85hp force idle air mix adjusment inop

[crracer]

Hi every one i have this problem with outbord motor its been acting up this last season the motor is a 1989 force 85hp. Tish is what going on with the darn thing at idle it runs rough like its missing and when trying to start it for the fist time it back fiers out the exaust but once its runging if i turn it off it starts right back upwith no back fire but still has the rough idel when i put it in gear the motor will some times die when under way the motor has a roughnees to it and seems boggy but a littel past quarter throtle it smooths out and runs awsome plenty of power from mid to the top end just at adel or in gear blow quarter throtle it runs rough. so when i try to adjust the idle air mix carb number 1 when i adjust the needles no chang in the way it runs i can seat the needle and no chang i have gone as far out a 4 full turns no change same thing with the number 2 carb but on the 3rd carb i adjust the needle there is a change in the way it runs for that cyl i screw it in and the idal gos up and a littel then it will die i screw it out then it runs rougher and a little mor turn then it will kill the motorand it runs best on the needle just under 3/4 of a turn out from fully seated. i dont know what esle to try here are thing ive done to try to fix the problem
compreson test cly 1. 140psi cyl 2. 145psi and cyl 3 . 148psi
cleand the carbs really well and inspected and cleaned all jets needles checked the float leavel ect.
new spark plugs ngk buhx
did a decarb with power tune
fuel pump kit
and even ran the motor on a remote full tank
none of these items have corrected the isue any help would be greatly help full

 

[SkiDad]

Re: 85hp force idle air mix adjusment inop

have you checked your spark on all 3 cylinders ? - you can get basic tester at a local auto parts store for about 10-15 bucks. Do all of your plugs look about the same burn wise and have same wetness if you pull them out and inspect ? I'm sure Jerry or Frank will have better advice when they see your post.

 

[pnwboat]

Re: 85hp force idle air mix adjusment inop

Maybe try a link and sync. Look under the "Sticky" at the top of the Forum listing for Force & Chrysler FAQ and other great info. . There is a subject titled Synchronizing Carbs and timing on a 75-150 Chrysler or early Force.

 

[Jiggz]

Re: 85hp force idle air mix adjusment inop

The fact that the top two cylinders are not affected with the fuel air mix adjustment and yet the motor runs great above half throttle, the idle ckt of both carbs are probably inoperational and this could be due to clogged idle jets. One test to verify this is by spraying fuel-oil mix directly into each carb while listening for changes in the engine rpm or run. If the engine sounds a little better when sprayed with fuel oil mix into each of the top two cylinders, it is definitely an idle jet or idle ckt problem on each carb.

If there is no change, then it could be a spark problem caused either by the trigger (which is moved when the throttle moves) or it could be power from the stator since both top cylinders are powered from the same CDM.

 

[jerryjerry05]

Re: 85hp force idle air mix adjusment inop

Clean the carbs.
The air screws are for low speed operation.
Above a certain rpm's the main jet takes over.

Remove the air screws and check for damage.
Any grooves or nicks and they need replacing.

The back fire could be too much fuel being draw into the cylinder,again cleaning the carbs should help.

Get a can of starting fluid.
Start the motor and spray the fluid around the carbs.
If it makes and change in the running,your sucking air somewhere.

 

[MickLovin]

Re: 85hp force idle air mix adjusment inop

Also check your fuel diaphragm, I had a similiar problem, cleaned out carbs, still didn't fix it. I pulled the pump off as I noticed air bubbles in my clear fuel lines. The diaphragm was cracked and letting to much fuel into the crank causing a flooding condition and not idling properly

 

[crracer]

Re: 85hp force idle air mix adjusment inop

Thanks everyone for all the advice I haven't had a chance to try much got hit with 8 inches of snow but I was looking under the fly wheel havnt pulled it yet but I did notice that the trigger has a littel up and down movement is that normal I will keep you guys posted on what ive found to fix the problem

 

[Frank Acampora]

Re: 85hp force idle air mix adjusment inop

Don't go pulling the flywheel. There is nothing under there that would cause the problem. And yes, there should be a little clearance in the trigger to allow free movement. The stator keeps it from rising into the flywheel.

 

[crracer]

Re: 85hp force idle air mix adjusment inop

Thanks frank I wont wast time pulling the fly wheel im allso going to replace my fuel line from the pump to the carbs and the one that run from carb to carb they are hard as a rock

 

[Jiggz]

Re: 85hp force idle air mix adjusment inop

Just to make sure we are all talking on the same page, can you post pics of the carb and maybe from there we can refer you how to check and clean the idle ckt of each carb. Make sure the pics show 3/4 view of each left and right side of the carb.

 

[crracer]

Re: 85hp force idle air mix adjusment inop

here are the pics of the carb it is the midel one i can take more pictures if needed let me know

 

[Jiggz]

Re: 85hp force idle air mix adjusment inop

Great. First thing to do is to remove the needle screw (idle mixture screw) all the way out. Inspect make sure the point is not damaged, blunted, bent or rounded. Second, use reduce air pressure of about 10~15 PSI with a blow gun, blow into the idle mixture screw port and you should feel air blowing into three ports, i.e. behind the throttle plate, idle jet base (bowl area) and in the idle air bleed port (optional if it exists, I can't see it from your pics though). See attached drawing referencing the low speed ckt. Any clog is indicated by lack of air blowing from any of the three ports. There are ways to unclog ports, i.e. blowing back or using fine wire. If all ports are clear including the low speed jet, replace mixture screw until slightly seated and then turn back one full turn up to 1 1/8 turn out. If problem continues after this verify the float level to make sure it is not set too low.

