1987 Sea Ray 260 hp 5.7 Mercruiser cranks but won't start

[OHfishing]

Bought a boat having some trouble , I will start at the beginning so you can get a better idea of what may be wrong. Thanks to anyone who helps.

Found a boat last fall , it was still in the dock at a local inland lake. I liked the boat and I noticed the owner took very good care of the boat. He started it right up and we took it for a test drive, everything was perfect. I made an agreement to purchase the boat and he made an agreement to have his marina fully winterize it.

I would also like to add that the previous owner has kept in touch with me since the purchase and is willing to help with all my questions. This guy has no surprises, he has contacted me several times this spring to see how it's going. He is confident he sold me a good boat.

That being said onto the problem.....

I made arrangements to dock the boat at Lake Erie and began getting ready for spring. I started the boat with muffs in the driveway and it started right up but sounded rough. I noticed there was less than 1/4 tank of gas in it (that I know was treated for winter) so I towed the boat to gas station and put in $75 in fresh gas. Upon returning home I tried to start the boat it turned and turned and wouldn't start.

So I postponed the trip to the dock to get it figured out. I changed the water separator / fuel filter and filled the new one with gas before twisting it on. I also hit the carb with gumout and the boat fired right up like brand new.

I started the boat for 2 or 3 days including today and it started fine and idled fine each time.

The boats previous owner and I spoke and I mentioned the rough start problem I had earlier in the week and how all was good now. He told me he had trouble once with rough running and the marina took his flame arrester off and cleaned it and it ran perfect and ever since he cleaned it annually. He said after he cleaned it the engine sounded and ran better.

So today I go out and do a little work on the boat starting with the flame arrester, which I cleaned with gumout than hit it with air. It was clean and dry when I put it back on. Also I climbed down in the engine compartment and cleaned the bilge area and installed a new bilge pump. When I finished I decided to start the engine and see if it did in fact sound better.

The engine wouldn't start, turned and turned and turned, wouldn't start. An hour before it started fine,I'm know the flame arrester or bilge pump work I did would have no effect on the engine not starting.

The thought did cross my mind that while I was leaning into bilge area I bumped something? Maybe a harness or something? I did see a red button near the fuel filter I could have bumped?

I'm by NO means an engine mechanic I'm hoping this is an easy one I can figure out (with your help) but as of today I have to postpone the docking until I figure it out. Lake Erie is no place to play with a family and an engine that's acting up.

Can someone please help get me pointed to the problem.

1987 Mercruiser 260 hp
Serial # B582339

 

[alldodge]

Your going to need to go to the basics. If your cranking the motor and it will not start we need to know id it is getting spark and fuel, or neither.

The red button is the 5-amp circuit breaker, if it tripped the motor would not crank

Nexrt time it will not start have a volt meter handy and check to see if you have 12V at the positive side of the coil

 

[OHfishing]

I will check for fuel In carb and spark tomorrow. Thanks for helping

 

[henleyhale]

spent a few years in an automotive service drive, i had a honda brought to me on a flat bed car wouldnt start, they rolled it off and i hit the key the car started up fine, so i called the man and he came and got it, he chatted with me for a few minutes and told me he had just washed his wifes car and then it broke, then a month or so later here it comes on the flat bed again, and again it cranked just fine. When i called him to tell him the news again he had just washed the car, so i pulled it in to the wash bay which was a touch free sprayer and the car died almost immediately, this had electronic ignition so a distributor was out the only thing left was the wires, i popped open the hood and the plug wires were old and brittle all original to a 150k mile car. I had the boys swap them out and dry the plugs then drove it from the wash bay. Im not saying its the wires but intermittent start failures after a previous start and rough running smells like moisture near some old wires to me, and also if im right where is the moisture coming from?

 

[OHfishing]

Just notified from the previous owner that last year the marina changed the dist. cap , rotor , and plugs along with the solenoid and both batterys were replaced , along with the outdrive and bellows and all ball bearings Only thing not changed was the plug wires

Im still checking the cap when I get home, along with the choke and the carb,

thanks again for helping

 

[flipbro]

Try spraying a bit of gas in the carb if it fires up you know its fuel system related. The old rochester carbs like to leak the bowl dry if not run for a couple days.

 

[OHfishing]

Yes Sir that will be the first thing I try

 

[OHfishing]

okay I come home from work before I start to work on the boat I turn the key is starts and runs perfect. Now what?

 

[duped]

Hate it when that happens. I would do a thorough check of all ignition related connections. Clean the terminals of the coil and wires going to it. Apply new liquid tape after.

It may be prudent to order new plug wires and a new ignition sensor now. I've had many issues with 20+ year old wires arcing and raising hell. If the tension wire from coil to distributor cap is bad you get no spark. If the ignition sensor is bad you get no spark.

Last time I had a no start condition it was the latter, and the ignition sensor died shortly after cap + rotor was replaced.

Next time it doesn't start, check for spark. If none, turn ignition to run and check for 12v at the purple wire at the coil. Note, don't measure voltage across the coil. Put the red lead of your meter to the purple (positive) of the coil and black lead to a good ground.

If you have 12v at coil in "run", I would almost guarantee it's the ignition sensor in the distributor. Moisture rusts it up and gives you a lot of crap. Ask me how I know....

 

[OHfishing]

Update , took boat tonmarina today to dock, launch boat won't start. Employee at marina see,s me dead in the water on the ramp jumps in 30 seconds later I'm on my way to the dock.

It was the nylon on the end of the shift cable. I guess it hangs up and kills ignition??? Anyhow problem solved had a great day on lake erie catching a few walleye and waking up some rays

Thanks to all who helped me.
Good luck to you all