Force 85 crawls at 10 knots WOT and has 95 psi compression

[SS Mud Bay Minnow]

My 1985 Force 85 3-cylinder Chrysler engine is on a Bayliner Capri 1600. It seems to start and run fine, but will only push the boat about 10-12 knots and never gets up on a plane. Other people say their Force 85 will drive there Capri 1600 in the range of 35-40 mph. This is with a load of about 500 lbs of people and equipment.

I tested the compression, and it is an even 95 psi in all 3 cylinders. I notice that Force engines seem to have compression of 120-140 in other posts here, 140 being new-from-the-factory.

The guy I got it from is a boat mechanic, and he had taken the boat in on trade for some work he was doing. He told me he cleaned the carbs (3 of them) and that was it, it ran.

I already replaced the fuel line and secured it properly at the engine and the external tank.It had been leaking at the fuel tank quick connect. I clamped down the hose on the engine too. I put in new plugs, Champion QL-82C's. It previously had some Autolites with a round electrode.

Supposedly the gas it was running on, in a tank from the owner, was premixed correctly, so I haven't

What are some diagnostic steps I can do to figure out why the engine is such a dog and then fix the issue?

 

[jerryjerry05]

The original plug was the one you got rid of. UL-18v Round electrode.
Does the motor rev up and just not go? Prop.
Or just not rev up?

The compression is probably OK just the gauge isn't reading right.
The important thing is all 3 cyl. read the same. Get another gauge.
The real readings should be with a good gauge about 150-155#
But again all 3 being the same is what your looking for.

First check the spark.
Then check the diaphragm in the fuel pump.
Make sure the linkage moves the trigger base when you accelerate.
Also the butterflies in the carbs all move at the same time and open to level or just about level.
I'm sure the others will add some more.

The first 3 post in this forum have tips and some tricks for the Force/Chryslers.Read them.

 

[SS Mud Bay Minnow]

Thank you!! I appreciate the gentle and constructive help.
I will read those threads.

Thank you for the plugs tip... I'll be darned if I could find one that clearly pointed me to that plug; the other charts and posts all seemed to point to the Champion QL82C. I'll go with your information, and just clean the original plugs (I still have them) and go with that.

I will check the spark at each cyl, though I'd expect it to be OK given that it sounds OK, but worth ruling out.
I'll look at the carbs opening too. I'll see if I can find the fuel pump procedure in my manual.

Yeah, it's a Harbor Freight compression tester, so maybe it reads out on a Chinese scale. Or maybe I'm just not screwing them in tight enough; seems I can only twist them by hand. In other threads people said these are about 140-145 PSI from the factory and more like 120 PSI is "normal" for an "experienced" engine.
I have seen advertisements for similar vintage Force 120's that show compression numbers ranging from 118-125 across the 4 cylinders.
Are there any threads that discuss the proper compression testing procedure, to make sure I'm doing this right?

 

[SkiDad]

my 1985 125 reads 148-152 on all cylinders - so I dont' think it's age - but that was with a good tester and taken from a warm engine - I run the NKG BUHX plugs on mine - in fact mine are 4 years old and I need to get a new set for next year. You can put some Mercury Quickleen in the gas and let it run though. Or you could get a can of sea foam spray and spray all the carbs for a minute at say 1500 rpm. Then shut it off and take the spark plugs out and put a liberal amount in each cylinder and then spin the flywheel and let it sit over night. I would change the sqeezie if you haven't.

wouldn't think you want larger than a 19 pitch on that boat but I would try a 17 pitch if you can find one - might be needed if the compression is a little low.

 

[Jiggz]

As Mitzysman mentioned, go with the NGK BUHX plugs for this type and model of motor, the NGK seems to be the better choice. Next, go to Walmart and buy a clear fuel filter (Fram G2) costs less than $5 and install it between the fuel pump outlet and the carb's inlet. Next go back to HF and find an inline spark tester costs also less than $6. Now for the diagnosis.

1. Use the inline spark tester and check for sparks on all cylinders.
2. Remove carbs' air cover, place control lever in full forward position and check the position of the throttles. All should be in horizontal position, no more - no less
3. Prepare motor for test run at the driveway on muffs, prime the fuel system and the primer should get firm in about 4~6 squeezes. If not there is probably a fuel leak in the system or the carb's floats are not set properly or the needle valve is stuck open. Check the carb's vent hole (a small hole on the side) for fuel leak. If it is leaking then the floats and needles need to be checked.
4. Start the motor and it should be idling around 800~1000
5. Try running the motor in fast idle while watching the clear fuel filter making sure it stays full. If not, then you have fuel delivery problem, i.e. faulty fuel pump, leaky fuel hoses, restricted pick tube or tank vent.
6. If everything seems OK, do a test ran on the water. Bring with you a spray bottle with fuel-oil mix in it. About 1/3~1/2 full is all you need.

