View Full Version : 78 Mercury 80 hp troubles

August 27th, 2006, 01:40 PM
I have a Mercury 80 hp, 1978 model, on my 76 galaxie. since I bought it earlier this year, it has been extremely cold natured. its easy to start when you choke it, but doesnt want to stay running. after 10 to 15 minutes of fighting with it, it will eventually run alright. Once you get it to this point, it will jump right up on top the water and run as its supposed to. Even after its been used for hours, turn it off,, and it takes 10 to 15 minutes to get it up and going again.
Ive cleaned the fuel tanks, replaced the fuel line and primer bulb, and removed the carburators and given them a good cleaning. there was no trash in the carburators when I removed them, so I sprayed them out with carb cleaner, and put them back on the motor. out of water, hooked up to my water hose, it starts and runs fine. no cold naturedness at all. in the water, when the motor has a load to fight with, the above described problem re-appears. in addition to the work ive done on it, before I bought the boat, the entire ignition system was replaced in the motor by a qualified mercury mechanic, whom ive known and trusted for years. He has told me that some of those older mercury motors are just like that, but this doesnt sit well with me. there has to be a solution. what other areas could I look at on this motor to help with my problem? thanks in advance, this thing has been driving me crazy all summer.

October 8th, 2006, 01:04 PM
I know it is way late to answer this post being posted in August. However a couple of months ago I had the following experience. First last fall, I worked about a month primping the boat. Spent about 2 grand on new radio, color depth finder, 4 new seats, new 80 pound thrust trolling motor and more. Now ready for my week long up north fishing trip with a bunch of other guys and boats as an annual trip north. I went to Canadian boarder in Minnisota with a brand new BIG trolling motor so I could fight the wind while fishing being my big goal. I own a 1987 Skeeter with an 80 horse power merc motor being about 5 years older than that bassboat. Drove 17 hours to get there. Weather was great till we hit the Minnisota line, it started raining at the state line and never quit raining until the last day when we gave up due to snow predicted the next day and went home. When I got to the lodge it was getting late. We decided to do a bit of fishing before supper being a couple of hours for a short but enjoyable start in a week of fishinig regardless of the rain. Launched the boat in the rain. Merc motor started great as usual. Had that motor for 15 or more years no problem, started ran great. Motor warmed up while idling waiting on my partner to park truck and get in the boat. He jumped in and off we went to start our fishing trip. Went about 1/2 mile across lake and the motor just shut off while planed out. Restarted the motor thinking just a lark. Motor idled a bit then give it gas and died. Went back to shore and loaded the boat. Checked the boat over. Of coarse cleaned the carberator before checking anything else. No good. Checked for spark, aha, no spark. Electronic ignition dead as a door nail. Nowhere within 100 miles the buy electronic ignition for a motor that old they said. Fished for a week with that fast trolling motor and had a ball all week in the rain and then to snow. Went home with a good feeling. Change the electronic ignition and I am good to go. I knew five years ago that the manufacturer recommendation for that motor's compression was 100 pounds per cylinder. 5 years ago it measured 90 pounds per cylinder but it ran great. Why fix what isn't broke is my mind set.

Got home and got busy till about July. Found a new electronic ignition and replaced the bad one. Put a hose to the motor and tested it. Started great as usual. Revved up to high speed a couple of short burst and worked fine. Ready to go fishing again.

In July or early August I found a new girlfriend right under my feet where she hid for years. She claimes I asked her out and even brought her a flower on our first date and behaved myself. Yea right that is her story ? Maybe that was right but never admitted that part yet. I really wanted to show her a good time so about a month later I took off on a trip to Alabama Guntersville lake for the first time with my brand new girlfriend ! Drove after work till 2 am and arrived, rented a motel to go fishing reasonably rested in the early morning. Really needed to impress this new picky girlfriend and wanted to show her a fast trip across a really big empoundment then catch lots of big fish.

Now the big fishing horror story starts !!!

What happened was I launched the boat, loaded all the goodies, started the motor and it warmed up great. Untied the boat from the dock and put it in gear and it died. Restarted and put it in gear and it died. This was a repeat story for about 30 minutes till I decided something was wrong. Loaded the boat and pulled it into the city park along the lake in the shade. Took off the carbs to check then as usual the first thing I always did. Found a gasket not quite right. Asked Lisa to watch the boat while I went for new gaskets. I disconnected and drove off leaving her RESPONIBLE FOR THE BOAT till I got back. She said I no sooner went around the curve and the boat took off by itself on the trailer for the lake and a great big tree. She just stood there with her mouth hanging open and her arms in the air and watched my boat take a trip by itself. The boat motor skag hit the dirt and stopped the boat by plowing a furrow in the gravel about 10 feet just before the boat hit the tree. I got back and hooked the boat back up and pulled it back to level ground in the shade. Repaired the carbs and was ready to launch the boat again. Got it in the water and same thing idled great but motor would die the minute you put it in gear. Decided it was idling too fast. Worked in the sun for about 4 hours trying to idle down the motor so it wouldn't kill the motor the minute you put it in gear. Then gave up and headed to the motel. Told Lisa hang the gas motor we still had a big trolling so we would go fishing with trolling motor only at daybreak.

