Top End Speed

[Thomv]

I just had my dealer add two high pressure electric fuel pumps before the regular water cooled fuel pumps on my 29 foot Powerquest. The new fuel pumps finally took care of my no starting condition after running both motors for an hour or two and then shutting them off, sitting for about 3 hours on the beach and then having both motors turn over but never fire up until I opened the hatch and had them sit for another two hours. Very nerve racking to say the least. Was told by my dealer that both motors were going into vapor lock from the Florida heat. Glad that problem has been fixed. My question concerns my top end speed. before having this done my boat topped out at around 70 MPH on my GPS. Now it is only running at 53 MPH GPS at only 4,000 RPM. What do I need to do to get the RPM up higher but not past it's redline RPM. Also, both motors now are no synchronized with the throttle levers. One is idling higher then the other.

 

[tpenfield]

This might be a question for the shop that did the fuel pumps. "He who touched it last" theory comes to mind.

 

[Fun Times]

I just had my dealer add two high pressure electric fuel pumps before the regular water cooled fuel pumps.

So to try and help alleviate EFI vapor lock, one trick is to add low pressure booster fuel pumps inline before the fuel filter/s to basically help pressurize the high pressure fuel pumps mounted down by the port side oil pan behind the motor mount.

If you added high pressure fuel pumps inline and are also using the stock high pressure fuel pumps, than you are over fueling the engine which could cause a loss of performance like you're noticing including the variance idle RPM.

Do you have any part numbers they installed?

 

[alldodge]

IMO there is a much better way to stop vapor lock then using additional pumps, but it's just my opinion. Agree with FT, I think your over fuelling now and this is way you cannot reach previous rpm's and speed. The real bad side is your motor is probably running like a pig and washing the cylinders a bit. If this continues you will be rebuilding your motors due to the excess fuel

 

[Thomv]

So to try and help alleviate EFI vapor lock, one trick is to add low pressure booster fuel pumps inline before the fuel filter/s to basically help pressurize the high pressure fuel pumps mounted down by the port side oil pan behind the motor mount.

If you added high pressure fuel pumps inline and are also using the stock high pressure fuel pumps, than you are over fueling the engine which could cause a loss of performance like you're noticing including the variance idle RPM.

Do you have any part numbers they installed?

My bad. They are low pressure inline fuel pumps. I am not sure of the part numbers because my Son, who picked up the boat from the dealer, still has the invoice in his truck. H is supposed to drop it off later this week.