Motor or Prop problem; Viking, Force 120 hp (1995)

[alvez]

I while back i replace the prop becouse it started to slip when i gave full throttle. I remember the top at that time was 35 mph at 5000 rpm. Now i can't get my boat to plain. at wop throttle it barely goes over 10 mph and start to slip again between 3000 to 4000 rpm. It could be a prop again but im starting to wonder. does saltwater and current effect the boat that much ? anyway i have a 1996 Viking 19ft, Lbs 1900. If somebody has input it would be great to hear it.

 

[jerryjerry05]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

Compression/spark test?
The current shouldn't have anything to do with getting on plane.
Mark the prop and see if it's slipping???
Does it rev up all the way?

 

[alvez]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

Compression/spark test?
The current shouldn't have anything to do with getting on plane.
Mark the prop and see if it's slipping???
Does it rev up all the way?

I did a compression check. I got 150 psi on each cylinder and I changed the plugs. When I started and rapped on the throttle. I got around 5000 rpm. it ran rough. sounded like it was missing. I adjusted the card a little. backed it up about 1 1/2 turns from seat. I'm not sure how to check the spark/ignition? the manual is junk. so anyway with that I took it out to the lake. it ran the same. didn't even go over 3000 rpm at WOT. ....for awhile it did hit 4000 rpm but it felt more like a clutch slipping in a car. just revs' up.....any idea's?

 

[foodfisher]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

As mentioned, draw the line across the diameter of the prop hub, make the clutch slip then check the line. If it's a broken line you have a spun prop. If the line is still intact come back and we'll talk some more. The low RPMs are a different problem. When the prop slips the engine runs faster with no increase in speed. You've got to seperate one problem from another for us to get a handle on it.

 

[alvez]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

I took it to the local boat shop. They found that a few magnets were missing from my flywheel. does anywon know what specifically is the purpose of the maganets and how does it effect the perfomrance of the engine.

 

[TwoFish]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

It just happens that I have my flywheel off at the moment as it had a broken a tooth and I had it repaired.

The two photos attached. One is of the inside of the flywheel to show the 6 magnets. The other shows the Stator and the three CDMs (capacitor discharge modules which are a bit like a coil in a car) which produce the spark for the plugs.

The stator has coils of wire inside it and when the magnets inside the flywheel go past the coils it produces a current. It is just a generator. The stator has two sets of coils. One charges the battery and the other supplies power to the CDMs. If you loose a magnet the stator will not generate enough power for the CDMs and the motor will loose power through lack of spark to the sparkplugs.

At least that is how I understand it.

 

[emoney]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

Which is what would cause it to not go above 10mph, I'd think. Not so sure that would create a "slippiing effect", but definitely the loss of power. When you changed the prop, did you use the exsisting hub or did you get a new hub? I'm asking this, in the event there is more than one problem still. These used the "Flo-Torq" hub, which is basically a plastic hub designed to break before damage to the prop. If you slipped the new prop over the old hub, odds are you will still have slipping. The square, center plastic block can usually be the culprit and you can find that for $19.00ish. I know this because I just went through it.

 

[alvez]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

New Flywheel installed. I though it fixed the problem but it did not. It would not go over 2300 RPM i called the mechanic it looks the stator needs to be replaced now. I was informed that the stator has a low and high RPM function. He told me he was aware that the stator was damaged from broken magnets on the flywheel. but he checked the resistance and it was within tolerance. But anyway new news to me. I just wished he would of told me the stator was damaged to begin with i would of okayed a replacment.

 

[jerryjerry05]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

Usually if they find one thing bad it's the problem??
Finding that the magnets chewed up the stator???
I think it should have been brought to your attention.
But look on the brite side the shop gets to make more $$$ Oh wait that's not so good is it
I'd discuss the labor situation with the shop.
Maybe they will give you a break?
One things for sure,Id look into a different shop?

As a mechanic,I won't give it back till it's fixed.
If they are just diagnosing and someone else is doing the repairs??
Still not right?

Profile? Location?
You might be close to someone who can help?

 

[alvez]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

I updated the profile. Rowland Heights CA

 

[Jiggz]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

Actually, if you would had exercised patience you could have saved tons of $$$, learn along the way and become a good troubleshooter and finally become a good boater. And all you need is a keyboard, camera and a set of tools. Always use the power of digital pics and you'll find out how easy it is to do long distance troubleshooting. Anyways, when you pick the boat make sure you run it on the muffs and use a in-line spark tester (about $5) on all plugs (one at a time) to make sure you have sparks and not misfiring. Goodluck.

 

[emoney]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

Great points, Jiggz & Jerry. OP, were it me, and it's not of course so take this with a grain of salt, but before I let them find a 3rd problem, I'd start diagnosing this issue on my own. How did they repair your "missing magnet" issue, with the purchase of a new flywheel or? Jerry is right, double labor to remove that flywheel is not going to be "fair". but there's not a lot you can do about it at this point.

