140 seahorse dead cylinder FIXED

[mookieo2]

Took it out for a spin the other day. It was the first time for the season. It starts right up. I don`t have a working tack but the boat would only get up to about 19 mph. We can usually get it up to 35 on wot. brought it back to the dock and pulled the plugs one at a time. We found that the lower left cylinder is dead. The spark looked good. It was blue and would jump a decent gap. I brought it home and swapped coils. No change. We tried changing plugs from a working cylinder and no change. Swapped power packs from right to left. No change. Compression is about 115 -120 on all cylinders. I read on here to try cleaning the carbs. I didnt rebuild it but I removed the lower one and sprayed carb cleaner in all jets removed the bowl. The needle valve is working. checked with compressed air and watched the float move up and down. Blew everything out with compressed air and reinstalled. Started right up and no change. I sprayed carb cleaner in the running motor and it didnt sound any different with the lower but when sprayed in the top carb the motor would bog.

What should I check next or re check that maybe I didnt do correctly.

 

[emdsapmgr]

Re: 140 seahorse dead cylinder

Re: 140 seahorse dead cylinder

What year engine?

 

[mookieo2]

Re: 140 seahorse dead cylinder

Re: 140 seahorse dead cylinder

What year engine?

I believe its an '82

 

[emdsapmgr]

Re: 140 seahorse dead cylinder

Re: 140 seahorse dead cylinder

Did the plug look wet or dry? (getting fuel or not..) Any chance that you are getting some water intrusion into that cyl? The plug might look milky. Water, in sufficient volume, can kill combustion even though you have spark and fuel. Common on the bottom cyl.

 

[mookieo2]

Re: 140 seahorse dead cylinder

Re: 140 seahorse dead cylinder

Correction it is a '79. Today I started over. I decarbed the motor according to the secret file with Seafoam. I also bought a spark tester. It is not an adjustabe one. It was all Autozone had. It looks like a spark plug with a spring clamp on it.

After the Decarbing. I put in new plugs, started it it up, and ran it for a while. This was all done out of the water. Its a pain to trailer the boat 20 min to the dock and the problem isn't only when under load. I pulled the plugs and they all looked good one was a little darker than the rest but that one isn't the dead cylinder. I did a compression check, Three cylinders were 107 and one was 120( the darker plug) so the compression is lower than normal I think, but relatively close to each other.

I did the spark test. This time I noticed that the dead cylinder had a week spark. It would spark through the tester but it wasn't as consistent as the others and not as bright.It was maybe 1 spark to 6 of the working cylinders. I swapped leads on the power pack and there was no change.

I am going to pick up a new coil tomorrow and if the spark is stronger I'll water test it.

Is the compression ok or is the motor a gonner? If I fix the dead cylinder I can probably just run it till it dies however long it may be.

 

[emdsapmgr]

Re: 140 seahorse dead cylinder

Re: 140 seahorse dead cylinder

Swapping the ignition coils is a good way to test them. Also, have a good look at the wires make sure they are not arcing to ground or the lower cowling latches. When new that engine would probably have had 130+ lbs compression on each cylinder. A second decarb might not hurt. You can continue run the engine the way it is if the all the rings are still intact and if there is no aluminum transfer from the pistons onto the cylinder walls. You'd probably have to pull the heads to check.

 

[mookieo2]

Re: 140 seahorse dead cylinder

Re: 140 seahorse dead cylinder

Update from today.

Decarbed again. Compression check 110psi on 3 of the cyl 120psi on the 4th.

Replaced bad ignition coil. Started motor up and noticeably smoother.

Water tested it. I couldn't get it to idle at first. I adjusted the throttle cable a little and it would now idle and go into gear without stalling. It would not let me give it throttle in gear. I could go a little over idle speed and then when I gave it more throttle It would stall every time. It seemed like there was more fuel than normal when I revved it in neutral floating in the water.

Did decarbing it maybe disturb something in the carbs? I'm sure it cant hurt but if I rebuild the carbs and replace the fuel lines would that fix it? I don't want to put too much money or more time into this thing.

 

[mookieo2]

Re: 140 seahorse dead cylinder (Fixed)

Re: 140 seahorse dead cylinder (Fixed)

Well its fixed. The coil was the main problem but I guess fooling around with the carbs must have done something. I rebuilt the carbs, fuel pump, new fuel lines. It was well worth the $60 and a few hours. The boat runs great. I'm going to try to do the Link n Sync when I get a hold of a timing light.

Does anyone else have the problem with the new style coils? The cover rubs on the boot. I had to swap coils to move it to the upper cylinder because the latch was rubbing and would have made a cut in the boot if I forced the cover on.