1994 Force 70hp need some input!!

[BDeHaven]

I was at the lake came upon a no wake zone so naturally I slowed way down on the other side i throttled up and the motor was a little slugish and only made it to 4000 rpms??? Normally my motor tachs out around 5100 rpms the motor also had a bit of a miss. I checked all 3 cyl. with my spark checker fire is jumping a good 1/4 inch. The motor also idles fine and out of the water today with water muffs on I punched the throttle and it quickly ramped to 5000 rpms ??? Im confused

 

[Frank Acampora]

Re: 1994 Force 70hp need some input!!

No confusion there. With no load on the prop, the engine only needs a couple of horsepower to overcome internal parasitic friction and rev-up. Even a poor running engine firing on only 1 or 2 cylinders or with a partially clogged fuel line will rev-up high on muffs.

"Gunning" it in the driveway proves nothing except that the engine will run.

Since you state that there is good spark on all three cylinders I would lean toward thinking there is some sort of fuel problem.---Bad pump, clogged oil recirculation, partial clog in the lines, etc.

You need to do more testing on the water and repost results.

 

[BDeHaven]

Re: 1994 Force 70hp need some input!!

I have preformed further testing. With a CDI/DVA attachment plugged into a fluke meter my readings are as followed. White & blk to brown 12 volts Ohms were 0, white to purple 11 volts Ohms were 0. Blue to ground 144 volts Ohms were 1002 Red to ground 89 volts Ohms were 120. I rebuilt the carb. and the fuel pump and rechecked all new fuel lines. I unplugged the attachment to preform the ohms readings.

 

[BDeHaven]

Re: 1994 Force 70 hp force... I went from needing input to needing a new motor???

Re: 1994 Force 70 hp force... I went from needing input to needing a new motor???

Checked compression today top cyl. 0, 2nd 80, 3rd cyl 100. What should I do now? Dont really want to invest alot of money in a motor that is no longer made. May just part it out??

 

[bentle]

Re: 1994 Force 70hp need some input!!

You prob.have done this already but just in case. Do a decarb first to remove possible sticky
rings and any other carbon build up in motor. Next do a compression test again and you will want to do this at wot with motor disabled from running. Wot meaning in gear fully forward throttle
and make sure you ground your plug wires to the block. Use a comp tester that you screw into
spark plug hole for best results. One other detail is make sure your battery is fully charged so you can crank at full rpms. Now what I find interesting is the low numbers you stated on comp you already did. I'm wondering how your motor ran at idle. Was it hard to start, did it spit and then die while on the water before your testing?

 

[Frank Acampora]

Re: 1994 Force 70hp need some input!!

I'm surprised you got 4,000 RPM running, with those compression numbers. You most likely need three overbores and three new pistons. If you do the work yourself, the overbore and pistons will cost around 550-600 bucks. Use that number to decide if you want to rebuild or not.

Personally, I consider a rebuild to be preferable to buying a different engine unless you are flush with cash and want to buy a new one.

 

[BDeHaven]

Re: 1994 Force 70hp need some input!!

Yes, It really had me confused as I stated early in the thread. The motor runs very smooth with a slight miss. I foucused most most of my trouble shooting on the elec. side of the motor. I will definatly try the decarb before tearing into the engine. From what I could see through the head there is not a whole in the piston or debri but the face of the piston is very black. What do you guys think about the reeds? Would you have to take the intake off to inspect them or removing the carb good enough? And when I say the top cyl. is 0 it is dead, not the slightest bit of pressure. Thanks for the input guys and I will inform everyone of new findings.

 

[Frank Acampora]

Re: 1994 Force 70hp need some input!!

Reeds will not affect compression. At this point, don't waste your time removing the carb and manifold to inspect them.

With zero compression on the top cylinder, there is definitely damage, not stuck rings. Don't bother with a decarb treatment. Pull the head and inspect the top piston, middle piston, and cylinders. Then decide if you want to repair the engine.

 

[BDeHaven]

Re: 1994 Force 70hp need some input!!

Tonight I pulled the head and found the porb. Im very surprised the cyl. walls were not torn up no deep grooves.View attachment 108703