1998 Force 75

[1uz4x4]

Hello,
I've been tryting to get rid of a miss that gets pretty bad around 3000rpm and up. Motor will only get up to 4850 rpm, and has a slight shake. I've bought a book and checked diodes and resistance on coils, also checked stator per instructions in book. Just tonight I found the two yellow wires from the regulator/rectifier were burnt and brown at the connectors. I fixed the connections and checked voltage at battery, 14 v at idle. I also checked it with my voltmeter by the book. I do not have a DVA meter, may have to borrow one from one of our electricions at work. Any ideas on what I need to check next. Motor is on a 21' suntracker deck boat with a 12 x 10.5 prop. Jumps out of the hole, seems to have plenty of power on the bottom end.
Thanks in advance for any help.

 

[1uz4x4]

Re: 1998 Force 75

Also,
I have checked the plugs, put in new ones, they look fine, have done compression check, (1)135, (2)140, (3)135. Replaced all fuel lines, and rebuilt fuel pump.

 

[jerryjerry05]

Re: 1998 Force 75

Check for water in the fuel.
Clean the carb.
While it's off look at the reeds.
Plugs all burning the same?
Not sure the regulator would make it miss??

 

[1uz4x4]

Re: 1998 Force 75

Thanks Jerry,
I'll pull the carb and clean it tonight.
Hope that's what it is, I'm getting ready to throw parts at the ignition side.
No water in fuel, plugs all look the same, nothing stands out.
Guess I had it in my head it is a firing miss not a carb issue.
I just got the boat about a month ago, sure i'll find other stuff wrong with it before it's over.

 

[TwoFish]

Re: 1998 Force 75

I have the same motor as you. Had it for 3? years. It took me about 6 months to get it sorted out in the beginning. Partly my lack of knowledge and partly things needing to be bought up to standard on the motor. It kept stalling intermittently at idle. Usually at the worst possible times. This forum has been the saviour of my sanity many times.

Sounds like you have had a fair look over the motor. My advise would be to go back over and do a tune (link and sync) after you have cleaned the carb. Check you float level with the carby inverted and get the float level with the body of the carby. Check to see if the needle and seat seal well by trying to blow through the fuel intake line. It should seal well enough so you can’t get air through it.
Check the timing to see what the setting is. Make sure the timing advance is working correctly.

Whilst you have the carby off have a look at the fuel enrichment solenoid (electric choke) which sits underneath where the carby joint the motor. Try to blow through the black hose that came from the base of the carby. You should not be able to. Push the black button on top of the solenoid and this should open the valve and allow air through. When you release it should shut off again. If it is not sealing properly it will muck up the fuel mixture.

Another common problem with this motor is that the rubber grummet that holds the enrichment solenoid wares over time and allows the two electrical wires that power it to rub on the intake manifold and eventually ware the wires through. This wont cause your misfire but will make it hard to start when it is cold.

This is a photo of the solenoid to help show where the problem was.




You could also try running it on the hose at night and misting some water over the engine to see if there is a spark showing up any where which would indicate a short or cracked insulation.

Check all the recirculation and vacuum hoses for cracks or loose clamps.

I’ve done 140 hour with the motor now. Mostly ocean fishing. We do a lot of night fishing and are often the last boat in. The motor has been incredibly reliable once the bugs were sorted out.

Stick with it as you will find the problem eventually.

 

[1uz4x4]

Re: 1998 Force 75

Thanks for the encouragement, I cleaned the carb, looked good inside, not much to the little thing. I like the idea of running it in the dark. Maybe something will show up. If it doesn't clear up I'm pulling the flywheel to take a look. Still need to get get the DVA meter and study the recirculation system, still not sure how that works.
A boat mechanic I am not, to tell the truth I'm kinda having fun working on this project. I got a good deal on the boat so it doesn't hurt me to have to work on it.

 

[1uz4x4]

Re: 1998 Force 75

I'm redoing my recirculating system lines and just want to make sure they are the way they are supposed to be. My book does not show the layout that is on my motor.
I only have one carb.

I can run them back as I found them, not sure if it was correct or not. All check valves were OK.

 

[1uz4x4]

Re: 1998 Force 75

Never mind , just found it on **********

This picture is not in my seloc book.

 

[1uz4x4]

Re: 1998 Force 75

I checked my stator and trigger with a Dva meter.

