1983 Bayliner with 85 HP force engine # 3 cylinder will not fire

[RJ Gilgenbach]

Have 125 compression on all 3 cylinders, good spark at plugs, # 3 cylinder not firing??

 

[kbh121956]

What do you mean? "good spark at plugs" Does number 3 plug have spark? Post your model number as it will also help.

 

[jerryjerry05]

Can't remember if #3 operates the fuel pump??
If it does it could have a bad diaphragm and feeding excess fuel into the cyl. and killing it.

Also if a gaskets gone bad it can do the same thing.

Spray starting fluid around the base of the intake.
If it makes a change? then there's a gasket gone bad?

 

[RJ Gilgenbach]

# 3 plug fires (assuming top plug is #1) as well as #1 and #2 plug....removed #3 while running...no change in motor..
I'm thinking a fuel problem with #3 carb....checked and cleaned the carb....swapped with #2 carb to see if problem changes..
will try the starting fluid test.....
Thanks for the responses and advice.....will update....

 

[RJ Gilgenbach]

Current update on my problem with 85hp Force.
Engine model is: 856x3l
Compression test:
#1 - 130 no bleed off
#2 - 130 no bleed off
#3 - 120 no bleed off
#3 spark plug is firing (tested out of port against metal shows good spark
Cleaned carbs, swapped #2 carb with #3 carb no change
Sprayed fuel into #3 carb port no change, did not fire
# 3 plug when removed has gas / oil present on plug, so I believe the cylinder is getting fuel to plug.
Question: is 120 psi on cylinder #3 too low ??? to fire the fuel mix?
any thoughts would be appreciated and what my next steps would be....Thanks guys

 

[jkoppen73]

#2 operates the fuel pump on my 85 h.p.

 

[RJ Gilgenbach]

Is anyone able to help me out on my question re: 85hp force engine not firing on #3 cyclinder???

 

[Jiggz]

Most likely, your problem is related to reeds. You already removed the #3 carb. Remove the intake adapter plate and inspect the reeds. A broken reed will prevent a cylinder from firing despite getting a little bit of fuel into it and indicating good compression.

Even if you spray fuel oil mix directly into the carb,a broken reed will still prevent combustion.

 

[jerryjerry05]

Any water drops on the #3 plug?
I had a 85 with 145# comp on all 3 cyl.
The #3 was missing under load.
The head gasket had a pin hole leak leaving water drops on the plug causing the problem.


When turning over does gas come out the front of the carb?
Remove the plenum/cover and check.
A small amount might come out normally??

How did you check for spark? This type tester, set at just about 1/2"
Another motor same problem, the trigger leads were broken under the shrink wrap
at the connector. It would fire when cold then as it warmed up the contact would break causing a miss
or no fire.
Try swapping the coils around and see if the problem changes holes?

They sell a bore scope for the newer style phones.About 20$
You can inspect the reeds without removing the intake manifold.​

 

[RJ Gilgenbach]

I checked the reeds and they looked very good....tension wise and no light coming through...swapped # 3 with # 1 no change in problem...Trying to remove flywheel...a real pane...I belive I have a wiring issue under the flywheel...had wires rubbing on shifter a couple of years ago...repaired worked fine...Now that I think of it...it seems to be the same symptons...
wont know until I get the flywheel off and really check the wiring...any good recommendations on pulling the flywheel
wont budge with my 3 prong puller....Thanks for all the input....

 

[jerryjerry05]

Heat will help remove the flywheel.
You use a big hammer once the 3 jaw was put under tension?
Usually a good whack will jar it loose.

A torch, apply heat on the threads, get hot but not red hot.
You'll probably melt the plastic in the nut/threads.
Get it hot and again a good whack should knock it loose.