Too many shops want to just throw parts at a problem and not diagnose the root cause. It's not their money, and it's like they're more concerned with getting the thing out of their bay than truly repairing it. Some of that comes from customers putting pressure on them, I'm sure, but other causes are new and inexperienced technicians. Tons of help right here and if you "play your cards right", all the great advice comes free. Pretty easy to weigh which path is better in this case. Good luck and I hope this is the last issue.

 

[jerryjerry05]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

I'm doing this for FREE?????

The guys in Australia say they are saving their $$$ to buy me a ticket.(you can chip in too!)

No wonder I didn't recieve any royalties???

 

[emoney]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

"Check's in the mail, Jerry" now go out and wait by the mailbox......

 

[alvez]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

I appreciate everyone's input. ....unfortunately I’m back to square one could you believe it. So far I've had a New flywheel replaced (Damaged), a New Stator (supposedly it was damaged), they fixed some odd's and ends in around the throttle linkage that needed repairs.....but I took it out yesterday can you believe it, it still didn't get past 2300 rpm.. Disappointing. Before I picked it up on Saturday, I witnessed the mechanic run the boat on the dyno. At WOT the motor ran at 4500 RPM. That was great. But the next day when i took it to the ocean it wouldn’t get past 2300 RPM...could it be a bad prop?

 

[emoney]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

Was he running it on muffs, btw? Also, you never posted what size prop you have now? If you're able to get higher RPM's in neutral, than when in gear (on the water), you can usually narrow it down. The difference of 2k in RPM's, however, I wouldn't automatically assume it was the prop, unless you're really, really overpropped. Usually a drop in RPM while under load points to either an air problem or a fuel problem. For example, just this past weekend, I had a problem with a vent on my fuel tank and didn't realize it. It was a booger to "warm up" I thought, but I justified that by the fact the motor had sat, unattended, for 2 1/2 weeks. I eventually switched to another tank because I wanted to add fuel to that one and she purred like a kitten, but again, I wasn't paying attention and just assumed it warmed up. Long story short, when I ran the fuel out of the good running tank and switched to the one with the vent problem, motor started to drop RPMs and cut in and out. Finally, it dawned on me to check the vent screw and I knew immediately that was a problem. I loosened the cap to almost off the tank and she ran like a perfect little lady.

All of this to just give you an example of how a fuel restriction, caused in my case by a vent screw, will cause a problem in gear, because when it initially happened, I drop it into neutral and she was running fine. Let's hear what size prop you've switched to, and then start looking at things like the fuel pump diaphragm, what type fuel tank are you using (if it's a built-in tank, maybe look at the vent hose pickup screen), any kinks in the fuel line, etc. etc. If all that's good, then maybe it's an exhaust issue, although this would be the 2nd thing I checked.

 

[alvez]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

Mr. Emoney, what does running on muffs and BTW mean?. When he ran the dyno the outdrive was in a water tank attached to hoses. I don't know much about that machine other then what i described. My prop look like a 17 pitch, about 14" dia. the boat guys said the prop was fine. How do i start looking into this fuel problem. it sounds to me it could very well be the culpret.

 

[emoney]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

BTW=By The Way. Running on muffs means feeding water to the lower unit with a garden hose attachment. You just answered that by in your reply that he was in a water tank.

You can start the fuel check by looking at your hoses and make sure there's no kink in them anywhere. You didn't say if it's a built-in tank or portable, so clear that up 1st. Next thing after the hoses is to pop the fuel pump cover off, it's on the Starboard side of the powerhead (if my memory is serving me right at the moment) and will come off with a basic screwdriver. Once you get that off, there's a paper-like "diaphragm in there that can tear or crack. If it is, it will need replaced.

If you have a built-in tank, you need to locate the vent hose. Follow it all the way to the tank and there should be a fitting securing it. Loosen that and pull the hose out. Not sure of your set-up, but there should be a "pick-up" screen on the bottom of this hose and those can get clogged, not letting the motor draw needed fuel. If you are running on a built-in tank, the simplest way to know if your problem lies here is to get a portable and take it back on the water. If it runs fine, then you're narrowing it down quickly. If the problem is exactly the same, time to focus on that fuel pump.

 

[alvez]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

I took a portable fuel tank as you suggested..without luck it still ran the same. But on the bright side i could eliminate the tank worries for now. My second thought on all this was. I had compaired my prop, with....an identical force 120 motor my boat man had in his shop. Making a long story short, What would be the right prop? I want to maintain about 5K rpm. I will probably buy one just to eliminate another possible cause....and compair it to the prop thats on my boat?

 

[foodfisher]

Re: Motor or Prop problem; Viking, Force 120 hp (1995)

What kind of boat? Look in the ski locker. Are you packing a lot of weight? Put it on a scale.