Force 85 dies at idle, hard start

[IndyPaul]

1989 Force 85. Ran pretty well all summer until a couple of weeks ago. I think my son had used some small engine 2 stroke oil instead of marine grade for a couple of tanks. Starter was going bad as well. So i now have a new starter, new plugs, new fuel line and have fresh gas and marine oil. I also did a high concentration seafoam treatment (lots of smoke) It will now start but requires almost full throttle to do so. When i drop to neutral it dies. If it does manage to run it dies when putting in gear. I did a spark test and all plugs seem to be sparking. Any ideas?

I have looked at the carb timing tips but I'm hoping it is something easier and not sure if that would address this issue. I did manage to get it in gear yesterday and ran for a while at high speed and the engine ran fine until i got back to dock and it died when slowing down.

Video shows it idling and dying.
https://youtu.be/XLQzKwsAAAk

 

[Nordin]

Sounds from the youtube clip it is running on 2 cylinders, but I might be wrong hard to figur out when looking at videos .
When you run at higher RPM does it perform as it should?
First do a compression test, value should be 140-150 PSI, can be lower but it is important that it is equal and no more then 10% in different.
Check for spark with a timing light when idling.
If all this looks good then try to increase the idle and also check the setting of the air/fuel mixture screws at the carbs.
Initial setting 1-1,5 turn out from lightly seated.
To lean setting of the screws can cause this issue with the engine to die when going into gear.

 

[jerryjerry05]

Go for a ride, run it as fast as it will go for 5 min.
Then shut it off at the key.
Don't throttle back, just kill the motor, pull the plugs
and check the burn. Post results.
No more Seafoam, like adding soap to the gas.

 

[The Force power]

In addition...in my opinion...it looks like the idle rpm's are too low looking at the throttle-cam's position
Is this in "high idle" / "warm-up" mode? how does run in that mode?

Sorry, I did not mean to bud in (for my own learning purpose only)
You got the best two guys on it

 

[IndyPaul]

Thanks for the suggestions. I did a compression test and got about 125 on the first 2 and only 60 psi on the 3rd. So that's not good. I did bump up the idle some, but not too scientific. I don't have a tach.

Here is a pic of the plugs, they are new so can't tell anything yet.

Any obvious things to address the low compression on cylinder 3?

 

[Nordin]

125 PSI at #1 and #2 but only 60 PSI at #3.
Then you have to pull the head and inspect.
Perhaps a bad head gasket BUT check the cylinder walls and the piston at #3.
Maybe only a change of the piston and rings or you have to do a rebuild.

 

[jerryjerry05]

Pull the head or the bottom port cover.
Both can show if there's damage to the piston
or cyl. walls.
I bought a snake cam $11 for my Android
Works great.

 

[IndyPaul]

Thanks everyone again. This is likely becoming beyond my amateur skills. I may be able to replace the head gasket but any piston work sounds like something I'd have to hire done. I'm wondering if the cost to rebuild or do piston repairs would be worth it on a 31 year old motor? What kind of shop would do that? Most don't want to work on something this old.

 

[IndyPaul]

I know I need to get that head checked out, but as i was looking at the engine just now i see a hose laying disconnected below the carbs. I d9nt see an obvious place it goes. The first 2 pictures show the hose with a yellowish connector. The 3rd picture is where it is coming from. Any idea where that goes and what problem it would cause by not being connected?

Also, i feel dumb but I'm not sure where the idle air mix screws are. I don't see anything that looks like what I thought it would.

 

[The Force power]

I know I need to get that head checked out, but as i was looking at the engine just now i see a hose laying disconnected below the carbs. I d9nt see an obvious place it goes. The first 2 pictures show the hose with a yellowish connector. The 3rd picture is where it is coming from. Any idea where that goes and what problem it would cause by not being connected?

Also, i feel dumb but I'm not sure where the idle air mix screws are. I don't see anything that looks like what I thought it would.

I'm 99% sure the loose end with the brass fitting was at one point screwed into the air intake cover (black housing in front of the 3 carburetors)

Remove the (6) bolts (2 per carb.) to remove the metal air-box & re-attach hose/fitting
The function for that was when the motor is tilted up and fuel would leak out into the air-box collect and slowly get sucked into intake.

