89,85HP Force-Loss of Propulsion

[TWFisher]

I recently purchased a boat w/a 85 hp force. The first thing I did, before buying the boat, was have a mechanic check it out. I know little about boat motors. The mechanic said the engine checked out except slightly low compression in #2 cylinder, but he felt it would be OK and may come up. We have been running decarb treatments. About 13psi difference. 150, 136, 148. The mechanic changed water pump, rebuilt fuel pump, changed all fuel lines, inspected electrical/ignition system, cleaned, boiled carbs,etc. Thourough inspection/service. I did not have a prop so he gave me one he had laying around, he used it as a steering wheel puller and its about 37 years old.

I took the boat out for a test run. The engine starts like a champ and eruuns good except two things occoured that have me concerned.

1. Through the lower range of throttle, all is good, decent power, but when in the higher range, full throttle, I suddenly loose propulsion. It returns again in lower range of throttle. This problem is intermiten, some times I can run at full throttle with no issues. Im getting two replies to this: One, the prop is spun and needs to be replaced; Two that the prop is fine, if it had spun it would not return in the lower range of throttle. Not sure which way to go. What else could it be or is it likely the prop.

2. I seem to be missing a range of throttle. When pushing the control forward, the boat accelerates to a point, and as I continue to push the throttle forward, no change, then all the sudden the bow jumps up and it takes off. On one occasion, I pushed the throttle forward, with no change in accel, took my hand off the control, about 1.5~2 seconds later the engine responded, the bow came up and... My mechanic seems to think it has something to do with the S cam.

Any thoughts greatly appreciated.

 

[Barnacle_Bill]

Re: 89,85HP Force-Loss of Propulsion

Under the circumstances you need to get a good prop on her and then do your testing.

 

[roscoe]

Re: 89,85HP Force-Loss of Propulsion

yes. hard to diagnose multiple problems that overlap.

Bet a new prop will help - big time.

Then you will probably need to link and sync the carbs - check/set timing.

 

[TWFisher]

Re: 89,85HP Force-Loss of Propulsion

Ok, thanks,

Get back to you after a run w/new prop.

Thanks,

 

[jerryjerry05]

Re: 89,85HP Force-Loss of Propulsion

You said low compression.How low? Too low and you bought a boat with low compression your mechanic should have steered you away.
Come back with comp result before and now.
The prop should be replaced before it goes completley.
Good luck.J

 

[TWFisher]

Re: 89,85HP Force-Loss of Propulsion

The first test was i think 150, 136, 148. There was a 13psi difference between the hi and lo.

Ill have to get back with you on what it is now.

 

[TWFisher]

Re: 89,85HP Force-Loss of Propulsion

I've been relying on my mechanic to check compression tests, but Im going to buy some guages so I can do it.

How is it done? Just plug into spark plug hole and bump the engine? Can the guage set be bought at auto parts store?

 

[TexasBayFisher]

Re: 89,85HP Force-Loss of Propulsion

I've been relying on my mechanic to check compression tests, but Im going to buy some guages so I can do it.

How is it done? Just plug into spark plug hole and bump the engine? Can the guage set be bought at auto parts store?

You can do it yourself, yes.
You will need a compression tester
Goto Harbor Freight in Houston and pick up item # 95187
Which is this set here:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95187
When you go in the store look for the automotive aisle, that's where you'll find it and the whole set is only 20 bucks!

To do the compression test, remove 1 plug at a time and turn the engine over by jumping the solenoid with a remote starter button (also available from Harbor Freight for 7 bucks).
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=35448
Spin the engine over for a couple of seconds, that will give you a peak reading. The gauge stays at the maximum pressure reading until reset.
Remove tester, replace spark plug, do the next cylinder.]

PS. Your compression seems great. 140+ is excellent
Spray a constant stream of Quicksilver Power Tune into each carburetor while it is running at a slightly elevated idle until the can is empty then shut the engine down immediately. Let it sit for at least 6 hours, then take it out and run it hard.
Better yet, do a compression test and find out which cylinder is weakest, and spray a little extra in that one! You want the cylinder to bog down completely so that the power tune dissolves all the carbon causing the rings to stick. Sea foam "deep creep" (spray can) works for this kind of thing as well.

 

[TWFisher]

Re: 89,85HP Force-Loss of Propulsion

Sounds good , thanks!

One thing, this engine fires up very easy, will it start with the plug out? I dont want it firing up on me. Or, do I leave the key off to prevent this?

Thanks,

New to this....

 

[TexasBayFisher]

Re: 89,85HP Force-Loss of Propulsion

Leave the key off when you are jumping the solenoid. All you want to do is make the engine spin a few times so you can get a compression reading.

When you find the weak cylinder spray a bunch of power tune in it and leave the spark plug out. Turn the engine over by hand or bump the starter to coat the cylinder and let it sit for a couple of hours, then crank it over to extract any remaining fluid before replacing the plug. If you put the plug back in with a cylinder full of liquid it will hydraulic lock and damage the engine.

 

[TWFisher]

Re: 89,85HP Force-Loss of Propulsion

Ok, got it.

Yeah, I can see turning over the engine w/plug in and full of liquid really tearing something up!

Thanks again,

You been out any, heard anything about San Luis Pass, West Bay? I landed a nice 24lb bull red out there end of December.

 

[TWFisher]

Re: 89,85HP Force-Loss of Propulsion

Ok, first compression, after fresh from sitting up for years, 150, 135, 149.

Today, after decarb and running 24 gal of treated fuel, 135, 130,130. Sound OK? Decent range? Glad they leveled out, but wish they would have leveled out around 150.

