Back Fire through intake
 

Ran my boat 1st time this year a couple weeks ago . Ran fine when I put it away last year .. I go to hammer down an my starboard engine is bogging down an finally kicks in an I take off then I hear a popping noise an alarms going off .. take off again same thing ..every couple minutes er so pop . Take it to local shop explain symptoms . They replaced plugs an caps say good to go .. went back out yesterday.. same issue. I also noticed tachs are setting at around 1500 when I shut off the keys turn keys on they drop to 0.. 502s MPIs 2000 vyper.. any help would be great .

I'm guessing a fuel issue from sitting, have you checked your fuel pressure?

Take it back to the shop. Make him make good .

No I haven't checked pressure yet.. just happened put it in yesterday... I am going to contact the shop tomorrow.. ud think they would of figured it out instead of just throwing parts at it ... its just course driving me crazy .not very much time to boat in northern Michigan.. keep thinking it may be electrical seeing the tachs are acting up at the same time. An alarms going off ... thanks for input

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Actually a boat in this case …