'84 inline 6 - won't accelerate

[vermonter]

Hey guys, I have a "new to me" inline six on my MFG 18 footer, seems to idle fine, but when you hit the gas, it starts to bog out - won't actually stall, but won't power up. Fuel is fine since if you remove the plugs after such an event, they're wet. Also, I replaced the plugs and wires as routine maintenance. I thought it was out of time, and it was, but it is timed now and still the same. Also, when it's bogging, it will intermitintly rev up as if some missing cylinders suddenly fire for a few turns. Compression is the same for all cylinders and good. Should I be testing the Stator, the coils or the power boxes (switches)? Thanks.

 

[lilmandavis]

Re: '84 inline 6 - won't accelerate

coud be a bad trigger. put spark testers and see if thier all fireing or which ones aint.

 

[chunt006]

Re: '84 inline 6 - won't accelerate

Check the carb floats to see if they are stuck or full of fuel. I had one float that had a hole in it. It idled fine but would not rev up.

 

[Chris1956]

Re: '84 inline 6 - won't accelerate

vermonter, If you have spark on all six, then is is likely the carb set-up. Those motors needed a rich idle mixture in order to rev up. Of course the motor ran better at idle with a lean mixture. A compromise between rich for go and lean for idle is what it needs.

 

[vermonter]

Re: '84 inline 6 - won't accelerate

Wouldn't sqeezing the ball or spraying starting fluid in the carbs make a difference when you accelarate if the fuel system had anything to do with it? There's no apparant difference when these actions are taken. Also, the stator tests okay with the ohm meter. Thanks for your input.

 

[Chris1956]

Re: '84 inline 6 - won't accelerate

Vermonter, I do not recommend spraying starting fluid into the motor at any time. They catch fire pretty easily (like almost everytime), and it is bad for the motor. You can try hitting the choke button momentarily when it starts to bog. It may work well enough to get you on plane.

Pumping the bulb should not have an effect, since the carbs are full.

 

[Bob_VT]

Re: '84 inline 6 - won't accelerate

Did you do a linc & sinc? Look in the engine FAQ section and read the post towards the bottom Timing and Sync of Merc Inlines (to 1988)
Follow those directions to the letter.

Welcome fellow VT'r.

Drop me a line at rpf924 at hotmail
Bob

 

[webster101]

Re: '84 inline 6 - won't accelerate

Hey guys, I have a "new to me" inline six on my MFG 18 footer, seems to idle fine, but when you hit the gas, it starts to bog out - won't actually stall, but won't power up. Fuel is fine since if you remove the plugs after such an event, they're wet. Also, I replaced the plugs and wires as routine maintenance. I thought it was out of time, and it was, but it is timed now and still the same. Also, when it's bogging, it will intermitintly rev up as if some missing cylinders suddenly fire for a few turns. Compression is the same for all cylinders and good. Should I be testing the Stator, the coils or the power boxes (switches)? Thanks.

 

[webster101]

Re: '84 inline 6 - won't accelerate

Hey guys, I have a "new to me" inline six on my MFG 18 footer, seems to idle fine, but when you hit the gas, it starts to bog out - won't actually stall, but won't power up. Fuel is fine since if you remove the plugs after such an event, they're wet. Also, I replaced the plugs and wires as routine maintenance. I thought it was out of time, and it was, but it is timed now and still the same. Also, when it's bogging, it will intermitintly rev up as if some missing cylinders suddenly fire for a few turns. Compression is the same for all cylinders and good. Should I be testing the Stator, the coils or the power boxes (switches)? Thanks.

please post what was correct repair I have been trying to fix same prob in my "85" inline 6 for 2 years!

 

[emckelvy]

Re: '84 inline 6 - won't accelerate

It's most likely the stator. I had one with similar symptoms.

Check the resistance of the red-blue and red-white/blue-white charge coil windings in the stator and if the resistance values are out-of-spec replace the stator.

If the stator checks out perfectly, then move on to the trigger and other ign components including physical inspections of each coil for cracks. You'll need to remove the coil from its holder to do this.

I used CDI replacement stator which has an internal voltage regulator and exposed coils for cooler running. Worked like a charm.

www.boatfix.com has a CDI link and decent prices on the replacement.

