Mercruiser cuts in and out then dies and wont start. HELP!

[ajone107]

So I took my 1969 Mark Twain out for a ride after it sat for 2 years. It ran great for the first 20 minutes. She was screaming! I had her at about 3000-3500 RPM's and then I noticed her starting to cut in and out and slow down (I could tell she wanted to backfire if i accelerated but never actually did). Then, I found myself barely planing and not accellerating. Finally, it died and then would not start. It just kept turning but it would fire up. I got towed home in about 10 minutes, meanwhile it would not start the whole way up to the dock. Then, I took off the Carb spark suppressor and sprayed a little ether in and she fired right up. I have read a few things on the internet and am not sure where I should look to solve the problem. I know 2 years is a long time for it to sit, so next time I go down im going to empty out the fuel bowl and try to drain all the gas and put some new gas in it. My question, do you think it is bad gas/oil filter? The guy who came to tow me said he saw some gas floating around my lower unit and thought it was some sort of gasket. I am not sure if i feel that is it though. It almost felt as if the boat was flooded, since It would not start.

Thanks,
Adam

 

[SeanMcl]

Re: Mercruiser cuts in and out then dies and wont start. HELP!

I certainly sounds like you got some gunk sucked up into the fuel delivery system and starved the engine. In the Adults Only area there is an excellent sticky on troubleshooting fuel feed issues. It's under "Causes of low WOT", or similar. Lots of other things to look at while you are in there, too.

 

[ajone107]

Re: Mercruiser cuts in and out then dies and wont start. HELP!

Okay, I will look into running something like that test... I am a bit of a novice when it comes to boat repair. Some of it went over my head... Do you think that emptying out the fuel bowl and putting in new fool could solve the problem as well? It also doesnt really talk about where I should go to try and clean things out, or where gunk could be clogging up the system at. I'm sorry im such a noob and really appreciate the help

Thanks,
Adam

 

[Bondo]

Re: Mercruiser cuts in and out then dies and wont start. HELP!

It also doesnt really talk about where I should go to try and clean things out, or where gunk could be clogging up the system at.

Ayuh,...
The Gunk could be Anywhere between the Tank Vent, to the Carb, or Both,+ Everything in-between....

If you're Over yer head, you might need a Mechanic...

 

[ajone107]

Re: Mercruiser cuts in and out then dies and wont start. HELP!

I mean...it just sounded pretty complex. Its a 1969 mark twain, my dad says either get it running or hes donating it to charity :-( The boats been our family for years. It is not an option to take it to a mechanic, I am the mechanic lol.. However, I have done numerous things to it in the past including dropping the lower unit to replace this little plastic tube that got melted and was causing it to overheat. I'm not mechanically illiterate, but I have never had to do anything to the fuel system like it said to in the ADULTS sticky. However, if you guys feel bad gas is most likely NOT my problem, then I will attempt it. Also, I have been working on watercraft mildly and going to the lake since i was a kid, now that I am getting older I should probably learn more about them.. I was just hoping it would be something really simple such as bad gas or fuel filter..

Thanks,
Adam Jones

 

[Dobb15]

Re: Mercruiser cuts in and out then dies and wont start. HELP!

If i where you i would clean my carb out and disconnect all my lines and blow then out with compressed air ... if you put new gas in then there shouldnt be an issue, if you didnt i would drain it then refill with new gas and then retry it. simple way to narrow it down. and buy a new fuel filter.

 

[Bondo]

Re: Mercruiser cuts in and out then dies and wont start. HELP!

but I have never had to do anything to the fuel system like it said to in the ADULTS sticky.

Ayuh,.... Well,... I guess Today is your Lucky Day,....

The Problem is found by Diagnosis,....
I'd start with a remote tank,+ fresh gas,... If it Runs,...
The Problem is the fuel/ tank side...
If it Don't,...
It's the fuelpump/ carb side....