1984 85HP Chrysler Force problem

[jr1wolf]

hello, i dont want to bring my boat to the shop and have it cost an arm and a leg, so any help would be greatly apprieciated.

i have a 1984 85HP Chrysler Force. it sat for over 5 years while i was in the navy. i pulled the tank and flushed it, replaced all fuel lines. pulled the carbs and cleaned them. they were clean being it was run out of gas but cleaned them anyways. i pulled the plugs and cleaned them. it started up but sounded like it was missing. i pulled the spark plug wires and found no rpm change on #2. ran a compression test and all three were good. all three get gas. tried again and same problem. i changed the plug and nothing. so i checked for spark and looks good on all 3. put an ohm meter on the wires and all had same resistance. i tried swiching plugs with different cylinders and nothing. so i then pulled two plugs and started it with only one for each cylinder and it started up and ran with just one plug in each one (using the plug that went with that cylinder). then i put all three plugs back in and its still missing on #2!!!!!!! frustrated. any ideas?

 

[jerryjerry05]

Re: 1984 85HP Chrysler Force problem

Did you check the reed valves?Check the fuel pump diaphram.J

 

[jr1wolf]

Re: 1984 85HP Chrysler Force problem

thanks. it will run on each cylinder seperatly but when i put all three plugs in and pull #2 wire off while running there is no change in rpm like its not firing. if it was a reed valve i dont think it would run on that cylinder by itself and the compression is 135 pounds same as the others. would you have any other thoughts about it?

 

[pnwboat]

Re: 1984 85HP Chrysler Force problem

If the reeds check out OK, then I'd start looking at the ignition system itself.

Double check all electrical connections on the terminal strip below the coil plate. Also check the ground between the coil plate and the engine block. Also the grounds for the coils themselves. Switch #2 and #3 coils to see if the problem moves.

If pulling #2 spark plug wire off still makes no difference in idle speed after switching coils, then switch the CD modules themselves. Each CD module has two circuits. Both are used on the first CD module to fire 1st and 2nd coil, however, only one is used in the second CD module that fires the 3rd coil. Hopefully the second circuit in this module is good. If it is, and the problem is the second circuit in the first CD module, it should work after you swap them.

NOTE: Before you start switching the CD modules, write down the color codes for the wires on the terminal strip. Its very easy to end up causing additional head aches by incorrect wiring.

 

[john from md]

Re: 1984 85HP Chrysler Force problem

If you are getting spark but the cylinder is not affecting operation, then it must be fuel or air. If you have an open carb inlet then the problem is fuel. Check the float level, jets for blockage and the condition of the fuel pump diaphram. A damaged diaphram will act like that.

 

[jr1wolf]

Re: 1984 85HP Chrysler Force problem

pnwboat, jerryjerry05, switched cd moduals and still no rpm change on #2. so i guess im going to go in and check the reed valves but i have to find gaskets first, thats why i didnt really want to check them. could it really be a reed valve if it ran on that cylinder by itself when i pulled #1 and #3 plugs though?

 

[john from md]

Re: 1984 85HP Chrysler Force problem

If you have a damaged reed valve to the point where the cylinder won't carry a load, it will be pissing fuel out of the inlet of the carb. Is that happening?

There are two ways that reed valves get damaged. 1) over revving the engine i.e. running WOT with a 15 pitch prop alot or the engine coming out of the water alot.
2) excessive or violent backfiring. Usually happens if you run the engine out of fuel or have carb problems. Note, I said excessive. Backfiring a few times does not damage the reed valves.

The reeds on these old engines are very strong compared to what they make today. I would suspect reeds only as a last possibility.

John

 

[Mark9740]

Re: 1984 85HP Chrysler Force problem

I had a similar problem with my 85 Hp Force only on the 3rd cylinder. When these guys tell you to look at the fuel diaphram, you need to look at it. I tried everything else and then finally found a tiny 1/8" tear in my fuel pump diaphram. It was flooding the #3 cylinder. Yours could be doing the same thing on the low side of the fuel pump with #2 cylinder. I would've saved a boatload (lol) of $ if I had taken their advice early on. If you're careful enough, you may be able to use the same gasket to put it back togther if it checks out OK.

 

[Frank Acampora]

Re: 1984 85HP Chrysler Force problem

1 You say all three cylinders are getting gas--that eliminates reeds.
2. You say that all three will fire sepately but not when all three wires are connected--that eliminates fuel pump.

