an FYI as many think these are the fuel pressure regulators on the fuel rails - its not - it is a fuel pressure damper - page 4 of the link - I understand this is a 496 in the link but wanted to show what I am talking about. Some people call these GM dummy regulators. This is a GM installed damper and the marine OEM's do not change them.

If the app has a GEN II or Gen III cool fuel all the fuel pressure regulators are in the cool fuel. Gen II cool fuel it is mounted on the top of the cool fuel.

http://ww2.justanswer.com/uploads/ke...5804_EN_09.pdf

Mine was doing the exact same you just described with the vst. Poor performance after 3k rpm and eventually just didn't get up on plane at all. Popping and spitting like a whore on a Friday night. Can the system if you can it's garbage. I Finally ripped it all off and just did a straight electric a1000 to the rail. The thread is in the diy section right now.

My bad I thought I had these links in post 10 showing for the earlier 1996 502 MPI fuel pressure regulator and then listed the gen II cool fuel. Have no idea why my links did not post and just realized it.

early 1996 502 MPI - VST link with fuel pressure reg. - number 15 in the diagram.

http://images.jamestowndistributors....MMON/38607.png


later 1996 502 MPI cool fuel II fuel pressure regulator number 13 in diagram.

http://www.marineengine.com/parts/me...MMON/38612.gif

Thanks for the update BUP. I didn't know they had the cool fuel in 96, I thought they started in 97, but as you say, what is the serial number. That is what tells the tale.

I just knocked the hose off the fuel pressure regulator this weekend. I was mopping some water out of the bilge (boat is on a lift and water was too cold to just pull the drain plug) and I guess I caught the hose. I'm looking at these diagram links BUP posted and it looks like I will have to get the cool fuel cover off to reconnect...I've dicked with that assembly before and it wasn't fun in my app. The regulator does sit well behind the cover, right?

Hey guys sorry I haven't come up with a serial number yet, like I said before the boat is at a marina for repairs, it is definitely a 96 with the vst system not cool fuel system. My friend said they recieved a new regulator today and will install tomorrow. I'll follow up with results, like I said before, I'm not so certain of the marinas capabilities. I've already suggested that after this he might want to bring elsewhere to a more competent shop.

Was the vacuum line to regulator in good condition and attached well at both ends ?

.I will know more and ask that very question this afternoon

Update: we brought the boat for a second opinion. They took compression on the cylinders and it looks like 2 are measuring in at 50psi, not good. They didn't perform a wet compression test or leak down so we don't know if it could be valves, rings or at what extent the damage may be. To speed things up, my friend and I thought about buying a nice used 502 mpi, or even 496 ho. Could this be a viable option? Considering it maybe at least another month to have his rebuilt depending what is wrong and now that we are getting into summer. What do you guys think?

I would look into buying another motor if you want to get back on the water this summer. Having a marine motor rebuilt properly in a timely manner seems to be difficult to do.