GT 40 Reduced Power

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   Hello,
Last summer our GT-40 stopped producing top end power at WOT. Initially the motor would max out at 4200 and then surge to 4800 which is normal WOT RPM for us. As the summer went on the surging stopped and it just topped out at 4200. In the process a cracked spark plug and a bad fuel relay were replaced but I suspect these were independent problems and the problem persists.
      A fuel pressure check showed 38-40 PSI at WOT. The plugs, wires, cap, and rotor have been replaced. The fuel filter has also been replaced and the fuel line section inside the FCC to the high pressure fuel pump appears to be in good condition. A diagnostic scan did not produce any error codes. Using a stethoscope the fuel injectors all sound as if they are operating normally. 

It may be time to get a professional involved, but I am grateful for any suggestions or guidance in the meantime. 
Thanks,
Jackson

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minasianj Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: September-03-2008 Location: United States Status: Offline Points: 12	Post Options Post Reply Quote minasianj Report Post Thanks(0) Quote Reply Topic: GT 40 Reduced Power Posted: May-08-2013 at 11:59pm
	Hello, Last summer our GT-40 stopped producing top end power at WOT. Initially the motor would max out at 4200 and then surge to 4800 which is normal WOT RPM for us. As the summer went on the surging stopped and it just topped out at 4200. In the process a cracked spark plug and a bad fuel relay were replaced but I suspect these were independent problems and the problem persists. A fuel pressure check showed 38-40 PSI at WOT. The plugs, wires, cap, and rotor have been replaced. The fuel filter has also been replaced and the fuel line section inside the FCC to the high pressure fuel pump appears to be in good condition. A diagnostic scan did not produce any error codes. Using a stethoscope the fuel injectors all sound as if they are operating normally. It may be time to get a professional involved, but I am grateful for any suggestions or guidance in the meantime. Thanks, Jackson

Bri892001 Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947	Post Options Post Reply Quote Bri892001 Report Post Thanks(0) Quote Reply Posted: May-09-2013 at 4:43pm
	Does it run smoothly at the new lower RPMS? Does the boat have Perfect Pass?

minasianj Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: September-03-2008 Location: United States Status: Offline Points: 12	Post Options Post Reply Quote minasianj Report Post Thanks(0) Quote Reply Posted: May-12-2013 at 1:37am
	The boat runs smoothly at all RPM's and does not have perfect pass.

Bri892001 Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947	Post Options Post Reply Quote Bri892001 Report Post Thanks(0) Quote Reply Posted: May-12-2013 at 11:57am
	My theory with the Perfect Pass was maybe the throttle wasn't getting opened all the way. Hmmm... This exact problem came up once before. I can't remember what the solution was or if it was posted. I'll try and look when I get back to a computer.

Bri892001 Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947	Post Options Post Reply Quote Bri892001 Report Post Thanks(0) Quote Reply Posted: May-14-2013 at 4:05pm
	I feel if it was a fuel delivery or ignition problem, you'd see some surging or hesitation. A good question for someone out there real familiar with these: What would happen if the Spout connector was dis-connected, or if the ignition advance mechanism/program was otherwise disabled? Would it cause this condition?

GT 40 Reduced Power

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