try bypassing the teather switch. a friend of mine had a similar problem only when is was very rough, chased it for months and thats what it ended up being.

Ok replaced cool fuel electric pump motor runs fine for about 15 min then same ****? lean pop if i idle around for a while all good again for about 15 min then again? Its driving me crazy. I switched fuel tanks so it not the pickup or tank issue?

I wish I saw this thread before. I have 575sci and had the same problem for the first part of the season, replaced everything including the electric fuel pump. Turned out to be the mechanical fuel pump. If you have a mechanical in font of the electric (later 500s had these) check that as well, I haven't had a problem since.

Hey Mike, one other thing to check is play in the distributor shaft, if it moves too far up and down it can cause the pickup to send funky signals. If the tach gets real twitchy or jerky as it is happening that is a sure sign.

No Tach issues that I noticed. I'm thinking that the main pump isn't working and the electric one can't keep up after about 15 min? if I unplug the electric pump the motor won't run? I thougt it should have stayed running at idle?

No, the mechanical can only produce 5-7 PSI whereas the electric one boosts it to 40 PSI, which you should have at all times. However, your thinking is correct, if the mechanical one is weak the electric one can keep up for a while, but may be losing it when hot. Running with a fuel pressure gauge will tell the tale.

This is exactly the problem I had, I PM'd you my phone number, gove me a call and I will talk you though it.

Holly $hit this is frustrating!!!!
Replaced both pumps have good fuel PSI but boat still doing same thing.
Runs great for 15 min or so then just looses rpm like something gets hot?
Let it idle and hammer throttle runs great then same ****.
Its driving me nutzzzzzzz

weak valve spring??it may be time..or.. one or more of your injectors are lein..you would be suprised what i have seen in some of the chit come out of them when my buddy back flush's them..

Have you scanned it to check for codes?