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1981 Mercury Classic 50 HP 4 cyl will not run when in gear

Fishingfool1

New member
Hey guys, new to the forum here and I am looking for some help. I have some mechanical training but mainly automotive, no formal marine training but I am a quick study and open minded about mechanical applications. So if you give a reply and I have a somewhat seemingly silly answer or question in return it is only due to my ignorance of marine mechanical terminology and application. I will give as much info as I can and hope I cover everything so no extra questions are needed or at least minimize them. Thanks in advance for your assistance with this.

Note, I replaced the stator and power pack three years ago on this engine. Rebuilt the carbs last year and installed new plugs. I have replaced three coil packs, one was replaced already. I have owned the boat for three years now. I use Startron fuel stabilizer religiously when I add fuel to the tanks.

When running the boat the other day on the way into the landing to go home I noticed the engine skipped and sputtered a few times. I took it home and put the boat up as normal and didn't give it another thought, figured it was some trash or bad fuel maybe. The next week I took it back to the lake and started the boat at the ramp and jockeyed over to the boat slip to wait on my partner to get in after parking and no issues were noticed to this point. He gets in and we idle out of the no wake zone at the landing and everything appears normal. As soon as we clear the buoy's I hit the throttle and it starts to open up as normal and then it stops building rpm's and stays at about half throttle. I return the the lever to neutral and it only gets worse from that point and finally it will not open up at all and stays at an idle only after several attempts to head down the lake. I put it back on the trailer and go home frustrated. When i got home I checked the plugs and they were all good. I checked the spark at the plugs coming from the coils and all have a bright blue spark. The only thing that is noticeable is the engine is idling extremely high now. The engine starts on the first spin and runs at the high(really high) idle but when I put it in gear and give it throttle it will not open up and has a dead misfire and sputters and spits like the timing is way off. While the throttle was down(open), I thought maybe it was fuel related, so I hit the choke button and it killed the engine, meaning it was getting fuel and when I cut the air off it smothered. I checked and there are no air obstructions or visible trash blocking air flow in the carbs. I am at a loss and have no idea which way to go here. Other than start replacing parts, stator, trigger, power pack, ........ Looking for help please and also if testing of components is needed please advise how to test since I do not have normal tools for marine engines.
 
Check flywheel key.----Post compression test numbers.----Have you replaced the water pump impeller ?----Checked for blockage in exhaust housing ?
 
Sorry for taking so long to get back with you. Forgot about the flywheel key but did the others. Cyl#1 - 113, Cyl#2 - 120, Cyl#3 - 125, Cyl#4 - 122, New impeller installed last year, new water housing installed three years ago. Pulled engine apart and did not find any obstructions on the exhaust side, replaced both upper and lower exhaust place gaskets and reinstalled engine. After checking compression found that #3 and #4 spark plugs/coils were firing but were not as good as #1 & #2. Ordered new coils and replaced and it did not change anything, actually less spark now with the new coils. Engine will still start and idle but thats about it. Do you think I got bad coils or is there another issue. Like I said previously I replaced the stator and power pack three years ago. I don't know how to test them or how to tell if they are bad. Flywheel does not spin and I had to wiggle it to get the drive shat splines to line up when installing the lower unit and I did not notice any play or it being loose at that time. Still needing help figuring this issue out. Thanks.
 
Check flywheel key.----Post compression test numbers.----Have you replaced the water pump impeller ?----Checked for blockage in exhaust housing ?

Sorry it took so long to get back but have had some personal issues. Can you see my reply posted on this thread and let me know what you think?

Thanks raceone for the help.
 
Not sure why you would order 4 new coils and then think that you got bad coils.-----Orderly trouble shooting is what needs to be done !
 
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