Out of Ideas 2

[Mark9740]

This is a sequel to my post last year. I bought a, '86 85Hp Force 1 1/2 years ago and put it on the water early last season. It ran great and I used it weekly to go fishing and cruising on the river. About halfway through the season though, my son had it out with his friends tubing and wakeboarding. They weren't paying attention and drained one of the tanks empty. After switching tanks and starting it up, it started missing and wouldn't idle without revving it in neutral and then quickly jamming it into gear. Since then, it hasn't run right. I cannot get the 3rd (bottom) cylinder to fire. Time after time (repair after repair) I took it on the water after that only to find the top two plugs carboned up but the bottom one shiny clean, and no water droplets on it.

Here is a list of what I have done to try and fix this problem:

- Checked compression 120 - 120 - 115
- Rebuilt the carbs twice
- Replaced the reed valves
- Replaced the head gasket
- Replaced the CD Module and Coil
- Verified the timing is correct (static)

I started it up on the muffs today after completing most of this during the winter. Same thing!! While it's running (roughly) I pull the bottom plug wire off and the engine speed / tempo never changes. I've got a good 1/2" spark jumping from the screwdriver to the plug. And when I'm done running it, there is a rainbow in the water running down the driveway from all of the unburned gas so I know it's getting fuel. I can run it on one plug at a time with the other two removed and grounded and the bottom cylinder one is the only one that won't run solo.

What else is left? I have compression, gas, timing and fire!!!! What am I missing here??

Thanks in adavnce for any help. I love iboats!

 

[trendsetter240]

Re: Out of Ideas 2

If I had the same situation I'd get a can of aeorosol carb cleaner, start the engine on the muffs and get it to idle, then spray the carb cleaner directly into the bottom carb throat.

If the engine speeds up then your carb is not providing enough fuel, if it bogs down and dies then the problem is not a lean condtion.

Now if the engine revs up when you spray the carb cleaner then you need to pull off that bottom carb, completely disassemble it, remove all jets and clean it. Use the aerosol cleaner to blow through each passage in the opposite direction that fuel would flow.

Once clean, check the fuel supply to that carb. With the fuel supply line to that carb disconnected, crank the motor and verify for fuel squirting out.

If you've got fuel then reassemble the carb and connect all lines checking each fuel line for any cracking and ensure an airtight seal on all connections. The try again!

P.S. Do not try to run the engine on carb cleaner alone as it has no lubrication. Only use it for a few seconds during the test I described above.

Hope that helps. Cheers.

 

[Mark9740]

Re: Out of Ideas 2

Hi Trendsetter,
Thanks for the idea. I can do that tomorrow. If it isn't a lean condition and it just bogs down, what's my next move?

 

[trendsetter240]

Re: Out of Ideas 2

Hi Trendsetter,
Thanks for the idea. I can do that tomorrow. If it isn't a lean condition and it just bogs down, what's my next move?

If it bogs down then it means that carb+cylinder is working. Actually given that it makes no difference when you pull that bottom plug wire off I doubt it will bog down.

It will either rev up or make no change. So in the case it makes no change then the problem is in reeds, compression or spark. I think it is likely you will find a lean condition on that bottom carb.

 

[pnwboat]

Re: Out of Ideas 2

To verify the electrical/ignition system, you can use this site to measure the windings on the stator and trigger using an ohm meter.

http://www.boatpartstore.com/page38.asp

If they check out OK, double check the crimp connections on the spade lug connectors from the trigger and stator on the terminal block. If there is a small piece of heat shrink tubing right covering the wire where it is crimped to the spade lug connector, remove it to verify that all the strands of wire are intact. I've had several instances where there was only one strand of wire left. It measured OK with the ohm meter, but apparently it would not pass enough of a signal to trigger the CD module.

One other thing. There is a blocking diode in the kill circuit of the CD module. The module with the bad diode will function just fine, however, it will affect the other CD module making a good module appear to be bad. This may be the case with your motor. To check, disconnect the kill wire (white wire) from the CD module for #1 and #2 cylinders. See trouble-shootings tips below regarding this.

http://www.boatpartstore.com/page6.asp

NOTE: When you disconnect the white kill wire and start the motor, the motor may not shut off when you turn the ignition key off. No need to panic...to stop the motor the easiest thing to do is to hit the choke and flood the motor to stop it. You could also touch the white wire to ground. This kills the signal to fire CD module. This is how the ignition key turns the motor off. It shorts the white wire to ground when you turn it to the off position.

 

[Mark9740]

Re: Out of Ideas 2

PNWBoats-
I appreciate your insight and ideas. I am not an electrical analysis type guy. I know how to use a multimeter for basic functions but am lost when it comes to checking the "high side" or "low side" of a stator or trigger. I tried spraying the carb cleaner in the bottom cylinder while running it with no change. Gas was still running down the driveway with the water from the muffs. I also disconnected both white (kill) wires and no change...same thing. I checked the spark of all three plug wires and they all appear to be the same length when held from the plug with a screwdriver jumping a good 1/2 inch. A couple of times when I tried starting it, it backfired. It did that a lot toward the end of last season when I was trying to get it moving.