Here's some other useful information:

http://outboardparts.com/mercury/troubleshooting/troubleshooting10.htm

BTW there have been recent stator replacement/troubleshooting threads so I'd suggest using the search feature, keyword 'stator' should pick up lots of results.

Here's one example:

http://www.iboats.com/bbboard/bbBoard.cgi?a=viewthread;fid=29;gtid=1140807

HTH............ed

 

[vermonter]

Re: '84 inline 6 - won't accelerate

The resistance on the stator checked out, so I checked the coils, it appeared that 3 coils were bad, and I replaced them ($$$ ouch) however, only one was actually bad, the other two were caused by the top switch block - which when replaced seems to fix the mis-firing problem. (this is an old motor and new to me, it appears that there was little maintenance on this baby.) So, now I will take it back in the water to see if I've solved the acceleration problem and re-adjust the mixture screws. I'll let you know what happens.

 

[vermonter]

Re: '84 inline 6 - won't accelerate

No go. It idles like a charm. good spark on all cylinders, messing with the idle mixture screws doesn't seem to make a difference. Guys, I've tried adjusting the idle mixture screws as they say in the manual, and I don't get something: when I back out the needle, it is supposed to eventually cause the cylinders to miss, however it never does this... is this indicitive of some other problem in the carb? - of course too lean a mix does cause the cylinders to start missing. Thanks again.

 

[vermonter]

Re: '84 inline 6 - won't accelerate

please post what was correct repair I have been trying to fix same prob in my "85" inline 6 for 2 years!

I'll let you know - 'course I'll have to fix 'er first! d

 

[vermonter]

Re: '84 inline 6 - won't accelerate

Vermonter, I do not recommend spraying starting fluid into the motor at any time. They catch fire pretty easily (like almost everytime), and it is bad for the motor. You can try hitting the choke button momentarily when it starts to bog. It may work well enough to get you on plane.

Pumping the bulb should not have an effect, since the carbs are full.

Pushing the choke cause it to stall unfortunately.

 

[Bob_VT]

Re: '84 inline 6 - won't accelerate

Did you follow the linc and sinc instructions? Usually when you adjust the carbs you turn the idle screw in until it coughs then back it out a 1/4 to a 1/2 turn. Do the top, middle, bottom and repeat this about 4 times.

I am working on mine tonight i have a similar problem but I am also going to adjusting my timing too.

Bob

 

[bbarrons]

Re: '84 inline 6 - won't accelerate

Did you do a linc & sinc? Look in the engine FAQ section and read the post towards the bottom Timing and Sync of Merc Inlines (to 1988)
Follow those directions to the letter.

Welcome fellow VT'r.

Drop me a line at rpf924 at hotmail
Bob

Could someone post the link to linc n sync.....cant find it after several searches...thanks

 

[Bob_VT]

Re: '84 inline 6 - won't accelerate

It is located in the Engine FAQ section of the forums. The very first section in the forums here. It covers most inlines and is great info.

I re-did mine tonight and will test hopefully this weekend.

 

[bbarrons]

Re: '84 inline 6 - won't accelerate

Thanks. I had just found it and came back to post.... I wasnt looking up.
here is the link http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=36;gtid=1114512

 

[vermonter]

Re: '84 inline 6 - won't accelerate

Thanks. I had just found it and came back to post.... I wasnt looking up.
here is the link http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=36;gtid=1114512

Thanks - I will try this procedure tomorrow.

 

[vermonter]

Re: '84 inline 6 - won't accelerate

Well, the procedure didn't work, so I've concluded that it is the stator/trigger coils. I have purchased a new trigger for around $50 through ebay (nice find considering retail) and a stator on ebay for $129 including shipping. I know they go bad eventually anyway, and I can re-sell them on ebay if that's not the issue, but I've tried fuel system, replaced a defective switch, 2 defective coils, and it still won't accelerate past a certain rpm. I'm fairly confident that this stator is the issue, as I've read in many places that the stator has a separate winding for higher speeds and I'm willing to bet that the high speed winding is defective.
I'll post the answer when I finally get the new coils on.