starts to misfire after 10 minutes top end

[bshawmn]

1989 85hp Chyrsler Force outboard. Can't read model and serial numbers. Just last year I've had new impeller put in and carbs rebuilt. The engine starts out fine, but about 5-10 minutes of crusing, it starts to misfire, but only above about half throttle. Idle runs fine, up to midrange and then the misfiring starts and she bogs down until I cut off the throttle. I've changed plugs while out on lake, and the misfire is still there as soon as I take off. I'll bring it home, let it sit overnite, and bring it back out and it will start out exactly like the day before. (misfiring about 5-10 minutes into outing). Runs great at full throttle, but only for those 5-10 minutes, then the misfiring starts.<br />Thank you for any help.

 

[Solittle]

Re: starts to misfire after 10 minutes top end

bshawmn - Welcome!!!<br /><br />One of the moderators will move this to the Chrysler/Force section. This section is for non repairs/problems.

 

[JB]

Re: starts to misfire after 10 minutes top end

As SoLittle says. . .

 

[roscoe]

Re: starts to misfire after 10 minutes top end

Ok, first off, 1989 would be a USMarine Force.<br />I suspect from the symptoms, you are dealing with a bad coil, that starts to miss when it gets hot.<br /><br />I'd tell you to just replace all three, but they are about $85 a piece, available at any Mercury dealer. Aftermarket coils are $50 each at maxrules.co m, part number 182-4475<br /><br />You can check them out with an ohm meter and following the test procedures listed in the SELOC repair manual for Force motors, pages 5-31, specs are listed on page 5-44.

 

[vprgtsr001]

Re: starts to misfire after 10 minutes top end

im having the same problems with my '88 force/usmarine 50hp. after about 20 mins or so of perfect running it sounds like it starts to miss then bogs down, it will idle and run up to about 25% throttle ok, but after that it starts to miss. I thought it might have been fuel pump but after taking case off i noticed fuel spitting out of bowl overflow when this happens. next guess would have been coil packs. did getting new coils solve your problem??

 

[bshawmn]

Re: starts to misfire after 10 minutes top end

I will try putting on new coils and see then if this is the problem. thanks for the response.

 

[Zero]

Re: starts to misfire after 10 minutes top end

I have the same problem I just got a rinker with a 75hp CHRYSLER 3 cylinders thought the SN was MG647070 not sure where to find it.<br />I took it out today and ran great for like 1 or 2 hours, at full speed and slow speed no problems. Later at max speed the engine spits and spuders like its going to stall or stop. Lower the speed and all is well..<br />I do need to tell you about the gas I put in. First tank was filled in a can at 27 L and added 500ml oil. then I dumped that gas in the tank that came with the boat it only holds 23l.<br />because the first tank was 27l I had a spare 7 to 9 l left in the tank. I filled that 27l tank again and dumped in another 500ml of oil. I think the problem started after I added the second tank to the boat. Also when at a low speed there is allot of smoke coming out.<br />Have I mixed the gas to rich?<br /><br /><br />

Originally posted by bshawmn:<br /> I will try putting on new coils and see then if this is the problem. thanks for the response.

 

[jss763]

Re: starts to misfire after 10 minutes top end

Check with Standard Magneto Sales Co out of Chicago IL. They carry OEM Prestolite Ignition parts for Force Engines at reasonable prices.<br /><br /> http://www.standardmagneto.com/Marine/forceparts.html <br /><br />Coils are $30<br />Stators are $114<br />CDI modules $70-$80

 

[vprgtsr001]

Re: starts to misfire after 10 minutes top end

turns out i didnt have to change the coil afterall. bought a nice service manual and went through all the tests. found that a few of the wires going from stator and trigger to the coil term. block were broken under their boots at the term block. with the motor running and the vibration god knows if they were touching or if current was arcing across. anyway, i took most of them off at the block cut the old U connecters off and crimped on some new ones. bought a set at ace hardware for like 4 dollars. took her out on the lake past weekend and ran beautifully. before you buy a new coil check all these connection. wiggle them behind the boot and see if it feels snapped. also where the ignition coils connect to ignition module either clean the pin(s) of that connection or cut it out and solder in a new one.