Force 50 Coughing

[markh28]

Force 50hp, 1988, 507Y8D

Using my DVA meter I determined I had a bad trigger. Changed that, had to make some throttle cable adjustments and throttle linkage adjustments to get it to run right since it was running on 1 cylinder for so long. Now I have spark on all cylinders but it is jumping/coughing every 10 seconds or so. It does this in neutral and in gear. I have included a link to a short photobucket video showing what it is doing.

Note on the video that the first "cough" occurs at 10 seconds in, then at 22 seconds, then about 39 seconds.

I have set the idle mix according to the specifications in the Force factory manual.

Photobucket link to video:
http://s298.photobucket.com/albums/mm270/markh28/Misc Boat/?action=view&current=VID00004.mp4

 

[john from md]

Re: Force 50 Coughing

It appears to be backfiring which usually indicates a lean mixture or timing too far advanced.

After you rigged it, what did you set the timing at? Also, have you cleaned out the fuel recirculation system?

 

[markh28]

Re: Force 50 Coughing

I did not clean the fuel recirculation system. Although I rebuilt the carb and fuel pump including diaphragm and check valves. As far as the timing, the only thing the factory manual said was make sure the timing mark was lined up when the #1 cyl was TDC otherwise you have a sheared flywheel key. Well the flywheel key is not sheared because I had it off a few times in this whole process. All the other timing adjustments in the manual have to do with WOT and I cant do that at home. But that wouldnt affect the idle anyway would it? When we replaced the trigger I tried to make sure that the timing arm was in the exact same position as the old one was when it came off but do you think the timing adjustment arm is messed up? Would that cause this problem?

 

[markh28]

Re: Force 50 Coughing

OK I fixed it. I disconnected the timing linkage and started it and let it idle. It was still coughing every once in a while, so I pushed the timing arm in just a little bit...after moving the timing arm it stopped spitting. I think my timing arm must have just got out of alignment when I put the new trigger on. Must have just had the trigger slightly out of position.

 

[john from md]

Re: Force 50 Coughing

Sometimes it only takes the timing to be off a little bit to throw things out of kilter. Glad you got the problem solved.

 

[blueoval78]

Re: Force 50 Coughing

Hello, I'm having the exact same problem, how did you adjust the timing back to normal?

 

[john from md]

Re: Force 50 Coughing

Blue oval, do you have a manual for your engine? If not, the first thing you need to do is buy a Clymer Force Outboard Shop manual. It is too difficult to try and explain timing and carb sync from a keyboard.

 

[jason32038]

Re: Force 50 Coughing

OK I fixed it. I disconnected the timing linkage and started it and let it idle. It was still coughing every once in a while, so I pushed the timing arm in just a little bit...after moving the timing arm it stopped spitting. I think my timing arm must have just got out of alignment when I put the new trigger on. Must have just had the trigger slightly out of position.

Make sure those cheap plastic timing linkage connectors arent stripped or cracked.

 

[blueoval78]

Re: Force 50 Coughing

After reading several posts concerning "coughing", I am not sure now if I have a timing or idle mixture problem? Many people with a coughing issue have indicated that the mixture is possibly too lean?

I guess to further describe my problem, my motor is doing the exact same thing as the video markh28 posted but it also seems to be idling a little high. It does start no problem hot or cold though and I have no issues accelerating or at WOT so I am unsure of what each problem presents itself in terms of symptoms.

Any ideas?