GT-40 Fuel Pressure

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   I posted earlier about my recently acquired 1999 Sport Nautique. The previous owner was up front about a stalling/no start issue the last time he was out. He thought it was fuel related because no fuel was coming from LPFP while on the trailer. I spent the last two weeks changing fluids and cleaning up. Today, I took the boat out for an initial test drive and brought my fuel pressure gauge. Initially, at idle and with a little bit of throttle I was only getting about ~31 - 33 psi. During hole shot the engine was wanting to die out a little almost stalling, with low fuel pressure. So, I removed the vacuum line on the fuel pressure regulator and fuel pressure shot up to 41 psi and became steady under  all throttle conditions. I ran the for over an hour like this with no problems. Does this mean I should replace the FPR or could it be my fuel pumps? Any advice would be appreciated. 

new sport

I also changed the fuel filter and cleaned the LPFP screen.

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sport1999 Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: May-10-2015 Location: Florida Status: Offline Points: 313	Post Options Post Reply Quote sport1999 Report Post Thanks(0) Quote Reply Topic: GT-40 Fuel Pressure Posted: May-22-2015 at 5:58pm
	I posted earlier about my recently acquired 1999 Sport Nautique. The previous owner was up front about a stalling/no start issue the last time he was out. He thought it was fuel related because no fuel was coming from LPFP while on the trailer. I spent the last two weeks changing fluids and cleaning up. Today, I took the boat out for an initial test drive and brought my fuel pressure gauge. Initially, at idle and with a little bit of throttle I was only getting about ~31 - 33 psi. During hole shot the engine was wanting to die out a little almost stalling, with low fuel pressure. So, I removed the vacuum line on the fuel pressure regulator and fuel pressure shot up to 41 psi and became steady under all throttle conditions. I ran the for over an hour like this with no problems. Does this mean I should replace the FPR or could it be my fuel pumps? Any advice would be appreciated. new sport I also changed the fuel filter and cleaned the LPFP screen.

lewy2001 Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: March-19-2008 Location: NSW Australia Status: Offline Points: 2234	Post Options Post Reply Quote lewy2001 Report Post Thanks(0) Quote Reply Posted: May-22-2015 at 10:09pm
	Engine idling 31 +or- 3 psi Key on engine off 39 +or-3 psi (may take a few cycles of key off/on to get there) The most common failure is the low pressure pump.
	If you're going through hell, keep going 89 Ski <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta

gun-driver Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: July-18-2008 Location: Pittsburgh, Pa Status: Offline Points: 4112	Post Options Post Reply Quote gun-driver Report Post Thanks(0) Quote Reply Posted: May-22-2015 at 11:26pm
	Sounds like a pretty safe bet that it's the FPR if when disconnected it allows the proper pressure. Lewy it could be a bad FPR allowing to much fuel to return to the reservoir I nstead of the fuel rails. What'cha think.

MrMcD Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3596	Post Options Post Reply Quote MrMcD Report Post Thanks(0) Quote Reply Posted: May-23-2015 at 8:26pm
	Many injection systems have a vacuum line on the Pressure regulator to compensate when you give it gas. At idle the engine has high vacuum and needs less fuel pressure. When you open the throttle vacuum goes to near zero and the Pressure regulator compensates by increasing your pressure. I am assuming this Marine conversion operates the same as the Automotive applications as it relates to fuel pressure. sounds like your pump is able to put out enough pressure, indicated by the improvement disconnecting the vacuum line so it should be OK and replacing the Fuel Pressure regulator may fix your issue. Did you plug the line when you removed it?

sport1999 Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: May-10-2015 Location: Florida Status: Offline Points: 313	Post Options Post Reply Quote sport1999 Report Post Thanks(0) Quote Reply Posted: May-23-2015 at 10:37pm
	I did not cover the vacuum outlet on the FPR and no gas was present. I guess I should have just to be safe. $160 for an oem, anyone have a part number for automotive? I was looking over the poor mans gt40 sheet and didn't see any resolutions specifically for the regulator. Is it uncommon for this part to fail? Most of the threads I've read with similar symptoms are the LPFP. The low pressure pump definitely works as I can hear gas return to the tank. Maybe I should replace both.

GT-40 Fuel Pressure

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