump diaphram and the hose between the fuel pump and the carbs and tested the boat. I'll go up again with more tools next time and test the spark, compression etc, The problems were similar. It runs quite well when first started , then after about 15 mins at higher throttle it seems to start getting way too much fuel, or for some reason running at low power..When it bogs the engine seems to run constantly without missing, but even at full throttle it feels like 1/4 throttle. I expected it to use a lot of gas but it seems to use more than it should.
I unbolted the tilt/trim stuff and ordered the rebuild kit for the cylinders. It seemed like the adjustment was there to get the tilt right but they do leak down ,or as noted , could be an issue with the pump. Perhaps I need a kit for the pump too?

can I also do a vacuum gauge check of the crankcase pressure?
could this be a symptom of an issue with the temperature sensor? it doesn't seem to be overheathing , actually the head felt surprisingly cold.
Phil.

 

[pnwboat]

The low power issue could be caused by ignition, fuel or mechanical problems. Need to perform a compression check before you get too involved. If you have a bad cylinder(s), worse case scenario you may be looking at a re-build.

Not sure a vacuum gauge would be of much benefit as the crankcase pressure is not stable, it's a pulse so it's kind of hard to read on a gauge. Temperature sensor does not affect the way the motors runs. All it does is trigger the overheat buzzer, if you've got one. If the head feels cold after running for some time, then the motor is not running properly.

 

[philForce85]

Thankyou I will check the compression when I am up where the boat is next. there may be a wait in between. Meanwhile I will go ahead and rebuild the trim and lift cylinders. If it does need a rebuild I can probably handle it as I have rebuilt a few car engines but never a two stroke. Hopefully parts are available but I'lll check compression before I get ahead of myself with that. there is an extra set of coils that came with the boat so they had been swaping them around at some point.Thanks for the info on overheat buzzer, so that isn;t the cause, would a bad thermostat be suspect?