 

[RJ Gilgenbach]

The saga continues:
Here is where I'm at with the force engine....
Plugs removed compression is at 140-142for each cylinder, no bleed off
carbs removed, checked reeds, look good, swapped #2 reed with # 3 reed, no change in #3 cylinder, not firing
swapped carb # 2 with # 3, no change in #3 cylinder, not firing
Swapped #3 coil with #2 problem did not move.
Have not changed the CDI module, as I am getting good spark to #3 plug, with inline spark checker, and with plug removed
getting good spark when grounded.
Still not firing on cylinder #3.....
Getting gas to plug....#3 wet when I remove it...all new plugs.
Question is what am I missing....is something shorting out plug when installed preventying the plug from firing?
I stripped out #3 plug last year, replaced with helicoil and ran fine....I did notice that #3 plug with new helicoil does not sit as deep as #1 & #2 plugs due to helicoil replacement, @ the size of the plug ring....since it ran fine last year I assume this should not be a problem....this is kicking my butt.
any ideas????? on what to do next?

 

[jerryjerry05]

Try swapping the packs.

 

[Redbarron%%]

Check for spark with an inductive timing light clamped over the wire.
I had some spark with my Sport Jet 90, but #3 cylinder would not produce power.
clamping the timing light over each plug wire showed that #3 was not firing all of the time.
My problem was a bad trigger coil for #3.
When I changed the trigger I also replaced the switch box and coils with CDM packs from a later Mercury and a three cylinder Mercury wiring harness.
Careful as I found that the color codes for the cylinders were different. I set them right using the timing light to figure out which wire went to which cylinder.
I don't know if they are compatible with your setup in the older Force, however.

 

[RJ Gilgenbach]

Thanks for the feedback guys...will try swapping the cdm packs and the timing light....will update..

 

[RJ Gilgenbach]

Latest update....
I checked the trigger (ohms and DVA volts measured correctly per my Cymer manual...
Checked the stator and results where within range...
Checked wiring for loose and broken on stator and trigger all appeared to be good.
Now I'm thinking that it's not an an ignition problem, so I pulled the head and rechecked the pistons #3 in particular and all
looked good no pits or cracks, cylinders are smooth no grooves.
I pulled the exhaust port and water leaked out. Now I'm thinking water is fowling out the #3 spark plug causing a no fire condition...#1 and # 2 cylinders are firing and I do have good spark to # 3 plug. Question is why is there water in the exhaust port ....Should there be?? not a large amount but when I pulled the exhaust cover a trickle of water came out.
Head gasket looks good, no cracks or pinholes...and as stated in previous posts compression was good with no bleed out. Any ideas on the water or am I barking up the wrong path???

 

[Redbarron%%]

You may have a leak in the exhaust manifold letting water get into the #3 cylinder.
Does the piston look cleaner than the others?
Also can you see a little drop of water on the plug or id you turn it over a mist coming out of the plug hole?
Did you check for spark with the timing light clamped over the #3 wire?
If you get a flash then you are getting a spark.
My sport jet had water getting into the exhaust manifold from an incorrect gasket and other stuff.
If the compression reads a good bit higher on #3 then water might be a good reason

 

[jerryjerry05]

If you have spark then the stator, trigger are probably ok.
Check the flywheel key and see if it's right?

When you removed the exhaust cover you should have some water come out.
It is after all a water jacket .
Try to see if the gaskets are leaking into the dry side.
The exhaust and water mix farther down in the exhaust.

 

[RJ Gilgenbach]

I checked # 3 cylinder with timing light showed good spark. I think what is happening is #3 cylinder is somehow flooding out with excess fuel and plug is shutting down and not firing the fuel mixture...I removed all 3 plugs and placed a piece of paper in front of each cylinder. #1 & # 2 cylinders are not spraying fuel out of plug holes....# 3 however is spraying fuel on the paper when I turn the engine over for @ 10 seconds...
Why would this be happening?? I shouldnt have any fuel being sprayed out of the cylinders...Right?

 

[jerryjerry05]

Spraying fuel?? you sure it's gas and not water? (had to ask)
Instead of paper use a mirror.

Post a closeup pic of the fuel pump and the hoses.
The bottom cyl. The fuel recirc system might be feeding excess fuel back into the bottom cyl.

Had a 50hp.Mercury with a similar problem.
He had excess fuel on #2 of 4.
Turns out the intake side had a crack in the block.
Might not be your problem, BUT??