Mercruiser 4.3 EFI Fuel Pressure Regulator

[Connermcd4516]

I have a 1999 Bayliner Trophy cuddy cabin walk around with a 4.3L EFI I/O. I have been having issues with the boat getting starved for fuel when under load. When the boat is in the driveway and running off the garden hose, everything sounds perfect whether it is in gear or not all the way up to 5-6k rpms. Yet when it is in the water and put under load, the boat will throttle down significantly on its own and occasionally backfire. It is definitely a fuel issue. My mechanic and I looked at it and tired all the simple solutions, new gas, fuel filters, tune up, etc., but nothing has done it. After researching for awhile I found some people who had the exact same symptoms as my boat, and it turned out to be the fuel pressure regulator. I am thinking that's what is wrong with my boat too. After looking at it with my mechanic, he thinks we need to pull the engine to access and replace pressure regulator. It is in a pretty bad spot underneath the port side motor mount.

My question is 2-fold. First, has anyone ever replaced the fuel pressure regulator on this motor? If so, was there a way to do so without having to pull the engine? Second, are there any other suggestions that would cause my boat to behave this way? Any input would be greatly appreciated!

 

[alldodge]

all the way up to 5-6k rpms.

Going to damage the impeller doing that on a hose

Yet when it is in the water and put under load, the boat will throttle down significantly on its own and occasionally backfire.

Back firing means out of time or a valve is damaged, hanging or other

My mechanic and I looked at it and tired all the simple solutions, new gas, fuel filters, tune up, etc., but nothing has done it.

Must be a mechanic in name only. Its pretty simple to measure the fuel pressure to see if the pump or regulator s the issue.

Whats your serial number?