2004 Sunsport V Fuel Issues

[jsmilez]

Hey Guys,

I have been searching the forums to find a solution to what might be going on with my boat, but have found nothing. So 1st of all there was a new block put in the boat 2 years ago. It ran pretty well last year, but this year I am having some issues. When i first start it up it sounds and runs amazing then I will run it for 30-45 minutes and it seems to then it starts to whine a little & idle weird, backfire, and even die. Sometimes it will run ok for a few minutes, but then it goes back to a weird idle, back fire etc. I put a new fuel filter on it today but still had the same issues. I thought it might be fuel so I have been filing it up every time and today when it started acting like this i had 5 gallons on the dock and put it in there and it didn't really seem to help. I also put the fuel pressure gauge on and when it was running great it was consistant at 30 psi. then when it started acting weird it would go all the way down under 10-15 psi. So it seems like a fuel pressure issue or not enough fuel getting to motor. What do i need to do to fix this problem a new high pressure fuel pump? (if so what part # there are tons of options when searching on the google) Low pressure fuel pump? sensor? Thanks in advance. I got great deal on the boat and this is my 3rd Supra 93' Comp, 99' launch, then went to an Axis and the wake just wasn't the same so now I'm back with a v-drive sunsport! Love my supra's just got to get this fixed!

[h2o-ski]

I agree with your assessment, however one thing I would suggest looking for is whether or not you are getting vapor lock. If it always runs fine when cold then that could be your culprit. Does your engine have a low pressure fuel pump?

[jsmilez]

I agree with your assessment, however one thing I would suggest looking for is whether or not you are getting vapor lock. If it always runs fine when cold then that could be your culprit. Does your engine have a low pressure fuel pump?

Yes it has low pressure and high pressure.

[jsmilez]

Yes it has low pressure and high pressure.

I am took a part the floor and looked at gas tank and lines to see if there were any cracks or issues on that side and everything looked good. I am going to try to take it out this afternoon to see if I can cool the fuel pumps with a cold towel to eliminate vapor lock.

If it is vapor lock would going to non ethanol fuel eliminate the issue??

[h2o-ski]

Normally the issue is resolved by adding the low pressure fuel pump. Not sure how to test this, but I would see if you could test the low pressure fuel pump to make sure it is working.

Going non-ethanol can help, but the formulation changed to make gas evaporate more easily rather than before where it was formulated to stay in solution.