1998 200Hp Mercury EFI Fuel Pump issue

[Brad Fideldy]

Bought a boat recently 2004 20' Procraft with 1998 200EFI. Boat lacked power on take off and then felt like it ran out of gas and quit. Fuel pressure is zero, so basically bad fuel pump

Issue is though the guy I bought the boat from said that the fuel pump was rewired to a keyed terminal because some high limit module went out. So now basically when you turn the key to on the fuel pump has 12 volts constantly. He said his mechanic told him this was common instead of replacing the $500 module.

Question is......did this rewiring cause my fuel pump to fail? the wiring was changed 8 months ago. I don't know that the fuel pump should have 12 volts to it all the time or if it should modulate to lower voltages depending on the demand from the motor. Some cars run on 12 volt all the time, but they also have a fuel bypass line. Seems like running the pump to max output may be why it failed to begin with.

I don't want to replace and have to put in another pump in a few months.

 

[Dukedog]

ta start, that is tha way around a bad "fuel pump driver circuit" in tha ECU. $500 bucks won't cover it... key switch run?.. yes it is very common.. most use a relay of sorts but its not required ta do so.. it will not cause tha pump ta go bad.. know of many that's been that way a very, very long time.. there will be some that will say do not do this for whatever reason.. some, like myself have done it since tha "pump" was tha issue when it came on tha scene many years ago.. without any problems.. its NOT like a car at all... JAN... all high performance mercs COME with a constant 12v ELECTRIC fuel pump that is key operated.. all regulated at a max pressure.. only tha efi has a return but it is used ta maintain MAX pressure which it stays at at all rpm, not to turn pump on and off or regulate pressure at different rpm...​

when tha boat stalls/shuts down is tha pump still runnin' but not makin' pressure?.. if so then you might look at mechanical pump instead and/or fuel delivery to it and to VST.. ie: bulb, fuel lines, filter etc..check tha VST for fuel by pullin' ​

tha drain plug in tha VST ta verify its holdin' fuel..

if boat shuts down and pump "quits" runnin' and still has 12v across tha terminals then tha electric pump is bad...​

 

[Brad Fideldy]

Ok I just don’t want to be replacing a $766 pump regularly. And when boat shuts down the pump is off. Could hear it run before when just key is on but now nothing. There is 12 volts to the pump when key is on

 

[Dukedog]

ya might wanna add a relay ta power tha pump.. power tha relay with tha switched power.. can use a larger gauge wire for pump power.. might help and certainly can't hurt...