Now I have another problem. Looked like the selinoid went out. I trouble shot and found the ground wire to the selinoid is not grounding. I jumpered to a ground on the block and selinoid worked, motor started and ran. When I went to shut down at the key and nothing, I can take the key out and the engine keeps on running. I had to choke to kill. I know Im getting ground to the block but it's lost some where in between. This thing is driving me crazy! I really need to get the manual............

 

[john from md]

Re: 89,85HP Force-Loss of Propulsion

When you say the solinoid stopped working and then you couldn't shut off the engine, I say that your ignition switch may be going bad. Both of those circuits are controlled from the ignition switch. The reason that the engine won't shut down is because the ignition switch is not grounding the white wires that go to the CDI units.

As to the other problems. The loss of power is probably two things. 1) the spun prop, and 2) the timing between the carbs and the trigger coil is off.
Fix these and it will probably run like a bat out of hell.

Setting the timing is relatively easy if you follow the instructions in the book and take it step by step.

John

 

[TWFisher]

Re: 89,85HP Force-Loss of Propulsion

Thanks John,

Can I test the ignition switch? If I have ground at the switch, safe to say that something inside the switch is not making contact, thus bad switch? But if no ground at the switch, then must be lost somewhere in between. Sound right?

Im hoping Ill have a prop the end of this week. I want to see if this helps me on the top end before I go into the timing issue.

Boy, after all the time and money I've invested in this thing, it sure is going to be nice to go fishing! I hope I dont miss the whole spring season! Before I had a boat I surf fished all the time, now that I have a boat, I dont fish at all, I work on the boat. Something is not right with this picture!

 

[john from md]

Re: 89,85HP Force-Loss of Propulsion

To test the switch, do the following.

Disconnect your battery.

Hook up an ohmeter negative lead is to ground.

Touch the white wire terminal with the switch off and you should get continuity. Turn the switch off and you should lose it. If this works, do the same thing to the white wire on the terminal board on the left side of the engine.

This will tell you where your problem is for the engine shutting off.


As far as working on the boat, it will get better as you are just making up for folks not keeping it up in the first place. Once you have it stabilized, all you have to do is routine upkeep and it will last for years.

I know, mine is an '85 85hp.

Regards,

John

 

[TWFisher]

Re: 89,85HP Force-Loss of Propulsion

Thanks again,

Let me get a good tester and Ill try it out.

 

[TWFisher]

Re: 89,85HP Force-Loss of Propulsion

I took the boat out for a test run. The engine starts like a champ and eruuns good except two things occoured that have me concerned.

1. Through the lower range of throttle, all is good, decent power, but when in the higher range, full throttle, I suddenly loose propulsion. It returns again in lower range of throttle. This problem is intermiten, some times I can run at full throttle with no issues. Im getting two replies to this: One, the prop is spun and needs to be replaced; Two that the prop is fine, if it had spun it would not return in the lower range of throttle. Not sure which way to go. What else could it be or is it likely the prop.

2. I seem to be missing a range of throttle. When pushing the control forward, the boat accelerates to a point, and as I continue to push the throttle forward, no change, then all the sudden the bow jumps up and it takes off. On one occasion, I pushed the throttle forward, with no change in accel, took my hand off the control, about 1.5~2 seconds later the engine responded, the bow came up and... My mechanic seems to think it has something to do with the S cam.

Any thoughts greatly appreciated.

Well, I havn't been out since the original post and havn't found a new prop, but I did get a manual and did some looking arond out in the driveway. I figured out the ignition switch problem I was having earlier and started the motor on ear muffs. As always it starts and idles pretty good. So I tried throttling up and the engine ran very erritacly. If I had a RPM guage I would see big swings. It sounds very rough. I belive this is the same problem I was refering to when I said it seemed like it was missing a range of throttle. Two things that are glaring out at me since I now have the manual:

See attached pics...

1. Notice the gap between the throttle cam and the roller. The manual says that I shold pivot the cam forward until it touches the roller. My cam will not touch the roller for some reason and Im not sure why. Probably 1/16" to1/8" gap. Ever seen this before? What problem would this cause me, if any?

2. Notice the terminal block. Lets say that from left to right is 1-12. I found the brown/blue wire in the lower left of the pic disconnected and tucked behind the coil mounting plate. The manual says it comes from module #3 and goes to 2. And then 5 and 6 have no wires attached. The manual says 5 should have a green/white wire from module #3 and 6 should have a red or red/white wire from module #3.

Any ideas what I have going on here? I havn't pulled the mounting bracket to do further investigating yet, it got late on me and I wanted to see what kind of feed back I could get from you all.

As always, any help is greatly appreciated.

TW

 

[TWFisher]

Re: 89,85HP Force-Loss of Propulsion

I forgot to mention, when I made the first test run, the throttle cam was moved forward guite a bit inorder to make contact with the roller. The mark on the cam was well below the roller.

 

[TWFisher]

Re: 89,85HP Force-Loss of Propulsion

My cam will not touch the roller for some reason and Im not sure why. Probably 1/16" to1/8" gap. TW

Let me rephrase this. According to the manual, I should line the mark on the cam up with the center of the roller and at this point the cam should be just touching the roller. As you can see I have a gap at this point. The cam will touch the roller but I have to place the mark well past, below, the roller. Although the roller is ecentric it's adjusted out as far as it wil go.

 

[roadrunnr]

Re: 89,85HP Force-Loss of Propulsion

The cam roller is on an eccentric and is adjustable. I believe it is one of the first adjustments in the carb link and sync proceedure, which should be detailed fairly well in your manual. Take Roscoe's advise and go through the entire proceedure step by step and see if that makes a difference in how the carb mechanics look to you. Your compression is great! Don't be concerned over the lower reading, two different gauges won't give you the same reading. The important things here are that the readings are well above 100PSI and within 10 percent of each other. You may be battling multiple problems, don't give and keep us posted!