Baffled and driven to drink- 1999 Force 75 misfire?

[lawyeratlarge]

I purchased a used pontoon boat 2 years ago for the wife- it is HER boat so now you know the importance of my problem. boat would not start without agressive cold start application- ran rough as a cob, would not idle. Flywheel had tossed part one of the magnets. Purchased a used fly wheel, stator and trigger assembly as instructed by the mechanic. When the boat was in the shop I purchased another 1999 75 hp force with a hole in the block for the spare parts.

The motor ran fine for a couple days and then same type problem occured. My mechanic tells me the trigger assembly "sh*t the bed" again. Long story shortened- after 6 more trigger assemblies another fly wheel, another stator, a full set of firing coils, and new rectifer, fuel pump (all used) and the wiring harnass off the blown engine, it will not idle. Mechanic says it is 'firing behind time".

I had the reed values replaced last year and a new trigger assembly installed when the same type problem occurred. You must use the cold start, it will not idle, lots of unburned fuel. He says it is in the ignition system but after all that above I am doubtful of that.

Help I am running out of vodka!

 

[lawyeratlarge]

Re: Baffled and driven to drink- 1999 Force 75 misfire?

Some additional and possibly pertinent information concerning the motor.-

Compression readings are between 145 lbs and 150 lbs on all three cylinders.
There are two fuels filter on the fuel line- a water filter and a clear one at the fuel pump.
The fuel is clean and fresh.
Carbs have been cleaned and adjusted.

When I took the boat to the shop, he changed the trigger assembly and started the motor with a remote because I forgot to take the key, it ran fine. We attached the boat wiring harnass and started it with the key and the problem started again. He said the trigger assembly had blown. We then replaced the boat harnass, isolated the motor from the rest of the electrical system and started the part replacements.

Then the fun started as stated my first post. He now says there are multiple problems with the motor. I like my mechanic and trust him but he is admiitedly baffled. I am thinking he now has developed tunnel vision focusing on the electronics and a fresh perspective may help us both.

 

[roscoe]

Re: Baffled and driven to drink- 1999 Force 75 misfire?

Welcome to iboats. Sorry to meet under these circumstances.

I like my mechanic and trust him but he is admiitedly baffled. I am thinking he now has developed tunnel vision focusing on the electronics and a fresh perspective may help us both.

And he likes you too.

Tunnel vision, the tunnel he sees leads straight to your bank account.

You could have bought several motors for what you've spent on parts.

Where has he set the timing to?

How many pounds is he torquing the flywheel to?

A trigger failure is a rare parts failure as these engines go.

Does this guy have a clue?

Is this a dealership? A full time service department?

Almost unbelievable.

 

[lawyeratlarge]

Re: Baffled and driven to drink- 1999 Force 75 misfire?

Roscoe,

Shade tree mechanic. the motor will start and but runs rough at about 2,000 and above. Never smooths out and stumbles and dies if you drop the revs below 1500.

 

[kywings]

Re: Baffled and driven to drink- 1999 Force 75 misfire?

lawyeratlarge, I have the same motor except a 1998. Also have same issues. I'm convinced I can fix it and have a good motor. Just frustrated. Dont trust anyone local. Boat grew up here and I think the local guys have performed substandard maintenance from the little things I have seen. I have owned it for a year. I have a couple questions.

First, you mentioned a magnet. The nut on my starter likes to fall off. When I went fishing for it I found it attached to a magnet laying under the motor. I was stumped as to where this came from and the starter is sealed. So since I'm new to the out board motor are there magnets in the flywheel? And where are they located?

Second, when mine misses it is at idle or low RPMs and usually stalls. Then wont start unless I pump primer bulb 3 times. Have you replaced the fuel pump diaphragm? I'm thinking of doing that next. Running over 2000 RPMs runs smooth and plugs are new an appear to be operating ok. I have a hard time thinking it is electrical.

