jetboat engine dying

[melissa ANN villegas]

I have a 1999 exciter twin inboard engine jetboat. One engine will start, then die and 1 or 2 minutes. The battery is fine. The starter was changed. Does anyone else have any suggestions? Also, is it normal for both to smoke alot when started? Thank you!

 

[swatski]

@melissa ANN villegas I would try to contact @4x15mph, his threads on rebuilds are awesome:
https://jetboaters.net/threads/carburetor-rebuild.3793/
https://jetboaters.net/threads/cleaning-out-the-cooling-system.3671/#post-63915
https://jetboaters.net/threads/stalls-when-i-give-it-gas.10747/#post-183725
https://jetboaters.net/threads/top-end-rebuild.19906/

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[4x15mph]

Are you sure the engine isn't just dying due to one of the rear clean out plug hatch, safety switches being out of alignment or in need of replacement? You can test this by holding it down (if you are out of water) or tape a quarter to the underside of the hatch so it presses down on the switch. Understand?

Otherwise, dying in 1 to 2 minutes sounds like a fuel issue but so hard to diagnose. is the fuel turned on from the fuel tank for both engines? I ask since I made that mistake once....

Is the boat new to you? Carbs are something you want to have cleaned up and while I did it myself a couple of times, I recently chose to send them out professionally. I'll let you know how that compares when I run it this next season.

Yes, they definitely smoke especially when first starting them. They also smoke more at idle. Are you mixing oil/gas or do you still have the oil injection system? If you mix, you probably will have more smoke since it is not a variable rate of oil per gas controlled by your engine throttle

Congrats on the boat. People love those exciters but search around since there are some preventative things to do for those particular boats (mufflers rub away fiberglass, power valves, .... )

 

[the MfM]

Yes the smoke is normal and a good sign. Unless of course it’s too much ... the oil injection lines have check valves that sometimes fail.

Doesn’t sound like an electrical issue. But with these boats it’s easy to rule out an safety switch problems by swapping the wire harness for the port and starboard engines. Under/behind the helm are two large quick connect plugs. One for each engine. Swap them and see if the problem follows.

Check compression

Check the fuel lines to see if they are soft and gummy feeling. And the fuel filters... consider adding a water separating canister style while your at it.

Check spark and put in new spark plugs... make sure there isn’t a mouse nest or something top of the flame arrestor.



I think the exciter engines have an external fuel pump which would be my next guess.