2.5L quit after 45 minutes running, restarted after cooling down, running rough

[motoman701]

I'm pretty handy but due to young kids usually have a hard time finding time to diagnose mystery issues like this, and looking for help with a diagnosis direction

The only maintenance item I did before spring start-up was a new fuel filter below the pump (I did the usual oil changes in the fall). We were on the water maybe 1/3 throttle for about 45 minutes just easy cruising. Throttled up and down a few times. Temp and pressure gauges all reading normal, or at least not spiking (145 deg, can't remember pressure gauge reading). Very quick engine stutter but ran fine for 20 seconds more at about 1/2 throttle, then died very quickly. Tried restarting but wouldn't, gave it a few minutes and it started hard but got it going. Got up to half throttle intending to get back to shore but 10 seconds later died quickly again. Hailed someone down, thought a tow was coming for 25 minutes, nobody was actually coming and tried starting again and it started a relatively easy this time, went 1/4 throttle for 20 minutes back to shore, got it to the dock and it's not running super rough but just feels like it's skipping a little. Powered down and towed home, havn't done any diagnosing since

Any suggestions on where to start? I've been reading around and found possible causes of bad ignition coil, need a fuel pump rebuild, or vapor lock.

Thanks for any help you can provide. Even though I'm handy, because of my wife's anxiousness of getting stranded again I am likely just going to be handing it to a marina to let a pro handle it for her peace of mind, but I'm very curious if I can solve this myself

 

[Scott Danforth]

its never the coil

look at the fuel system, primarily the carb and crud in the tank.

 

[nola mike]

Not vapor lock either. Wouldn't start with the fuel pump, but check the clear sight hose coming from the fuel pump to the carb (should not have any gas in it).
As Scott said, crud/water in the tank, and now maybe in the carb. Do you have a water/fuel separator?

 

[motoman701]

Not vapor lock either. Wouldn't start with the fuel pump, but check the clear sight hose coming from the fuel pump to the carb (should not have any gas in it).
As Scott said, crud/water in the tank, and now maybe in the carb. Do you have a water/fuel separator?

It's not installed yet but I bought a fuel/water separating filter over the winter sitting on my work bench. I had half a tank of ethanol fuel + stabil over the winter in the boat, the other half empty (Northeastern US) which looking back was a mistake. I filled the remainder with non ethanol just before this trip out to the lake. Add this to the call I got from a mechanic asking me these same questions, I think I'm in line for a pump-out and refill plus having my carb cleaned. *facepalm* I mentioned I'm a boating newbie in my signature haha

 

[nola mike]

Most of your fuel is probably fine (though I'm sure many would opt for a total pump out). I'd first drain your carb bowl to see what's in it, and/or disconnect a fuel line and see what you get. Also recheck your fuel filters at the carb inlet and the fuel pump, see if there's crud in there. Water will be on the bottom and will separate out in a clear container. I've had water in the tank before; I was able to siphon through the sender hole a few gallons from the bottom of the tank. Kept repeating till I had clean fuel coming out. I actually was able to then separate the gas from the water and used it in my truck, lawnmowers, etc.

 

[motoman701]

Thank you nola mike

 

[motoman701]

Update: had a phone conversation with a mechanic who seemed pretty knowledgeable. I actually dropped the boat off tonight but he can't look at it for a few days. He thinks it's the coil, with me describing that the engine having died all of a sudden instead of stuttering and dying, and then being able to start it somewhat easily once it had cooled off 25 or so minutes later. I already have a Pertronix and high performance coil I planned on installing anyways, so I'm going to try that and see how it goes. Mechanic is cool with me nabbing the boat back and doing it myself and bringing it back if it's still acting up

 

[Bondo]

It's not installed yet but I bought a fuel/water separating filter over the winter sitting on my work bench.

I already have a Pertronix and high performance coil I planned on installing anyways, so I'm going to try that and see how it goes.

Ayuh,.... The fuel filter is a necessity with todays ethanol fuel, 'n a very important diagnostic tool, if you examine the contents of the take-off filters,.....

Looks like yer gonna be busy,.....

 

[motoman701]

New update. I spent 2 evening getting electronic ignition and flamethrower coil installed. New plugs too (it had some odd Champion model in there, not even an equivalent to the manufacturer suggested AC Delco plugs). Turned the key tonight, started right up and ran smoothly. Yes! Time to time the engine. I verified that a mark/notch on the pulley coordinated with TDC mark on the block when piston was TDC, or at least pretty G.D. close from as best I can estimate staring at it with a light down the spark plug hole and rocking the crankshaft back and forth. I had borrowed a mid 80's era sears and roebuck powered timing light from a friend and found the engine ran smoothest at idle ~16 deg BTDC (estimating because it's off the block marks). Adjusting it to 8 deg BTDC (manufacturer spec) made it run far less smooth and bogged the idle speed right down. Should I borrow a different/newer timing light? The one I borrowed has no advance timing settings so I'm pretty sure I wasn't doing it wrong. I don't feel comfortable running it at the 8 BTDC setting for any length of time