Mercruiser 7.4 mpi fuel rail question

[Chased1]

Hello every1, im getting ready to to upgrade the fuel system on my 7.4 mpi. Does anyone on here know whats the type and size of fitting on the fuel rail where the braided line screws into the fuel rail?

 

[alldodge]

The fuel rail lines do not have fittings such as those that screw into the rail, they are holes and the lines have O rings to seal. There are keepers that keep the lines from pulling out. The link below is for VST (don't know your serial number) but the lines are similar/same with cool fuel.

They can be drilled and taped for AN fittings

https://www.mercruiserparts.com/bam/subassembly/31810/2336/10

 

[Scott Danforth]

Hello every1, im getting ready to to upgrade the fuel system on my 7.4 mpi.

Why?

the stock fuel system will flow enough fuel for over 700 hp. the base engine architecture, the injectors, etc. will limit you way before your fuel rails, etc.

 

[Chased1]

The problem is that i cant get to any of the stock componants without pulling the engine out. The cool fuel system is conveniantly placed behind the motor mount and i cant even get to the cover. The boat is being used in colder climates so there no need for the cool fuel.Not being able to test and diagnose the componants because of accessabilty is ridiculas to me. Im pretty sure i can design e better system than that i just need to find out what kind of fitting is on the fuel rail, i m going to attack it today to find out.

 

[Bt Doctur]

the cool fuel unit is your high pressure pump, and that pic does not show a fuel injection rail connection

 

[scoflaw]

That pump drops down when you take the 2 nuts off the bracket, you don't take the cover off
Undo the 2 fuel lines at the filter, drop it down and slide it back a bit, so you can take out the single screw that holds the rail fuel line on, and out it comes. Not a big deal at all unless your working on the stbd. engine on a twin setup

 

[alldodge]

Many have gotten rid of the pump and many just reroute the return line like mine was done during firepower. If your going to change the fittings then remove the rail, cut the end where current fittings are, then retap for AN . The return goes back to the tank and the supply from pump.

 

[Chased1]

Thanks for the replies guys, very helpful