If motor will not go above 10~12 knots at WOT, turn off engine, remove cowl and air covers. Check the condition of the clear fuel fitler. If it does not stay full or worse yet is is empty, you need to do step 5 again to investigate for cause. However, if it stays full, then you might have carburetion, electrical or reed problem. Do a test run again with another person driving, with clear traffic and a distance from shore. With the control lever at WOT and engine running but not going above 10~12 knots, spray fuel mix directly into each carb one at a time while watching for the engine reaction.

- If there is an increase in RPM, that specific cylinder is having fuel starvation problem
- If there is a decrease in RPM, that carb is working properly
- If there is no change in RPM, that cylinder is not firing at all, either it is missing a spark, broken reed, low compression or has improperly set throttle making the mixture too rich to start with.

 

[Scott Danforth]

SS Welcome aboard to iBoats

In addition to the motor troubleshooting, does the boat seam "Heavy"? this is a mid 80's Bayliner that is new to you, correct?

I recommend that you take the boat to a scale and have it weighed. According to the boat spec http://boatspecs.iboats.com/Bayliner__1600_Capri_BR__1985/bp/66b7225 your boat weighs in at under 1300# empty. add about 900# for a single axle trailer. If your boat and trailer is much heavier than 2200#, I suspect you may have a water logged boat.

 

[SS Mud Bay Minnow]

Thank you Jiggz!! I will try those steps!

I have a clear fuel filter coming any day now, ordered one via that South American Rainforest company; it's a filter that bikers use because it looks cool.
Before I replaced the fuel line and secured it at the motor, there was a pressure leak at the motor. New fuel line + hose clamp = no more. Now the primer bulb gets hard within a few squeezes. Before this fix, the primer bulb wouldn't get hard at all. I was hoping this was the fix, but no joy. It did make a difference in that the engine didn't cut out at WOT like it did before this fix.

The boat feels heavy when I'm trying to the the towing SUV to stop while driving in traffic. It pushes the SUV (97 Chevy Tahoe LS 4-door with 350) forward excessively when trying to stop in traffic. Maybe the SUV just has crappy brakes, but I swear a boat this size shouldn't push a big SUV like the Tahoe around so much. Where is a good place to get the boat and trailer weighed? Do I get weight of towing vehicle + trailer + boat first, and then weigh tow vehicle + trailer while boat is in the water, and subtract from the weight that includes the boat?

Mitzysman, some of the threads specifically said to avoid the NGK's with this motor and stick with the QL82C Champion plugs. The plugs that were in it were some Autolites. Some people said the Champions are the only ones this motor really runs right with. But those same people said QL82C plugs were the one, not the UL-18v. I'll search a little more.

 

[Scott Danforth]

The boat feels heavy when I'm trying to the the towing SUV to stop while driving in traffic. It pushes the SUV (97 Chevy Tahoe LS 4-door with 350) forward excessively when trying to stop in traffic. Maybe the SUV just has crappy brakes, but I swear a boat this size shouldn't push a big SUV like the Tahoe around so much. Where is a good place to get the boat and trailer weighed? Do I get weight of towing vehicle + trailer + boat first, and then weigh tow vehicle + trailer while boat is in the water, and subtract from the weight that includes the boat?

I think you answered your own questions. you should not even know the boat is behind the Tahoe, much less have it push you arround. do you have any soft spots in the floor? if so, you probably have an extra 1000 to 2000 # of water in the boat.

However to weigh your boat, find a local scale, drive on, disconnect trailer, weigh trailer and boat. your trailer is about 900# for a single axle. most truck stops, land scape companies, truck weigh stations, etc. will have a scale.

 

[jerryjerry05]

Still sounds like a performance problem and not really a weight issue.
My motors both 88/85's have 150# comp on all 6 cyl.
The comp test can be done cold or hot and you'll not see any difference.
I had a different 21ft Bayliner CC.Same as I have now .
It suffered from transom rot and held a lot of extra water. I figured probably 800-1000#
It really didn't make much difference. But I had twins and changed to a 225Merc.
Ended up chopping it up and taking it to the dump.(big job)
The foam had anywhere from 1 to 5 inches of water soaked into it.
The NGK or the Champion, even the Autolite's are acceptable.
I try to buy American made stuff(did you know Mexico and Canada are considered American, North American)
To test for extra water, park on level ground, lift the nose up as far as you safely can.
Remove the plug and put a bucket under the drain.
See how much water drains out.

 

[Jiggz]

No Title

Here's a specs sheet indicating the recommended spark plugs and other characteristics of the 85 and 125 HP. If you can post a pic of the spec sheet or reference about the use of the QL86C, it will be much appreciated.