Stator
Green with white tracer 276.5
White with green trace 284.6

Trigger
#1 Purple .558v
#2 White .751v
#3 Brown .845v

My book tells me a high reading on the trigger DVA indicates a bad ignition coil module.
I thought they checked out fine when i checked the diodes and resistance test.

Ialso noticed #3 plug is looking alot darker than #1 and #2. I borrowed an extra coil to swap around
to see if i had a bad ignition coil, i guess if i had two bad coils it was pointless.

Please tell me if I'm on the right track, I still feel like I'm lost.

 

[TwoFish]

Re: 1998 Force 75

I can't help you with the trigger readings but I'm following it with interest. I would like to test my coils and stator but don’t know how.

Attached a photo of the plugs from my motor. Top plug has always been lighter than the bottom plug. Local mechanic said it was normal. Single carb feeding 3 cylinders the top one always runs leaner than the bottom. Something to do with gravity.


#1 plug left, #3 right. The plugs had only done about 5 hours from new in this photo.




Did cleaning the recirculation system make any difference?

 

[1uz4x4]

Re: 1998 Force 75

The picture of those plugs look just like mine. Haven't had it on the water to really run it since I redone the recirculation lines. I can still tell it's missing just sitting in the yard on muffs.

Yellow wires that go to the regulator feel like they are getting warm, those are the ones I replaced the connectors on.

I was wondering if the readings from #2 & #3 trigger were high or is that a normal reading? specs say 0.5v+

 

[scottmm73]

Re: 1998 Force 75

specs say 0.5v+

If it says .5 volts+, I would assume anything higher that .5 volts is good. But you know what they say when you assume.

 

[1uz4x4]

Re: 1998 Force 75

Ran the boat the other day and checked the timing at WOT, 33deg advance at 4200 rpms. Talked to the local boat Guru here,Mr. Hudson, he told me to try champion plugs, back the timing up 3 deg.
He also wanted to make sure I was pitched right for my boat, might be loading up to cause the miss. I'm running a 12 x 10.5 now, can't go any lower.

 

[TwoFish]

Re: 1998 Force 75

If you prop has the 13 tooth spline like mine you can get the prop down to 8 inch pitch here on Iboats.

 

[jerryjerry05]

Re: 1998 Force 75

Is 4200 all the revs you can get??
Is the tach reading right,get a second tach or some way to check.

If your running 4300 I doubt your stator/trigger is bad.

Was the boat/motor a combo bought new or was it added later?
If it was added later then you'll need to get another prop.
People change motors and see a good prop and think it's ok to run like that.
It needs to be set up to run optimum.
I changed from a 17p to a 19p and my gas usage went up 20%

Miss: check the enricher(unhook) Carb setting(air screw) set at 1 turn out.
Then adjust from there.

 

[1uz4x4]

Re: 1998 Force 75

Ok, stopped and picked up 3 champion plugs,didn't help. So while running I unplug #3 coil to see if there was a difference, not much. Then #2, not any difference. Then#1, killed it. So I got my extra coil and put it on #1, then #2, then #3, all the same results as before.So now I believe I have a bad trigger. Two green wires with white tracer go to #2 & #3, white wire with green tracer goes to #1. Somebodey please tell me if I'm on the right track. Kinda excited to finally do some thing with some results!!!

 

[emoney]

Re: 1998 Force 75

Can you run 4200 rpms with a bad trigger? I have no idea, but this bumps your thread to the top so that Jerry or somebody sees it. Good luck.

 

[1uz4x4]

Re: 1998 Force 75

I feel real stupid, just realized those wires are from the stator. So I think I'll just buy both and hope thats it.

 

[jerryjerry05]

Re: 1998 Force 75

While your messing,try replacing all wire ends/connectors.
Thay can look good but inside the connection is bad.
If your running 4800/4300 I really doubt the trigger/stator is bad.
Put the right prop on it.Then test.
Check the reeds?Clean the carbs.Check the fuel pump diaphram.

 

[1uz4x4]

Re: 1998 Force 75

UPDATE. No progress. I've redone all connections on the ignition side of motor, replaced trigger. Still have the miss. Crazy thing now is I'm having trouble checking the timing with my light because I'm picking up signals from everything close to the motor. I can't even get close to the coils with the inductive clamp without picking up a signal and setting off the light. I checked all my grounds. Could be the rectifier? I'm going to go back over the tests for the regulator/rectifier.