Wrong plugs in motor

[Jkling]

I am a newbie to the boating world and have encountered a strange situation with my motor. I recently bought a 1986 Bayliner Capri with a force 125 outboard. I wanted to change plugs due to starting difficulty and found the plugs in the motor are not correct. Currently it is running with champion QL82C plugs. When researching force motors these are used in their 35 hp motor. With these plugs, the motor does run well once I have finished fighting it and get it started.

Hoping to make things better, I purchased the correct plugs for the 125. I went with the NGK BUHX. After getting them in it started a bit easier, however the motor stalls anytime I put it into gear. If I change back to the wrong plugs, no stall. I’m a bit baffled and was wondering if anyone had any thoughts. I’ve changed plugs in my vehicles many times, but again I’m new to boating so I figured I would ask some folks with experience. Thanks.

 

[The Force power]

Welcome to Iboats:welcome:

Your motor should run on those plugs!
Check if the engine is running on all cylinders by unplugging (while in idle) one cable at the time to check for RPM-drop.
(no drop in RPM, something wrong with that Cylinder/ignition)
Check the compression on each cylinder
Check /adjust the timing
Check fuel-pump/fuel-lines/tank-vent, Clean carburetors

There are useful sticky notes in this Force Forum at the top; read them all
keep us posted

 

[Jkling]

Thanks for the response. I’ll definitely read those notes.

I will unplug the cables tomorrow. I’ve never checked for compression before. Do I just plug the machine into each cylinder head and crank the motor? Will any fuel escape through the empty cylinder heads?

 

[roscoe]

Compression check should be done with a warm engine if possible.

Use a screw in compression gauge.

Flip the kill switch to keep the engine from firing, and to ground the ignition system to prevent damage.

All sparkplugs removed.
Throttle set to wide open.

Crank the motor over for 4 revolutions.

 

[Nordin]

Do as Roscoe says but maybe 4 revolutions is not enough.
Turn it over until the pressure stops to increase and the needle stops to move.

 

[roscoe]

Do as Roscoe says but maybe 4 revolutions is not enough.
Turn it over until the pressure stops to increase and the needle stops to move.

yep, my bad

 

[jerryjerry05]

You have a tach?
What rpm's in N in the water? Stalling going into gear, usually the rpm's aren't high
enough. should be about 800 in gear. 11-1200 in N

The difference in compression on a cold motor and a warm motor is almost none.
If you use the key to turn the motor over ground the plug wires even if the kill switch
has been removed. The factory techs said something about the packs can blow when
doing the test without grounding the leads???
If you can't get it started?? you'll do the test cold.
Unless there's something wrong with your fuel system, you won't be able to see any
fuel coming from the cylinders.

 

[Jkling]

My boat does not have a tachometer. I was thinking about getting a tiny tach but was not sure how reliable they are. A local boat tech. Told me the same thing about the idle speed not being correct. I think I am going to grab a remote starter button to totally bypass the ignition and not have to worry about grounding the wires. No kill switch on my boat.

ive never used a remote switch but after doing some research it does not seem too difficult to hook up so I’ll give it a try.

 

[jerryjerry05]

The Tiny Tach $35 when introduced was good for a couple of years then the battery died.
I bought a cheapo 22$ 5-6 years ago and it still works great.

 

[The Force power]

Some....tiny Tach. you can change the batteries on, just verify before purchase/ordering

 

[Jkling]

Ok... just got back from the marina. Motor started fine. While motor was running I pulled each plug wire. There was a noticeable drop in rpm when I removed cylinders 2,3, and 4. No change with cylinder 1. So, I was dreading checking compression but was glad when it tested well. Each cylinder was 130psi. I’m wondering if it could be the wire/coil. I noticed that the cylinder 1 plug wire gave me a bit of a zap. Seemed a bit more worn than the others, it also doesn’t seem to click down on the plug like the other three. Any further advice you guys could offer would be greatly appreciated.

Thanks for all the advice.

 

[The Force power]

Get a spark-gap tester ($10) to see if it can jump at least 3/8"
Inspect the spring inside the boot, they tend to rust (you can clean them with wrapping sandpaper around a drill bit and rotate in reverse direction)

 

[Jkling]

Thanks. I’ll give that a shot tomorrow. When I checked compression I used a remote start switch so there would be no spark. I’m assuming to check spark I need to crank from the ignition? Probably a stupid question but I want to be sure I am doing the right thing.

 

[jerryjerry05]

Yup need the key on.
Sometimes running the motor in the dark can show if the leads bleeding through?

I use Liquid Electric tape and coat the wire then a piece of shrink tube over that.
Change the end and as you do install the shrink tube and tape.

 

[The Force power]

I’m assuming to check spark I need to crank from the ignition?

You can "jump" the starter solenoid to crank the engine, so you dont need to use your key switch.
have you key set to ON & make sure your lanyard-switch is connected

Make sure you have a "tested good" battery when you crank the engine to check for spark.
It needs to crank 700 RPM in order to produce spark!
all ways ground the plugs if not in engine (you can blow the packs)

As Jerry mentioned already; check for leaks in the dark and/or wrap the cable, I've used dilectric-grease on the cables in the past and it works great

 

[Jkling]

I have not checked for spark yet but my son and I re-did the drop test. I wanted another set of ears to hear it. There does seem to be a very slight drop in rpm when the plug wire on cylinder 1 is pulled. It actually seems like the drop is more significant with each wire. The rpms drop more with #2 and when I pull #4 the motor actually stalls. I’m very confused because the motor turns over after the second turn of the key (choked on the first turn, no choke on second). If I had a cylinder not sparking would it turn over? When I take it on the lake it seems to run well, just a bit rough when going slow in the canal (5mph) and again with the proper plugs stalls when in gear. Could it simply be the idle set too low? I’m getting a tiny tach so I’m not guessing. I’m just not sure if the small rpm change on #1 cylinder when plug wire is pulled is normal. Sorry about the rambling, just getting a bit confused.