1994 120 force o/b won't start

[brian66r1]

Re: 1994 120 force o/b won't start

What about the possibility of a failed head gasket?

Brian.

 

[stubtail]

Re: 1994 120 force o/b won't start

How is the timing and synchronization? From your pictures, I don't see a locknut at the top of the towershaft timing adjustment screw, but it could be on the other side of the plastic connector. Just thinking that if this had moved substantially, your timing may be out enough to create grief, even though your flywheel position is correct. I realize that this would be an extremely unlikely occurrence given the sudden nature of your failure to start, but at this stage of the game, me thinks you are open to any suggestions! You would likely require a timing light to check this.

 

[brian66r1]

Re: 1994 120 force o/b won't start

There is a lock nut on the timing adjustment. You are correct. It is on the back side of the tower shaft. Some time back I did try turning it in 2 screws and then backing it out 2 as well. Just to see if for some reason it made any difference but nothing. What gets me though. Even if it was a timing issue. And that's all I thought it could be earlier. There would be some attempt by the motor to fire/backfire/at least kick when I turn the key. It just turns over as though the plug leads were off the plugs. Got plenty of compression. Got good spark. Fuel going into carbs. Still fuel isn't getting drawn into 1 & 2 cylinders. The top 2 plugs and the number 4 plug just don't get wet.

I think I'm gonna have to pull the head off. At least to check the head gasket and make sure that there is no visible damage to the cylinders.

Brian.

 

[brian66r1]

Re: 1994 120 force o/b won't start

I think I'm going to have to spend some money.

Brian.

 

[pnwboat]

Re: 1994 120 force o/b won't start

Taking the head off and inspecting the cylinders won't hurt anything, however, with the compression at 140 (I assume this is 140LBS), I doubt that you will find anything wrong. I could be wrong but you never know LOL!

Correct me if I'm wrong, but you mentioned that even when you squirted some starting fluid or fuel directly into the cylinders, it still didn't fire. Even if the timing was off, reed valves broken, rings shot, wrong plugs etc it should at the very least, backfire or do something. Even though the spark "looks" good, it may not be enough to fire the plug under compression.

Did you ever check the stator windings? Also check to see that all six magnets under the flywheel are in place. This is just my opinion, and I am by no means an expert, but you might consider doing a few checks on the ignition system before you take the head off (and spend some money). Doesn't take but a few minutes and is very easy to do.

 

[brian66r1]

Re: 1994 120 force o/b won't start

I know. There's not even a hint of it kicking. I'll test the resistance on the coils and try take a video of me cranking it over and of the spark with a spare plug in the end of the lead and all the plugs in. Just to show how much spark there is with the engine under load. (all the plugs still in).

 

[brian66r1]

Re: 1994 120 force o/b won't start

Hmmmm. Between the red and the red/white stripe wires coming off the stator. There is 68 ohms.

Between the green and the green/white stripe wires there is 1.5K.

If the stator energises the ignition and the windings in the stator are partly shorted or crook. How come I still get such a strong spark?

 

[brian66r1]

Re: 1994 120 force o/b won't start

The measurement on the green - green/white stripe:

And the measurements on the red - red/white stripe:

Is this why I'm having such a problem?

Brian.

 

[brian66r1]

Re: 1994 120 force o/b won't start

Just tried cranking whilst I took some video with the phone. The second time I tried, I pushed the key in and choked it for a couple of seconds but it doesn't make any difference:

[video]http://s174.photobucket.com/albums/w117/mYZF_750/The%20Boat/?action=view&current=1d9b89b8.mp4[/video]

Then with all the plugs still in the motor, I took off each lead (1 through 4) and connected them in turn to the top plug in my dodgy little test rig. (nowhere near as good as your one PNW).

Number 1:

[video]http://s174.photobucket.com/albums/w117/mYZF_750/The%20Boat/?action=view&current=1691f71d.mp4[/video]

Number 2:

[video]http://s174.photobucket.com/albums/w117/mYZF_750/The%20Boat/?action=view&current=73266643.mp4[/video]

Number 3:

[video]http://s174.photobucket.com/albums/w117/mYZF_750/The%20Boat/?action=view&current=925924fa.mp4[/video]

And Number 4:

[video]http://s174.photobucket.com/albums/w117/mYZF_750/The%20Boat/?action=view&current=f6174fde.mp4[/video]

This test rig has got the BUHW plugs in it, not the BUZHW plugs that should be in the motor. Looking at this. The plugs are firing although not as strong as with the correct ones in. They look like they are firing a bit intermittently, a little bit hit and miss? Is this something to do with those out of range resistance readings across the coils on the stator?

Do I need a new stator?

Brian

 

[brian66r1]

Re: 1994 120 force o/b won't start

get back to basics we tried to run it on water.It doesnt compress.we have tried everything else.we have enough spark to make some sort of bang.Pull the head off and we will see whats going on.

 

[brian66r1]

Re: 1994 120 force o/b won't start

lol sorry brian posting in your name

 

[pnwboat]

Re: 1994 120 force o/b won't start

Those stator resistance readings are definitely not within specs. Green - Green/White (I think the color is actually Blue to Blue/White, probably faded a bit) should be between 3250 - 3650 ohms. Red to Red/White should be between 75 - 90 ohms. I agree with your observation that the spark seems intermittent at times.

I would say that your stator is bad. The stator generates the voltage to the switchbox which in turn fires the coils in the proper sequence. If the stator output voltage is low, the output voltage of the coils will also be low.

A little bit more information. The Blue and Blue/White wires are for the low speed stator windings. This comes in to play when starting the motor. The Red and Red/White wires are for the high speed windings in the stator. Your resistance readings for the Blue and Blue/White wires are less than half of what they should be. Pretty far off. The readings for the Red and Red/White wires are much closer to normal. I suspect that this is why on one occasion you did get it to start when it was at wide open throttle. The low speed winding in your stator is bad. Attached is some installation instructions for a replacement stator for your motor that explains the resistance readings etc.

View attachment 174-9710K1.pdf