To see a bigger picture, double click the attached file.

 

[crracer]

Re: 85hp force idle air mix adjusment inop

thanks for the time to post that diagram helps me to under stand how the air and fuel flow in the carb. ill get back out to the garoge in a day or to and go through the carbs again thanks again jiggz

 

[oldboat1]

Re: 85hp force idle air mix adjusment inop

only thing I would add is a strong recommendation that you remove the expansion plug on the top of the carb (the red disc in the pic), under which the low speed needle seats. The drawback here is that you will need a replacement plug, as you will likely ruin the existing one getting it out. I drill a small hole in the top (just through the plug -- carefully to avoid hitting the carb body underneath). The plug is pulled up and out with a small screw driver, drywall screw, punch or whatever else you might have to pry it out. Clean the passages underneath with some carb cleaner and small wire, and clean the area where the needle seats from the front of the carb and from the area under the plug. Use a flashlight or hold up to the light to look into the passage for debris (like old packing). When finished, screw the needle lightly into place. This will give you a sense of what seating it feels like, and you will be able to see the tip of the needle in the area under the plug. Remove the needle. Replace the expansion plug, giving it a tap with a small hammer or similar to seat. Put a couple of packing washers on the needle shaft, and screw it in until it seats. Insert the valve nut over the needle, and screw it in. Tighten it to the point that the low speed needle can be rotated but will not rattle out of position. When the carb is reassembled the needle will be in the closed position, and will need to be backed out counterclockwise 1 1/2 turns to the initial setting. The needle should be bright and clean, with an undamaged point.

BTW: Agree that's an interesting diagram from Jiggz -- hadn't looked at it closely yesterday. It is a nice representation of how the mixture screw works in the carb.

 

[oldboat1]

Re: 85hp force idle air mix adjusment inop

Clean the carbs.
The air screws are for low speed operation.
Above a certain rpm's the main jet takes over.

Remove the air screws and check for damage.
Any grooves or nicks and they need replacing.

The back fire could be too much fuel being draw into the cylinder,again cleaning the carbs should help.

Get a can of starting fluid.
Start the motor and spray the fluid around the carbs.
If it makes and change in the running,your sucking air somewhere.

Hey Jerryjerry -- haven't tried that trick with starting fluid (still have my eyebrows ). It sounds like an old fashioned trick that would be useful. What's to say, though, that the carb isn't sucking in the vapors through the throat? Do you shield the front of the carb, maybe?

 

[Jiggz]

Re: 85hp force idle air mix adjusment inop

Note, if the carb is sucking air from somewhere other than through its frontal part, the problem will be present both in idle and high speed. If that is the case, this can easily be diagnosed using smoke from a cigarette or incense stick.

 

[oldboat1]

Re: 85hp force idle air mix adjusment inop

Ah. A throwback to the '70s when we had both incense sticks and cigarettes!

Jiggz -- I think you're darned close to a promotion. Mine just came through a few posts ago! Haven't seen the payraise yet, maybe because I seem to have been in grade for about 10 years..

 

[Jiggz]

Re: 85hp force idle air mix adjusment inop

Yup, younger generation will surely cringe to the idea of using second hand smoke to troubleshoot vacuum leaks and yet will gladly smoke weeds without exhaling! Lol. Last time I used this trick is when troubleshooting for vacuum leaks on a water distilling plant onboard a Navy ship. And yes, it works!

 

[crracer]

Re: 85hp force idle air mix adjusment inop

Hi fellow boaters. I would to tell everyone a big thanks for the help and advice you gave me my boat motor is running great starts right up and runs smooth and is very responsive and snappy no more long crank. No more back fire and it dose not die when I put it in gear from idle very pleased and my boating experience will be great this summer. One question is on my air fuel adjustments is that the motor runs great at half a turn out from lightly seated on all three carbs dose that sound like a ok place to leave the air fuel mixture? I am worried about burning it up. But it runs smoothly and responsive there so I think its ok. Things I did to the motor are rebuilt fuel pump. All new fuel lines rebuilt and cleaned carbs and set the float hight and new carb gaskets big thanks again im a happy camper now

 

[crracer]

Re: 85hp force idle air mix adjusment inop

Hi fellow boaters. I would to tell everyone a big thanks for the help and advice you gave me my boat motor is running great starts right up and runs smooth and is very responsive and snappy no more long crank. No more back fire and it dose not die when I put it in gear from idle very pleased and my boating experience will be great this summer. One question is on my air fuel adjustments is that the motor runs great at half a turn out from lightly seated on all three carbs dose that sound like a ok place to leave the air fuel mixture? I am worried about burning it up. But it runs smoothly and responsive there so I think its ok. Things I did to the motor are rebuilt fuel pump. All new fuel lines rebuilt and cleaned carbs and set the float hight and new carb gaskets big thanks again im a happy camper now