I also noticed,;the fuel line to the bottom carburetor is not properly attached and in poor condition
I would start with replacing ALL fuel lines if they have been changed with the new fuel rated fuel lines!!

The are few variations of carburetors used on these engines, So the air/fuel mixture screw(s) (one per carburetor) can be at the top in the throat of the carburetor OR on the side near the top will be a screw like bolt with a spring around it.

In either scenario of location the set up is the same!!
Turn them clockwise all the way in GENTLY!! Till LIGHTLY seated, now back them out 1 1/2 turn out (make sure you all three carburetors the same settings)

Here's a section of the late Frank S. post

8. NOW we adjust the mixture on the carbs. Set all low speed needles to about 1 1/4 turns out from lightly seated. Do not force as this will damage either the needles or the seats.
8A. With the engine idling in neutral, turn each the needles in equally about 1/8 turn at a time. Give the engine a couple of seconds between each adjustment to stabilize. Adjust until the engine either "sags" or stalls. Note this setting.
8B. Now go the opposite direction. Adjust until the engine runs rough, burbles, or stalls. Note this setting.
8C. Set all needles to the average between the two settings: That is, for example, if it stalled at 3/4 turn out and burbled at 1 1/4 out then set all needles to 1 turn out.
8D. Readjust idle speed to 700-750 RPM.
9. Take the boat out on the water and do a "hole shot"--Full throttle acceleration from a stop. If the engine "sags" then recovers and picks-up it is too lean. Open the needles about 1/16 turn at a time until the engine accelerates with no hesitation.
If the engine sputters or coughs or burbles, then clears itself and accelerates, it is too rich. Close the needles about 1/16 turn at a time until the engine accelerates smoothly.


10. I can NOT stress this enough! NEVER set the low speed needles less that 1 turns out no matter how poor the idle or acceleration. To do so will run the engine too lean and detonation and melted pistons at or near full throttle operation will result.

 

[The Force power]

Thanks everyone again. This is likely becoming beyond my amateur skills. I may be able to replace the head gasket but any piston work sounds like something I'd have to hire done. I'm wondering if the cost to rebuild or do piston repairs would be worth it on a 31 year old motor? What kind of shop would do that? Most don't want to work on something this old.

AS Nordin said:
Start with pulling the Head & inspect the head-gasket; you may just be lucky!!

You asked if its worth to repair a 31 year old motor, my question to you is; How much is a 1 year old 85 hp worth?
I'm up in Canada so our motors don't run a full year as they would in warmer climates and ultimately last long here.
Also (in general) stuff is cheaper in the USA then in Canada (except health care)

 

[Nordin]

The disconnected hose is as The Force power says.
It should be connected to the bottom of the air intake box.
The purpose of it is to collect and return fuel to the crank case that drips from the carbs when tilting the engine.
Yes the hose to the bottom carb is not fully attached to the fitting.

But your main issue is the low compression at #3 cylinder, the small issues above does not cause your hard starting and stalling when going into gear.
There is not any "quick fix" when you have low compression.
You have to pull the head and/or the intake cover at #3 cylinder and look.
Pics will show how much damage it is and if you have to change piston or do a rebuilt.

 

[jerryjerry05]

You'll need a 10-12" thin screwdriver.
The carb cover(plenum) has 3 rubber plugs on the front,
that when removed allow access to the air screws.
The bottom one you have to lift the cowl seal to access
the screw hole.
In 1988/89 there was a service bulletin that said the air screws
need to be set at 1 turn out and left there.
BUT!! not all 85/90's run good at that setting.
I had one that wouldn't run unless the screw was set at 3
turns out??

The 60# of comp will cause hard starting and make it run bad.
Pull the head and see why the comps low?

I bought a snake camera for my Android phone.$11

If you do get it started and continue to run it, you can hurt the
motor beyond repair??

 

[The Force power]

The carb cover(plenum) has 3 rubber plugs on the front,
that when removed allow access to the air screws.

I have yet to find one that still has the rubber plugs in place
lol

 

[jerryjerry05]

I guess you haven't been around long enough!
When I bought my boat in 88 the plugs lasted about
3 weeks.

 

[The Force power]

That's what I mean, these plugs all disappear:tea: or am I missing something?
Oh yeah..... the plugs:bump2: