2003 GTX DI "cranks but it won't stay crunk" "turns over and fires but won't run"

[Mini Trail]

I honestly hate that this is my first post but I didn't have much to add until now. I intended to buy a fairly modern boat to take on a vacation trip in two weeks. I just brought home a 2003 GTX DI that looks brand new and was apparently running two years ago but has not been started in a while. I filled it up, brought it home and boosted the battery to get it to turn over.

After hitting the button a few times it began to fire but would run for a fraction of a second and quit. If it was a car I would assume a fuel pump. I read everything I could find on the model today, purchased a battery, installed it and it exhibits the exact same issue.

• Battery is at least decent, still charging but brand new and perfectly capable of turning over the engine.
• Fuel pump is producing a lot of pressure. I don't have a gauge that goes high enough but I pulled the input at the fuel rail and the pump makes more pressure than I can hold back with a thumb.
• Ignition is good. I turned out the lights and the spark from the plugs is blinding. I also tried new plugs. I also noted that the new plugs were a little wet when I pulled them.
• The fuses at the MPEM were all good (are there more fuses?)

I read every thread about these models I could find on every forum I could find and didn't find another example of another similar DI boat exhibiting this behavior.

Again, hitting the starter button will turn the engine over, the engine fires and runs a little, dies and the starter quits. Every once and a while the starter will continue to run after the engine quits running but the engine never re-fires. If I had to guess I would say that something is telling the ignition to quit firing.

 

[Dr Honda]

Welcome...


But first.... DO NOT BOOST, JUMP START, OR TRY TO START THE SKI WITH A CHARGER HOOKED UP !!! YOU CAN FRY A VERY EXPENSIVE MPEM !!!! (the computer)



OK.... with that out of the way...


the Di skis are hard to diagnose, and unfortunately... a lot of "fuel flow" does not mean it's building any pressure. Remember... this fuel system is forcing fuel directly into the combustion chamber, and it has to overcome that pressure.

So... you need a gauge to check. (no guessing on this one)

Please check, and report back on:

1) Fuel pressure
2) Air pressure
3) compression


If the electrical system is working... 90% of the time... it's one of those issues.

 

[mtnandy]

Drain the gas and refill with high octane. Then change the spark plugs and give it a try

 

[Coastiejoe]

I just want to reiterate what Dr. Honda said.

The DI machines are NO FUN to figure out and the fuel pressure is crucial. If memory serves me correct I believe I read it is near 107 PSI.

You MUST get an accurate reading of the fuel pressure and compression. If you are getting spark, then it must be fuel or compression issues, (assuming there is not a timing issue and the internal components of the engine are all good).

 

[Mini Trail]

Welcome...


But first.... DO NOT BOOST, JUMP START, OR TRY TO START THE SKI WITH A CHARGER HOOKED UP !!! YOU CAN FRY A VERY EXPENSIVE MPEM !!!! (the computer)



OK.... with that out of the way...


the Di skis are hard to diagnose, and unfortunately... a lot of "fuel flow" does not mean it's building any pressure. Remember... this fuel system is forcing fuel directly into the combustion chamber, and it has to overcome that pressure.

So... you need a gauge to check. (no guessing on this one)

Please check, and report back on:

1) Fuel pressure
2) Air pressure
3) compression


If the electrical system is working... 90% of the time... it's one of those issues.

I very much appreciate your reply. Your dedication to providing answers on this site is evident and greatly appreciated.

I read a lot of threads after I tried to start it and was up all night scared to death that I had fried the electrics trying to jump it. Yesterday Morning I was making a video to show the problem and in the process I managed to get it to run on one cylinder for a couple of seconds. I read the manuals and learned how to flood the cylinders with oil so I soaked them and started it with the trottle open. Eventually I got it to run again, then the other cylinder kicked in. It was rough and smokey but running. When I cut the throttle it shut off. I let it sit for a while and got it running again for a few seconds and this time it tried to idle (but couldn't). I felt a lot better and we went ahead with our trip. I started it again on the trailer and even got it to idle so I knew it was clearing out. It was really smoking up the campground so I quit messing with it.

Apparently the boat had been sitting longer than I knew or wasn't as well prepared as I was led to believe. I got it in the lake later in the day and ran it on the trailer in the ramp. It had a hard time running while the pump was working but got better and better. Eventually we launched it and rode around doing 5-10-15 miles per hour until we finally got it cleared out in all ranges and after an hour and a half got it up to a high of 54. It also idles reliably and can take sudden throttle and chopped throttle and has no misses at speed. I am now confident about the boat's reliability.

I do still have a question though. Would it be ok to run some Berrymans B-12 or Yamalube ring-free through the system to cleanse the injection system?

 

[Coastiejoe]

Generally speaking, no cleaner of any kind should be used on a 2-stroke engine as it washes away the lubrication.

There may be a cleaner that has lube as part of the mixture specifically for 2-strokes. If so, that would be the only cleaner type that could be used.