94 Sport fuel?

DougsdevilCC wrote: Baffled. 94 Sport 351. 490 hours. Hesitated around 2300 rpm and would not speed up anymore. Replaced fuel filter with a whole new mount and filter. Rebuilt Holly 4 barrel, wasn’t dirty. Replaced fuel filter again. Starts and runs good for the first few minutes and then hesitates again. Could it be something other than fuel issues?

Of course it could

Since 94 was one of the "ProTec" years, it would be good to know if you have the ProTec ignition system with 4 coil packs on the back of the engine and a funny looking sensor up front where the distributor normally goes...............or if it has a distributor up front in the normal spot.

Sounds like limp mode. Better check your knock sensor, and oil/temp switches. Unplug one at a time to determine the offender.

Siphon valve is clean with good push back

Pick up tube screen was clean

DougsdevilCC wrote: Baffled. 94 Sport 351. 490 hours. Hesitated around 2300 rpm and would not speed up anymore. Replaced fuel filter with a whole new mount and filter. Rebuilt Holly 4 barrel, wasn’t dirty. Replaced fuel filter again. Starts and runs good for the first few minutes and then hesitates again. Could it be something other than fuel issues?

I think a better description of what happens is needed here.

Is it a steady misfire that goes away when you reduce speed and then it runs normal till you hit your 2300 rpm again?

Like Mpost said, if it's going into "Limp Mode" the Red light should come on, since your Red light functions on startup.

Does it stall like it's running out of gas?

If I wanted to see if it was going into Limp Mode.I'd look at the diagram below and then disconnect the wire from the low oil pressure switch ( not the sending unit) and also the wire from the hi water temperature switch ( not the sending unit) , tape the ends so they can't ground against the engine block which would put you into Limp Mode and take the boat for a ride. Do the same with the knock sensor.

If it still does the same thing, your sensors aren't putting it in Limp Mode since they're disconnected.

Look at the diagram below to see the location of the ProTec switches. The oil pressure switch is in a "T" next to the oil pressure sending unit near the oil filter. The water temperature switch is at the left front of the intake manifold and the knock sensor is at the rear of the left cylinder head. There should be a Green wire attached to each sensor

You'll probably have to enlarge the picture some   



That still leaves the possibility that the ProTec system is on it's last legs though.

Something else to consider is that it looks like you've gone through the fuel system with the exception of the fuel pump and the fuel line from the tank to the pump.

If you've ruled out limp mode and think it's gas related, maybe it's time for a fuel pump replacement or rebuild and make sure your suction hose isn't restricted in any way.

On these older boats, you may want to consider changing out both the sending unit and the fuel gauge. On my 1994, I pulled the fuel tank and replced both the sending unit in the tank and the fuel gauge at the dash. For me it was peace-of-mind. If you do change out the fuel sending unit, I recommend the "reed" style vs. the arm-and-float type. You simply measure the height of the fuel tank where the sender is mounted and subtract 1" to get the sender length.

JQ