Fuel Pressure Fine.... still replace pump?

[lay-a-wake]

The problem im dealing with is a lack of power. The engine (5.7 L marine power, 178 hrs) sounds fine, but is slow from the hole shot and only goes about 30 mph at WOT. It seemed like a fuel issue to me, but i checked the fuel pressure on the lake under a load. Pressure at idle is about 52 psi, and increases with more throttle. At WOT it got up to about 58 psi. I have read other posts where people replaced there high pressure fuel pump under the same condionts and said it fixed the power problem. So if the pressure is good, the pump can still be bad??

[Stingreye]

Old gas or water in the fuel? Were you surfing with the port side fuel vent was very close to the water. I had similar symptoms. Adding sea foam masked the true problem that I suspected was WATER getting in my vent when going heavy on the regular side. I also fouled my plugs after going through some stale gas.

[lay-a-wake]

I wondered about bad gas so i actually siphoned the gas out, replaced the fuel filter, and put new gas with seafoam treatment back in the boat. What your saying makes perfect since about water getting in that vent, is there nothing to stop that from happening, becuase yes we do surf on that side.

[Stingreye]

I moved mine forward above the rub rail near the front cleat. VERY EASY DIY. Remove old, get longer hose, drill new hole, chamfor (sp?) put in new one. Plug old hole, I put a bilge discharge there.

Did you have these problems after changing out fuel but before surfing that side?

If it ran well, then I would look at moving the fuel vent and get a thru hull and add a second bilge pump and have it discharge at the old vent location.

I also got rid of that POS Atwood surge valve on the vent line and got a Racor LG 100 fuel air separator. If your boat spews gas when filled, see if you have the atwood one. Its been worth it since I swapped out that for the Racor. Don't get the LG50 get the LG100 that works for both gas and diesel. These devices do nothing to prevent water from entering tank. It was just something I changed around the same time. So if you have trouble filling up your tank, I would look into this.

Here is where I bought mine:
http://www.defender.com/product3.jsp...9060&id=133911

Here is the writeup you can see the atwood pictured one:
http://www.boatus.org/findings/40/default.asp

[lay-a-wake]

I also got rid of that POS Atwood surge valve on the vent line and got a Racor LG 100 fuel air separator. If your boat spews gas when filled, see if you have the atwood one. Its been worth it since I swapped out that for the Racor. Don't get the LG50 get the LG100 that works for both gas and diesel. These devices do nothing to prevent water from entering tank. It was just something I changed around the same time. So if you have trouble filling up your tank, I would look into this.

I havent had any issues filling the tank up and fuel coming out of the vent, but i have read about that issue. The last time the boat ran right, was Memorial weekend. We had it on the water for two days and it ran great the whole time. We did surf on the port side where the fuel vent is....but the boat ran fine after surfing all the way up until we loaded it on the trailer. it wasnt until the next time out (2 weeks later) that it started having problems. If water would have gotten in through the fuel vent, wouldnt we have noticed it that day?

[Stingreye]

That sounds similar to my issues which is why in the past I have said that I was "suspecting" getting water in the fuel. I can without a doubt say the problem went away when I moved the vent and replaced the check/surge valve.

Here are the two trips I ran into and remember, one happened the next day, the other later.

1) We were camping and my wife and I both surf goofy and had no regular people out with us. No problems for 3-4 days.
2) Day 4 evening, we surfer port side for about 1-2 hours and didn't seem to have any problems.
3) Day 5 loaded up on the goofy side and lost power. Could not get to 11MPH loaded.


Another time same day
1) Surfed Goofy first for about an hour
2) Surfer port for about an hour and then while I had a surfer up. The boat lost power from 11 MPH down to 9MPH. We were weighed down heavier this trip and may have caused increase water to get into the vent.
3) I opened the gas cap and we got some of the power back. It made me think it might be a faulty surge valve where it wasn't letting the tank breathe. But we didnt get all the power back so I am leaning towards water looking back now.

At that point, I read about other people moving the fuel vent. Seemed like a good idea so I moved it, you can actually just connect your long fuel vent hose right to the check valve, you don't even need to get all the way to the tank. That's also when I ran across the boatus article for surge valves. So I decided to try the Racor one.

Since making those two changes, I have had zero power issues. I am leaning toward thinking it was a water issue Vs the check valve. I had problems before those two trips but I thought then it was bad gas then (because replacing gas fixed problem). I am thinking I may never have had bad gas.

You could still be having either fuel pump or injector issues but it just sounded similar to my issues and it was a relatively cheap fix (I did the whole fuel pressure water test under load too because I was assuming the same you were that it could be the pump).

Good luck and report back if you solve the problem!

[little_criket]

The problem im dealing with is a lack of power. The engine (5.7 L marine power, 178 hrs) sounds fine, but is slow from the hole shot and only goes about 30 mph at WOT. It seemed like a fuel issue to me, but i checked the fuel pressure on the lake under a load. Pressure at idle is about 52 psi, and increases with more throttle. At WOT it got up to about 58 psi. I have read other posts where people replaced there high pressure fuel pump under the same condionts and said it fixed the power problem. So if the pressure is good, the pump can still be bad??

Did you ever find the fix??? I'm having a similar issue....