1979 80HP Mercury, not running.

[sramelyk]

Ok.. For 3 years I have been working on this motor. I have replaced 2 coils and the "switchbox". Last year it ran but had no power. After pulling out the plug in the bowl of the top carb I realized it was not getting gas to the top carb. I pulled the bowl off and the needle valve was stuck. I replaced and it ran fine the last 2 outtings last year. This year it started up fine on ears.. And ran great the first tryout trip to the lake. About 1 week later we went camping and I put it in the water and it was hard to start. After it finally started it didn't have any power. I seemed identical to the problem I had last year so I pulled the bowl off and the needle valve was stuck again. I loosened it up and sprayed some carb cleaner in it.. It started and ran great for about 15 minutes.. I was pulling my daughter on a tube runnning almost wide open and it just stopped running. It took me about 15-20 minutes to finally start it and it ran at high idle for about 30 seconds and died.. I pull the bowls off and I am getting gas to the carb.. I have spark on all four plugs.. The plugs weren't in terrible condition but I cleaned them with carb cleaner.. It takes quite a lot of coaxing to get it to even start, and like I said.. Once this happens it only runs for about 30 seconds.<br /><br />Any and all help would be greatly appreciated.. I am to the point of rebuilding the carbs, but want to make sure I am not overlooking something else simple first.<br /><br />Also.. When it dies after that 30 seconds it almost sounds like its gasping for air, like its built up a vaccum.<br /><br />Thanks in advance for the help!!

 

[roost]

Re: 1979 80HP Mercury, not running.

Have you checked your fuel pump? The main jets might also be partially pluged.

 

[sramelyk]

Re: 1979 80HP Mercury, not running.

I replaced the fuel pump last year.. I doubt its that.. And I am definitly getting fuel into my bowls.. Something I forgot to mention earlier.. I have fuel dripping from somewhere.. I can't see where but its definitely dripping in the water.. Its odd because it ran great. Then suddenly just died.. Almost seems like something lodge in somewhere.. If the main jets are plugged will gas leak from somewhere?

 

[roost]

Re: 1979 80HP Mercury, not running.

The main jets wont make it leak fuel. The needle valves if stuck open will make fuel leak. When this happens have you pulled the plugs to see if they are wet or dry?

 

[sramelyk]

Re: 1979 80HP Mercury, not running.

Not really right after. But in troubleshooting on the lake I did pull them out to see if they were in bad shape.. And to be honest.. They all seemed dry. But not totally sure.. I will check tonight. At this point I am pretty darn sure its carb related, and am just to the point of rebuilding them anyways.. <br /><br />And I am not sure were it is leaking fuel, and it isn't a tremendous amount.. But if I am sitting there trying to start it I will definitely build up an oil ring in the water by my motor.. I can also watch it drip occasionally off my motor.. But don't see it coming from the carbs, although I assume that is is.. <br /><br />If the needle valve is stuck open, would that prevent the motor from starting?

 

[sramelyk]

Re: 1979 80HP Mercury, not running.

Some things I did tonight.<br /><br />I replaced spark plugs and reaffirmed spark.<br />I pulled lower carb off and with the gasket in place. I replaced needle valve and spayed out all the holes with carb cleaner.<br />I then replaced carb back on the block and checked for fuel leaks, which weren't present.<br /><br />I tried to start and pretty much the same.. IF I coax it it will start and run sometimes a few seconds sometimes up to 15-20 secs.. Usually not starting again for awhile. <br /><br />The gas appears to be coming out of the large hole in the front of the carb, in both carbs.. Maybe flooding. <br /><br />I know removing and replacing the carb without gaskets isn't good, but I wanted to try and keep from putting money were it didn't need to be. I have 2 carb kits coming in tomorrow and I plan to rebuild the carbs then. However, I am just wondering if its going to do any good.<br /><br />Anyone else have and suggestions or ideas on other things to check first?

 

[laker925]

Re: 1979 80HP Mercury, not running.

I'd do a rebuild and recheck the float and that the settings on the needle and seat are measured as accurate as possible even that the clearence with it upside down(after removal) is correct.That is a start.I had trouble once with mine doing that and as it was starting to die I kept pressure on the fuel line bulb as it started to die and that kept it alive-I knew then it was a problem with the carb fuel settings.

 

[sramelyk]

Re: 1979 80HP Mercury, not running.

I really didn't see that the carbs looked varnished or dirty at all.<br /><br />There is a plug on the front of the bowl on my carbs. According to my manual this is where the main jet is, or this is the main jet.. Should I soak that whole plug, or remove the jet and soak everything. Does anyone having any tips on cleaning and or rebuilding the carbs?

 

[sramelyk]

Re: 1979 80HP Mercury, not running.

Well. The kit this marine place ordered wasn't even close.. Not sure what happened there.. <br /><br />Anyways.. I went to napa and ordered a gasket kit, which will be here tomorrow.. Do I need to replace anything else? Jets or anything? I had new needles and seats which I installed over the weekend hoping for a quick fix..<br /><br />Should I just pull the carbs off and clean them really good? And what does this entail? Pulling the idles screw and jets out and soaking? Or scrubbing and running some small wire through?<br /><br />Sorry for all of the questions.. Just seems to easy.

 

[sramelyk]

Re: 1979 80HP Mercury, not running.

Some things I have been thinking about.<br /><br />Last year I had a needle valve sticking.. Which meant only 1 carb was working, and the motor ran just didn't have any power. Now, I no both carbs are getting fuel, and if 1 carb all of the sudden got clogged, wouldn't the other one still work. I would be amazed if both got clogged at the same time. It still blows me away that the engine just doesn't start most of the time.. Then I confuse myself and think well, it does start sometimes and runs for a bit then dies.. Which leads me back to fuel.. AHHHGG!!

 

[jamesr1]

Re: 1979 80HP Mercury, not running.

Try squirting some gas into the carbs. It should run for a few seconds and die. Repeat this process several times. If it starts right up after squirting gas into the carbs, and you are getting gas into the bowls, then the jets are probably clogged. I am just a shadetree so maybe someone else could verify this.

 

[sramelyk]

Re: 1979 80HP Mercury, not running.

OK.. Tonight I pulled both carbs off and cleaned very good with carb cleaner.. Completely disassembled and soaked. Adjusted float level which was pretty far off. Re-installed and it ran nice for about 3 minutes.. I tried squirting a gas/oil mixture into the throat of both carbs and nothing. <br /><br />I then checked my spark again. At first on coil 1 I didn't get anything.. Then 2 was very weak.. I went back to 1 and I had a nice spark for maybe 2 or 3 engine revolutions, then nothing. 3 and 4 were about the same.. When spark was present it was very weak.. I replaced my switchbox last year and when I bought the boat either the stator or trigger had been replaced because the wiring harness was brand new.. I guess I need to refocus on electrical.. Any suggestions on that?

 

[sramelyk]

Re: 1979 80HP Mercury, not running.

Ok.. False alarm.. I am getting good spark to all four plugs and it's purrin' like a kitten. I had my cowel unbolted which also included 2 braided ground wires.. Once I tightend those up it I couldn't keep it from starting while trying to check for spark.. Thats a damn good feeling.. <br /><br />Thanks for the help.. Looks like dirty carbs..<br /><br />A special thanks to jamesr1..