1997 Force Outboard 120HP Idle & Trottle issue.

[Themanofsteel]

I recently purchased a 1998 Bayliner trophy with the a 120HP force. Sometimes it idles but for the most part it usually dies. When I start it, often I have to throttle quickly before it dies on me. Once Im able to throttle, it drives fine but when I go to idle it eventually dies and can be hard to restart.

Recently the issue seems to have worsened. I couldn’t even throttle quickly because it would die.

its definitely getting fuel. I have a clear filter on the fuel line and it’s filled to the top with fuel. Plus when I squeeze the fuel pump it’s tight.

I recently changed the spark plugs and decarbed the engine with Power Tune and Seafoam. I haven’t checked engine compression.

any ideas of possible problems?

 

[roscoe]

Getting fuel but not proper amount.

Clean the carbs, adjust them to factory spec, sync them probably, then adjust idle speed.

If fuel is old, replace it.
Then look at the inside of the fuel lines, as they deteriorate with age and exposure to the ethanol in the gas.

 

[jerryjerry05]

What rpm's at idle in the water?
rpm's at idle on the hose?
In gear in the water.800
Driveway on the hose, 1150-1200

You check for water in the fuel?
Is the powertune and seafoam still in the fuel?
You have a water/fuel separating filter? Get one.
Stop using seafoam(crap,my opinion).
It's about the same as adding soap to your fuel(again my opinion)

Do a spark and compression test.
Post your results.
I believe the later 120's will have lower comp on the top and bottom cyl.
Only about 10# "I think" not positive.

 

[blackd]

You might also consider cleaning the fuel recirculation system on this motor. If its like mine it has never been done (till I move it into the garage-mahal) later. Clogged recirculation can cause rich idle and symptoms similar to yours.

 

[blackd]

BTW, always run it dry of fuel after each use, and plan on cleaning the carbs at least annually. Cleaning the carbs, once experienced, is a relatively simple 1-2 hour job.

 

[Themanofsteel]

@Roscoe How do you sync?
@jerryjerry05 what a 'lower comp on the top and bottom cyl.'?
@blackd how do you clean the fuel recirculation?

 

[Themanofsteel]

Also, what is this connected to the top Carbuerator.

 

[blackd]

Go here to see the recirculation system:http://www.*****************/parts/me...0412TD/2009_70 or search (marineengineparts) if this site locks out the competitors link. Once there look up your model and serial # to get to the parts diagram and numbers.

That item is the primer solenoid (choke system). You can find that at the same site under Reed Plate & Primer section. It is usually activated by pushing down the key while starting. If that fails open it too will cause similar but more pronounced conditions.

Cleaning the recird system is to remove those small hoses and inspect for leaks or blocks. Remove the fittings and again check them for blocks or damage. There are small & fine screens that also need checking for blocks and cleaning. CAREFUL WITH THIS STEP AS THEY ARE SMALL AND FRAGILE AND HARD TO FIND TO REPLACE.

I hope jerryjerry05 will chime in and further describe.

 

[blackd]

Here's another try at the link (http://w-w-w.m-a-r-i-n-e-e-n-g-i-n-e...t-s/parts.html) The missing part covered by the ...is .(.par)

 

[blackd]

If you ar having problems finding the site the search argument should be marineengineparts

 

[Themanofsteel]

blackd Thanks

 

[Themanofsteel]

So I clean the carburetors really well. The floats were adjusted correctly. I replaced the inlet needles. I put it all back together. It seems to have fixed the idle issue except the it hiccups now and then.

Also now, it seem the when I throttle it sputters.

 

[Nordin]

Themanofsteel the "thing" connected at the top is a primer/enricher, instead of a choke.
It squeeze some fuel into the intake manifold.

Hiccups and sputtering sounds like too lean mixture.
How are the settings of the air/fuel mix screws?
Starting point is 1 1/8 turn out from lightly seated.

 

[Themanofsteel]

What is the setting for the mixture screw.

 

[jerryjerry05]

He told you.
Start at 1 1/8 to 1 1/2 out.

I believe in the first few posts in this forum is a link and sync for the carbs.

jerryjerry05

what a 'lower comp on the top and bottom cyl.'?
That's compression readings. The top and bottom might be 10# different than the #2-3 cyl.

The recirculation system on the 97 isn't like the older models.​

marineenginedotcom look up the 97 model recirculation system
The hoses(change) and nipples(blow clear) should be serviced yearly.

 

[Themanofsteel]

So the RPM are 1200. Approx. on the hose.
I changed the spark plugs a little less than a month ago and they look like the picture. Don't look good to me. This was the bottom plug but the others didn't look too much better.

 

[jerryjerry05]

The oil/fuel mix explodes and leaves carbon residue.
The black should wipe off.
No??
Then it might be getting too hot?

What kind of fuel?
What oil?

 

[Themanofsteel]

Unleaded 87, Masterpro Low-Smoke 2 stroke oil 50:1 mix.

 

[jerryjerry05]

Maybe do a de-carb.
Mercury's Power Tune or OMC's Engine Tuner.
Follow directions.
Then take it out and run it like you stole it.

 

[Themanofsteel]

So after removing and cleaning the carburetors, de-carbing w/Power Tune, and most importantly adding a fuel/water separating filter it runs good on the hose. Haven’t taken out on the water yet.

Did these boats come standard with a fuel/Water separating filter? This one did not have one anywhere, or the mount for it. Seems like something like that would come standard but maybe not.