1996 FORCE 75hp idle issue (especially when F to R)

[surfsalterpath]

re: 1996 FORCE 75hp cuts off when idling or going from F to R

These are the troubleshooting steps I've completed:
1: seafoam - yea, don't laugh!
1a: adjust all carb settings (never do this unless you know what you are doing!!!!) lol ~
2: new NGK spark plugs
3: new spark plug wires and voltage regulator
4: new water separator
5: new fuel filter
6: clean carb
7: replace all 3 REED BLOCK ASSEMBLIES (yes 2 of the 24 reeds were gapped open a little bit)
since I am a "newby" outboard mechanic I forgot to put LOCTITE on the 6 screws holding
REED BLOCK ASSEMBLIES on the reed adaptor plate! dumbass me!
8: sync ALL settings: throttle arm and cam linkage, WOT, timing, idle mixture, idle speed etc
THIS WORKED, at first! idling GREAT @ dock and after 2 short test runs. BEST EVER!
9: Long "test run" 1 hr @ 5000rpms and return to dock and FORCE dies trying to change gears!
BUMMED!

next on the troubleshooting agenda I have not done yet:

a: pull carb and intake manifold to add the LOCTITE to the 6 reed block assemblies I forgot to do the 1st time!
b: replace the primer bulb fuel line hose going to the fuel pump with BLACK "368 series" fuel hose. I have
grey fuel line (2015) from water separator to fuel pump. FORCE forums say grey fuel hose is a no no!
c: rebuild the fuel pump with new diaphragm kit
d: replace the rest of the fuel line (fuel pump2fuel filter2carb)
e: replace the recirculation one way valves and all recirc tubing
f: replace idle mixture screw and the inlet needle (tip wear??)


Ok, so what am I missing that I should consider to fix this "idle issue"

THANKS!

 

[Nordin]

Engine dying when shifting sounds like the mixture is to lean, the idle speed is to low or throttle/timing not properly synchronized.
How is then air/fuel mixture screw set?
1996 75Hp would be a 3 cylinder engine with one carb and the only settings is the mixture screw, idle speed screw and the throttle pick up point.
1. Mixture screw 1 1/4-1 1/2 turn out from seated
2. Idle speed 7-800 rpm in gear in water (about 1200 rpm at muff).
3. Throttle pick up point... the cam roller should touch the cam at mark at e cam.
BTW The 3 cylinder single carb 75Hp Force was not a good engineered OB.
Feeding a 3 cylinder engine with only one carb.........no not to easy.

 

[surfsalterpath]

a: I have the "crank timing" timing set at 32B like the manual says.
b: the idle mixture screw is set at about 1 to 1 1/4 turn out. That is what sounded the best. Seemed to smoke more & chug @ 1 1/2+ out.
c: prop on - in the water - idle speed screw adjusted to 950rpms. And I am trying to overcompensate for idle cutting off.
Anything lower sounds like engine is laboring to stay on.
d: yes, cam roller mark is in middle of elliptical roller and just barely touching it.

The weird thing was engine was idling/running GREAT @ dock and on 2 short test runs. The only other thing I can think it might be is that I FORGOT to put LOCTITE on the reed block assembly screws and they vibrated loose ????? in that hour 5000rpm run? ?? I was getting avg 22mph on a 24' pontoon on this 5000rpm test run when all I could muster in the past was about 18mph.
Or maybe the fuel pump diaphragm is acting up. The primer bulb is hit or miss on staying firm at all times. When we had engine dialed in at dock primer bulb stayed firm. After the long test ride now it's hit/miss. Gotta be a reason!
I'm going to get this antique outboard #purringlikeakittenAGAIN! lol ~

Agree on the 3cyl/1carb, but I must have got a diamond.
Been pretty decent since 1996. lol. All I need is 1 more season
it looks like, till the DF140bg arrives.
Who the heck knows when that will be!

THANKS for your advice! Much appreciated!

oh yea, the compression tested last year @ 135 across all 3 cylinders.
Is that ok for a 1996 FORCE 75hp?

 

[pnwboat]

Try replacing the fuel pump diaphragm, and the rest of the hoses. Not that expensive, easy to do, and a good thing to do if you don't know how old they are.
Primer bulb may get soft while running because you are sucking the fuel out of the fuel bowls into the engine. At idle or stopped, the fuel demands of the engine are reduced and the fuel bowls are not being drained as quickly, so the primer bulb is more likely to stay firm.

