Esal

iTrader: (2)

I have a pair of 454 mpi Mags and one of them seems to hit a wall at about 4200 rpm. I have more throttle left but when I give it to it nothing happens. The other motor runs out to 4800 just fine. I checked the throttle body and it's opening up all the way. Any suggestions on what to look at? Thanks Eric

ThisIsLivin

You could be running out of fuel check you pressure on both motors.

mike tkach

iTrader: (3)

are both of your tach,s working properly,is the boat slower than normal,i have seen tach,s go bad for no appearant reason.

cubicinches

What year? If it's mid 90's ('93 to '96 or '97) with the VST tank mounted at the back of the intake manifold, near the distributor, check the screen on the bottom of the high pressure pump inside the tank for crud build-up. Fairly common issue with that system.

Esal

iTrader: (2)

Should I check the fuel pressure at wot or is idle ok?

Ebay Ed

if you have a rubber line on the return for the fuel take a pair of needle nose vice grips and slowly pinch off the return to increase fuel pressure my regulator went bad and it wouldnt let my boat plane for crap

Esal

iTrader: (2)

I replace the regulators on both motors last year. By the way I had the same problem last year it isn't something that developed over the winter.

Ebay Ed

it definately sounds like a fuel issue

Esal

iTrader: (2)

Fuel pressure checks out ok at idle. Also these engines are the or the surpentine belt style without the vst tank.

Ebay Ed

can you get ahold of a scanner to check things like timing advance and such you have the cool fuel system then