95 SN surging

[scooter t]

Hey Guys,
I am in need of some guidance. I have received some advice on CC Fan, but because of my lack of mechanical experience, I am still searching for the most practical advice before I move forward in my repair. I purchased my boat last year. It is a 95 SN Signature Edition. It only had 311 hours when I got it, and it now has 351. Boat cosmetically is in pristine shape. The PO told me that the boat was surging while in gear, but it was not bad. He mentioned it may be the perfect pass messing with it. The boat ran pretty good last year BUT it has consistently gotten worse. I have good hole shot power, it always cranks first turn of the key, and the surging is not as noticeable at WOT, which right now is only 38 mph. It seems most predominant at 15-20 mph.

This is what I've checked: Anti siphon valve appeared functional; screen of the fuel line dip tube was clean;
I disconnected the feed into the LP pump and eyeballed the screen, it looked ok; I replaced the in line fuel filter; and I tested the fuel pressure on the schrader valve: key in the on position 40, boat cranked in neutral 33, boat in gear up to 1500 rpm still 33.

Money is tight, and the closest certified mechanic is at White Lake in NC.... I'm in SC. I am mechanically challenged, yet a fast learner.... any suggestions would be greatly appreciated.

[scooter t]

I spoke to one guy on the phone at a marina and he said "because I only have 33 psi at the shrader valve that my problem is definitely my HPFP." He did mention that you can disconnect the vacuum hose from the FPR to verify..... but he wasn't real clear on what would happen when the hose is disconnected. Will the fuel pressure go up?

This is an SOS, my family is desperate to ski.

[Chexi]

Talk to the mechanics at White Lake. 33 psi does not sound far off to me.

Your timing could be off, which I believe can cause surging. Have you perused the PCM manuals on this site? BTW, do you have a GT40?

[scooter t]

I do have the GT- 40. I haven't checked out the links on the site, but I have googled it and read several forums. Some of the fixes were the FCC, but I don't have one.

[nms1991]

What is your fuel pressure at higher speeds does it reach 39 psi +r - 3 psi, because if it is not reaching this psi then you have a fuel delivery problem, and you should check to see if you low pressure pump is providing enough volume, but one thing you want to check is the fuel filter that is mounted to the stringer under the rear floor board and make sure it is not plugged with debris also did you pull out the fuel pickup screen and check it for debris? And yes the fuel pressure will go up as the fuel pressure regulator drops the pressure with more vacuum on the port.

[scooter t]

I checked the pressure last night with a new gauge ( at the shrader valve) and what I noticed was the first several times I turned the key to the on position the pump would pressurize but I wasn't getting the full 39 psi. I would have to key on two-three times before it reached 39. Cranked and in neutral I have 34, and up to 2000 rpm I'm still at 34. One of the guys associated with White Lake said anything below 38 is not good?? When I pulled the vacuum hose off the FPR the fuel pressure jumped up to 40 psi. So..... does that point to the FPR or a FP?

I just replaced the in-line fuel filter so I'm good there and I checked the screen on the fuel dip tube and it was clean. I spoke with a local this morning and he said to hook the fuel pressure gauge back up, bring the boat up to speed where it was surging most (15-20 mph) and then release the fuel pressure on the gauge and if the motor won't overcome, then it 's likely the HPFP. So far, everyone around here once they find out it's EFI, they tell me they can't work on it.

How do I test the fuel volume from the LPFP?

[scooter t]

Hey Guys,

Just want to update you on my situation: I tested my LPFP (low pressure fuel pump) and was getting the 16 ounces of fuel in 10 seconds that I was told I should. So I went ahead a put a new HPFP in and ran her for a skinny minute last night in the river. Instead of 38 at WOT I'm now running 45 and I didn't notice any surging. If the rain will hold off, when I get off work today me and the family are going for a ski . Thanks for your input, and I hope my fix is complete.