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View Full Version : Stalling LT-1 Engine...I'm stumped!


megapea
07-25-2013, 11:45 PM
Boat is a 99 MariStar with the LT-1. During the last 2 weekends, I've ran thru about 70 gallons of fuel (skiing, wakeboarding, tubing, and just cruising) During all that time, the engine stalled about 5 times. It always stalled at idle, or the transitition from idle to just starting to give it gas on pulling a skier. She always refires instantly upon turning the key. It seems to have always happened when it was warm (temp is always 159 - 160 degrees on the gauge) The boat did this 2 or 3 times last year, so before I took it out this year, I changed the fuel filter and original fuel pump (ie..fuel pump 101 thread). I also replaced the battery this spring too ( I installed a dual battery setup last year ie...official dual battery thread). I run Royal Purple 15W40 synthetic oil in her since 2009. Even at 23 feet and with 60 gallons of fuel, she runs like a scalded dog at any range of the throttle, and will reach 50 MPH on the speedometer with several people in the boat. On cold start, she fires perfectly, and goes into a higher idle for a few seconds and then levels off. It has never stalled when cold. I assumed that it could be the gas, so I bought enough fuel injection cleaner for 2 tankfuls, but that didn't seem to help. This is a very intermittent problem and I am stumped! Any engine gurus out there have any suggestions? Like I said, 99% of the time, the boat runs perfectly. It is just the low idle speed that makes it hiccup every once in a while. Any and all feedback is welcome!!! Thanks!

1redTA
07-25-2013, 11:47 PM
Throttle position sensor?

megapea
07-26-2013, 11:38 AM
Is there a way that I can test this? I've done a little research on this and it does sound like it may be a possibility. What can I do to see if it's bad.

Ski-me
07-26-2013, 12:29 PM
I think you can test it with an OHM meter or Voltage meter somehow.... Like 0 - 5.

megapea
07-28-2013, 03:02 PM
You Tube had some videos on testing the TPS with a multi meter. I will try that this week and report back on the results I find. Anything else anyone can think of that could be causing this?