 

[surfsalterpath]

Try replacing the fuel pump diaphragm, and the rest of the hoses. Not that expensive, easy to do, and a good thing to do if you don't know how old they are.
Primer bulb may get soft while running because you are sucking the fuel out of the fuel bowls into the engine. At idle or stopped, the fuel demands of the engine are reduced and the fuel bowls are not being drained as quickly, so the primer bulb is more likely to stay firm.

Good advice! Thanks!
Ordered the "diaphragm rebuild kit"
Ordered the this series 368 3/8" fuel line:
"Shields Series 368 Low Permeation Marine Fuel Hose 3/8" x 10 FT"
Ordered this 3/8" primer bulb:
attwood Universal High-Output Primer Bulb, EPA and CARB Certified
(I do not like the crimped clamp fittings (prefer the SS worm gear clamps)
This bulb has good reviews, if that counts.

In the meantime I snipped the primer bulb fuel line (GREY - last replaced in 2015 attwood stock pre-made) ends (the tips were deteriorating) and removed the old crimped on clamps from primer bulb barbs and replaced w/ the SS worm screw clamps. This seemed to be a tight fit. Ready to get the GREY off and use the "series 368" fuel hose! And I ordered CLEAR 3/8" fuel hose to replace the black fuel line (not sure how old that is) from the fuel pump 2 the filter 2 the carb. It was suggested CLEAR to look for air bubbles in fuel line from fuel pump to carb.

Found excellent instructions on specs (tower shaft idle speed screw all the way out - measure from stud to actuator + 1/8") to re- install/fine tune the throttle cable, I was off about 7 barrel turns. Since that re-adjusted the "tower shaft" I re-synced the throttle arm/cam making sure butterfly was snapped closed when cam mark in middle+ of carb eccentric roller screw and butterfly perpendicular @ WOT. Re-set the "idle stop screw" and "idle mixture screw" - started at 1 turn out then used my ear in 1/8 turns to find the best setting. It'ss been said this US Marine/OMC/Chrysler FORCE 3 cylinder/1 carb design is not the best BUT it sure makes it EASY to learn and adjust settings. Good uncomplicated way to learn the 2-stroke basics!

YEA! This seemed to get me BACK DIALED IN!
About 2 hours on the water @ 5000+rpms and varied a lot.
Upon return to dock the FORCE held it's idle this time! WHEW!
And this AM started ok, idle was at 800rpms instaed of the 1100rpms where I set it yesterday. ODD! But it still held idle, though chugging. Also, after about an hour the WOT fell back to about 44-4600rpms. Kinda strange but still sound like it was running cleanly. Might have had something to do with my trim adjustments under way.

Also the engine is THROWING LOTS OF WATER up while WOT so I thinking this outboard was mounted TOO LOW? If I get the gumption I might go ahead and put the jack plate on I'm going to use for the DF140bg and toy around w/ the caviatation plate depth.

Still have the reed block screws to do (after return last noght I was seeing some oily gas in the carb throat - from the reed blocks loose???) and replace all the fuel lines and rebuild the fuel pump diaphragm. I sure hope this really gets this 1996 FORCE 75hp dialed in. I feel good about it now but I want to feel GREAT and listen to this antique #purrLikeAKitten!

The boat shop we bought the boat from in 1996 has closed. They did ALL the mechanic work. (old school shop) but KNEW their stuff $$$ ! lol ~ When I went shopping for the Suzuki DF140bg and was told he had NO IDEA when outboard would arrive, that put me in a quandry. I asked him could he fix my "idle issue' and he said he would rather not dig into this old engine. So, guess what? Here I am, bought the specific SERVICE MANUEL, about $1000 in parts and learning way more than I ever thought there was to a 2-stroke (should have done this 20 yrs ago - would have saved a LOT of $$$, less headaches and self-satisfaction ~ it's not rocket science) to save a boating season on the salt waters of Bogue Sound in coastal NC!

#WINNING ...... so far! lol~

Much appreciation for the tips! Helps a LOT!

 

[jerryjerry05]

The only time the bulb stays firm is when you pump it up before starting.
Once it's started, the ball just sets there and fuel flows through the one way valve. IF?? it's hard then? it just might be old and stiff??

 

[surfsalterpath]

The only time the bulb stays firm is when you pump it up before starting.
Once it's started, the ball just sets there and fuel flows through the one way valve. IF?? it's hard then? it just might be old and stiff??

........ good advice to know!
My Friend that's been helping me says his Yamaha primer bulb stays hard all the time. I'll pay atten to this after I replace the primer hose, fuel lines and diaphragm kit.

THANKS!