I lost about 600 RPMs just messing with it. Thats a mystery at the moment

 

[lawyeratlarge]

Re: Baffled and driven to drink- 1999 Force 75 misfire?

lawyeratlarge, I have the same motor except a 1998. Also have same issues. I'm convinced I can fix it and have a good motor. Just frustrated. Dont trust anyone local. Boat grew up here and I think the local guys have performed substandard maintenance from the little things I have seen. I have owned it for a year. I have a couple questions.

First, you mentioned a magnet. The nut on my starter likes to fall off. When I went fishing for it I found it attached to a magnet laying under the motor. I was stumped as to where this came from and the starter is sealed. So since I'm new to the out board motor are there magnets in the flywheel? And where are they located?

Second, when mine misses it is at idle or low RPMs and usually stalls. Then wont start unless I pump primer bulb 3 times. Have you replaced the fuel pump diaphragm? I'm thinking of doing that next. Running over 2000 RPMs runs smooth and plugs are new an appear to be operating ok. I have a hard time thinking it is electrical.

I lost about 600 RPMs just messing with it. Thats a mystery at the moment

There are 6 magnets attached to the underside of the flywheel. The magnets along with the stator generate the electrical current used by the motor and charge the battery(ies)

 

[lawyeratlarge]

Welcome to iboats. Sorry to meet under these circumstances.



And he likes you too.

Tunnel vision, the tunnel he sees leads straight to your bank account.

You could have bought several motors for what you've spent on parts.

Where has he set the timing to?

How many pounds is he torquing the flywheel to?

A trigger failure is a rare parts failure as these engines go.

Does this guy have a clue?

Is this a dealership? A full time service department?

Almost unbelievable.

He is a retired mechanic and puts the flywheel on with an impact. I ask him about the timing and he told me with the CMD ignition the timing was set at 5,500 RPM and it will is stuttering and missing to bad to get there.

When the motor is running you can pull # 1 and #2 plug wires off - one at the time and then replacing it- and there is little change in the sound or stumbling of the the motor. Pull #3 and it will almost shuts down. we have changed all the CDMs.

At this point in time he says he has no clue! as I said we have changed the entire igniton system. What puzzles me is that the boat ran fine last use, we got home late (midnight) so decided flush in the morning and then all this started after sitting overnight in the driveway.

We love our boat but Iam almost tothe point of jacking in up and putting a yamaha on it

 

[kywings]

Re: Baffled and driven to drink- 1999 Force 75 misfire?

Have you had any luck with yours??? I m going to rebuild the fuel pump and look at this magnet situation Saturday. Local NAPA can get parts over night so we'll see. I have a sneaky suspicion the missing magnet causes the hard miss at low RPM. Have no idea what caused the loss of RPM. I'm hoping fuel.

 

[lawyeratlarge]

Re: Baffled and driven to drink- 1999 Force 75 misfire?

I appreciate all the responses to my post. Finally got the "Happy Ours" back on the water yesterday just in time to see the Blue Angels from Pensacola Sound.

After MUCH trial and error, and new trigger assembly with the correct part number, the motor was running better but still firing out of time. As a last ditch attempt, just before conversion to a marine habitat reef, we decided to change flywheels, we had 2. When we took the flywheel off and compared it with the spare we checked the part numbers. Both looked the same, 97 teeth etc. EXCEPT for the last 2 characters. The one we removed had C4 on the end and the spare had C3.

We put the C3 flywheel on, adjusted the timing and carburators, and she runs sweet as honey.

Assumption here- C4 is for a 4 cylinder and C3 is for a three cylinder.

The moral to the story- Always check the part numbers first when replacing, especially with used parts. Looking the same does not mean the same.

 

[roscoe]

Re: Baffled and driven to drink- 1999 Force 75 misfire?

Glad you are making progress .

Make sure that the flywheel is torqued to 125 ft-lbs, or it will shear the key. Doubt you can get that with an impact gun.