Look for a short in the wires from the trigger and stator to the terminal board on the bypass side. If your 84 still has Prestolite quick connects, check for shorts in the wires.
3 since you did switch boxes and the problem still occurred, we must assume that the CD boxes are OK. However, double check the wiring of the boxes to be sure that the top is servicing #1 and 2 and the bottom #3. It is possible for the top to service only #1 and the bottom to service #2 and 3. For an accurate test you need to know before switching CD boxes.
4. If you are not the original owner, it is possible to run these engines on one leg of the stator--simply put, this will only supply half the power to the top box and may cause a weak spark on #2 cylinder. Check to see that both legs of the stator are connected properly and functioning. I have done this as a test on a 90 HP but have not yet tried to run it and check performance.

On 3 cylinder engines both blue wires from the stator are connected together. (Reason: On 3 cylinder engines, the second half of the bottom box is not used and the voltage must have somewhere to go.

 

[jr1wolf]

Re: 1984 85HP Chrysler Force problem

lots of help thanks everyone. im going to put the reed thing to the back burner then and check out the diaphram. i'll let you guys know how it goes.

 

[jr1wolf]

Re: 1984 85HP Chrysler Force problem

wow, well thanks to all the posts it was after all the fuel pump diaphram with a crack in it. im larning a lot now. appreciate all the help im greatfull.

 

[john from md]

Re: 1984 85HP Chrysler Force problem

Just remember to pass on what you learn when others have a problem. That's what makes this list continue to be a great resource to boaters.

John

 

[jr1wolf]

Re: 1984 85HP Chrysler Force problem

thanks john and i will.

now that everything is running great i cant get the idle speed to drop below 1800 rpm. i adjusted throttle arm, cam, and eccentric screw accordinly. could it possibly be the float or float needle in the carb gas pushing through? should i get a rebuild kit for the carbs even though they looked good maybe something i didnt see.

 

[pnwboat]

Re: 1984 85HP Chrysler Force problem

Have you adjusted the idle speed screw on the vertical tower shaft? There is a locknut that prevents the screw from turning. It's kind of hard to see and is sometimes over looked.


Here is a picture from a 1988 125HP motor. It should be similar to yours. The yellow line is pointing to the idle speed adjustment screw.

 

[john from md]

Re: 1984 85HP Chrysler Force problem

Most likely someone adjusted the idle speed screw to compensate for the poorly runnng engine. The screw is located midway on the tower shaft on the right side of the engine.

You may have to adjust your idle mixture screws once you get the idle speed down.

John

 

[jr1wolf]

Re: 1984 85HP Chrysler Force problem

yes i adjusted it. and thanks for the pic. i have the book for it and adjusted to what it said. so i think im going to pull the carbs and double check the floats and needles. i let you know how it turns out. lol

 

[john from md]

Re: 1984 85HP Chrysler Force problem

Nothing in the carbs will cause your idle to go high. The way these carbs work, vacuum is drawn over small holes in the body and this sucks fuel out. The more you open the throttle body, the more fuel and rpm you get.

If you have backed off the idle speed screw and still have a high idle, your basic carb linkage is misadjusted and is holding the throttle plates open. It may be the eccentric stop on the throttle bell crank.

If this is the case, you would best do the entire carb and sync adjustment over from scratch.

Regards,

John

 

[jr1wolf]

Re: 1984 85HP Chrysler Force problem

i just went through and readjusted the cam to the roller on the eccentric screw, and readjusted my tie bar conntecing the carbs. the plates are all the way closed and the cam just touches the roller. so, as is, the carb throttle plates are all the way closed on all three. still idles around 16 to 1700 rpms even after turnig the idle adjustment screw. im lost. this two stoke boat motor stuff is kickin my butt.

 

[john from md]

Re: 1984 85HP Chrysler Force problem

Did you adjust all three throttle plates so that they all close together using the paper test? If they don't close at the same time, one or more will stay open and that will cause your problem.

John

 

[jr1wolf]

Re: 1984 85HP Chrysler Force problem

one of the nut clips on the linkage was kinda stripped out so i put a nut on it. play with the idle adjustment on the carbs and got it to idle down to 1200 rpm. it was wondering if dropping it in the water and putting a load on it would drop the rpm and then igo in and readjust everthing?