Johnson 28HP SPL Cutting out?

[LotusEarth]

Hey Guys!

I have a fantastic engine from 1989 called the Johnson 28HP SPL on a 14 foot Starcraft Seafarer DLX aluminum boat.

Today the engine was running strong when all of a sudden it cut out. There were no signs of running out of fuel or missing, just an abrupt cut out.

She fired right up and I continued on until I was coming off the throttle and she immediately cut out again.

This time she wouldn't fire back up. I tried a half dozen times and then let her sit and then tried again and she simply wouldn't start.

I got towed a long way back to the closest dock and again she fired right up.

We decided to try and make it up the river to the dock where we had the trailer and she did just fine, only cutting out at the dock when I throttled her all the way down.

The fuel tank looks pretty new and was full when I bought the boat along with a bunch of other recent obvious repairs.

I don't know how old the fuel is in the tank, but the guy who did the work said he flushed out the fuel line when he did the carb.

Wondering if it would be beneficial to buy a brand new tank and line to rule out any contaminated fuel issue or debris in the line.

Also feel like it could be some short in the electrical?

Wondering where you would start to try and figure out this problem?

Thanks so much!

Tom in Florida

[boats.net]

If this is a portable gas tank make sure it is venting, check the vent screw is open on gas cap. When it shut off did you try pumping fuel primer bulb, was it sucked flat, were you able to pump bulb up firm? Did you try using the choke to get running?
Check for water in fuel, look for pinched fuel lines, look for fuel leaks.

[LotusEarth]

Thanks for the reply!

The tank is Atwood and appears to have a built in vent with no screw in the cap. The pump bulb was firm and the line is new (looking) with no kinks and flexible. Would a fuel problem cause such an abrupt cut-off or would it sound like an engine running out of fuel i.e.: racing a little, sputtering and then dying.

The first time it cut out we were full throttle and it just instantly died. The second time I was throttling back and it died just after I moved her a slight bit from full throttle.

She had ran like new for 40 minutes or so at full throttle crossing a large channel and the engine still felt very cool. When starter her after getting towed back, again she ran like new for another 15-20 minutes back to the dock.

Trying to figure out if it is more likely a fuel issue or electrical?

Thanks so much,

Tom

[boats.net]

If that gas tank is not venting then it will normally run 15-20 minutes and shut off, runs out of gas. Might try loosening or removing gas cap to see if it is a venting problem. Might check for spark at plugs when it shuts off to see if loosing fire to cylinders.