I have a question: Could the timing for the top two cylinders be fine and the bottom one messed up? If so, would the most likely culprit be the trigger? I called a local repair guy and he told me to scrap it because Forces are junk. I certainly won't be asking for his opinion again anytime soon but I am running out of ideas and $.

Thanks again for your help.

 

[pnwboat]

Re: Out of Ideas 2

It's possible that the trigger could be causing the problem, or it could be the stator. Could get pretty expensive to swap without checking them.

One thing I would agree on, don't take the advice of the local repair guy. When I encounter anyone with that attitude that has a Force motor they're getting rid of, I wholeheartedly agree with them...on the outside. I offer a nominal fee to take it off they're hands to dispose of it, and jump for joy...on the inside, as I carry it off to my shop.

Anyways, back to your problem. Did you try pulling the plug wires off at an idle to see what affect it had on the idle speed?

Also double check the spade lug connectors on the terminal block where the CD modules, trigger, and stator are connected. If they have a small piece of heat shrink tubing covering the actual crimp connection take it off to verify that all the strands of wire are intact. I would concentrate on the connections for the 2nd CD module for #3 cylinder. I've seen several instances where there was only one stand of wire left. After replacing the spade lug connector, the ignition system began to work properly.

 

[Mark9740]

Re: Out of Ideas 2

I did pull off the plug wires. When I pull off 1 or 2 it stumbles and shiuts down. On #3, no change when I remove the plug wire even though the spark keeps jumping. As far as the wiring for the CD Module goes that must be the problem. I have to confess that I was so happy to get the new CD Module (used) last summer that I didn't take the time to put in spade connections. The wires had been cut on both ends so I ended up splicing (twisting) them together and covering with electrical tape. You think spade connections could make that much of a difference?

 

[pnwboat]

Re: Out of Ideas 2

Only if the wires are not making good connection. I would also begin to suspect that the used CD Module you got may be weak/bad.

Here's another thing you can try to verify the CD module. Make sure you write down where the wires go on a piece of paper before you start disconnecting them. Both CD modules have the ability to fire two coils. #1 CD module fires #1 & #2 coils. #2 CD module fires #3 coil. #2 CD module has a portion that is not used. The unused wires from #2 CD module are attached to the terminal block, but there are no trigger or stator wires going to those connections. Move the stator and trigger wires for #3 cylinder to the unused connections on #2 CD module. Use the color code from #1 CD module as a guide. Also remember to switch the barrel connector that goes between the CD module and the coil itself.

I'm not sure if I'm clear but hopefully you kind of get the idea. You can also try this out with your original CD module if you think it's necessary just to double check. I know it's a pain in the you know what, but it may be worth it in the end.

 

[Mark9740]

Re: Out of Ideas 2

I think I follow what you're saying. I'm heading out to NY for work this week so hopefully I'll have a chance next weekend to take another crack at it. I will let you know what I find. Thanks.

 

[dougl58]

Re: Out of Ideas 2

Running out of gas will not cause your electrical to go bad. If the third or bottom cylinder is not firing it may be flooding. Running out of gas may have caused the fuel pump diaphragm to rupture. If it is it can leak fuel down to the bottom cylinder.

Pull the fuel pump off (easy task) on the side of the motor. 6 screws where you see fuel lines. If the rubber diaphragm is ruptured or split get a new one. You may not even need to replace the gasket.

 

[jerryjerry05]

Re: Out of Ideas 2

First check the fuel pump diafram. Then do another compression test.
I had a motor have good compression but it still was leaking.The head developed a low/burnt spot and leaked into the cylinder.J

 

[Mark9740]

Re: Out of Ideas 2

Dougl58,
Thanks for the idea. I had never considered the fact that it may be ruptured. I'm getting a lot of gas coming out with the exhaust while it's running on the muffs. I'll make this my first priority when I get back to work on it. I think I needed to replace the CD Module anyway. The spark on the third cylinder was non-existent after my son had it out...probably a coincidence. I'll let you know what happens.

 

[Mark9740]

Re: Out of Ideas 2

First check the fuel pump diafram. Then do another compression test.
I had a motor have good compression but it still was leaking.The head developed a low/burnt spot and leaked into the cylinder.J

Jerryjerry05,
What do you mean by "it was still leaking?" The fuel or the compression? And what leaked into the cylinder? the fuel?

Thanks. I'm just trying to understand. This is my first boat motor so it's been a heck of a learning curve.

 

[Mark9740]

Re: Out of Ideas 2

Dougl58,
You're the man!! I checked the fuel pump diaphram and it had a tiny split about 3/16" long. Great call! I replaced it and she screamed to life. Thanks a bunch! I'll have her in the water here in the next few weeks. I appreciate your help