Early morning we hit the ramp in pitch dark. Launched the boat. Pulled it by rope back to the ramp and asked Lisa to watch the boat while I paid the launching fees at Goosepond Colony. Took five minutes to pay and get back to Lisa. Turned on the flash light and said this is not good. Lisa said what I pointed at the boat. The boat was half full of water. Now she blames me for sinking the boat just because I forgot to put the plug in the boat but everyone knows she was in charge of the boat I wasn't even there when it filled with water !! I waded through the water and put the plug in the boat, turned on the bilge pump and said lets go fishing. She pointed at the water in the boat. I told her to trust me because the bilge pump was pumping it out. At this stage in the trip you would not believe the look I got from her before she stepped into the boat. Who would figure out women ?

We took off with our fast trolling motor and started fishing. Got over by the outdoor stage and picked up a nice 8 pound large mouth for my first AND ONLY fish of the week. She was impressed !!! So was I. We got trapped in some moss so we had to work around the moss so we didn't damage the bed. Got into the moss some but when we got to open water I hit the trolling motor on high. Yep I watched the prop of the trolling motor float to the bottom of the lack without a back up prop and with a broke gas motor. We sat there a short while. Watched a boat out on the river go flying by. I told Lisa that I USED to go that fast. She just laughed out loud. Better than crying.



October 8th, 2006, 01:06 PM
Nope story not over yet.

A local guy saw us flagging and hooked on to tow us back to the ramp. Now he is a fisherman we should be proud of, fish were biting and he helped a fellow fisherman stranded without power. He towed us to the ramp. I thanked him and took off my shoes to step out of the boat and pull the boat to the ramp water line. Yep stepped out of the water and went totally under the boat when I hit the moss on the ramp. Lisa said that was the funniest she had seen watching me sit and push sit and push trying to get up that ramp to dry ramp edge.

Loaded the boat and headed home I had had ENOUGH !!!

Got home first thing I did was check the compression of that motor suspecting that to be the problem. Yep the manufacturer says minimum compression is 100 pounds per cylinder. My test showed 50 pounds per cylinder. Cost said replace that old motor rather than rebuild in my mind.

Did the only logical thing. Bought a BIGGER AND FASTER BOAT. Now that hurt my pocket book but I got what I wanted. 20 foot, 200 hp merc, about 5' wide new trailer, new trolling motor and all the other things that go with a new boat not limited to licenses and registration.


Went back to Canadian border with my brand new bigger and faster boat with a much more empty bank account. I was proud of my spotless boat. Boat worked great and had a great time. Problem is I parked at a metal boat dock that had a little piece of steel sticking out at the water line. When I went fishing the SECOND DAY in my brand new bass boat I caught that steel piece sticking out and now have a 2' long scratch along the side of the boat.

Now my brand new boat is used ! I just mentioned that my boat is now used and should start thinking of buying a BIGGER AND FASTER NEW BOAT AGAIN and Lisa showed her first sign of taking charge. Guess I am going to have to live with my BIGGER FASTER USED BOAT now. She is afraid that if I buy another new boat due to the scratch marring my used boat she might get real hungry. Now to a true fisherman the choice would be feed your girlfriend or buy a nice new BIGGER FASTER BOAT ? You can decide my next decision. Boy I really might miss her if I do what I need to do in the name of fisherman world wide. I think they wrote a song about that.

Oh one last thing. Lisa was watching me write this and I just got hit a love tap of course.


Just to let you know Lisa got even. She suggested my hosting a 30 kid sweet sixteenth birthday party, boys and girls, for her daughter. One of those sweet girls mentioned to Lisa something about hitting me in the face with a piece of the birthday cake. Instead of my sweet girlfriend saying to that young child "No that would not be nice to Warren" She said " Wait a minute let me get the camera. She took a video of this girl viciously attacking me by hitting me not only once with a piece of birthday cake that glued my eyes shut but also picking up the whole cake and heading for the living room with it. I ran to catch the cake and rounded the corner only to get the whole cake in my face a second time starting a 30 kid food fight from my kitchen through dining room then through my entire house including upstairs in my game room. That girl was slick she suckered me. I will say those kids jumped in to help clean up my house where cake was stepped on into my carpets. I talked to the kids later telling them never to try that food fight at anyone elses homes or they would be in big trouble.

Lisa is still laughing !!

To answer in short the quest for this post buy a new motor or a BIGGER FASTER BOAT.

My girlfriend, Lisa, has read this post and reluctantly approved of its content.

She claims she has a different story of the same activity. Who would figure.

Hope you enjoyed