496 Mag Ho Won't Rev Up
 

I have a 496 MAG HO's I just installed in a boat and they have been sitting but properally stored. They start and act like they run fine put the motors in gear and go once they BOTH get to 2800 rpm they shut down. Its not the props just so you know it acts like a limp mode or low fuel pressure. Can anyone help with somewhere to start looking.

What percentage of power is available at start up? What about when you get to 2800? Do you for sure know the state of the fuel supply in the tank and filter(s)?

Did you put a pressure guage on it?

New filters tanks are imco's built in 08. I really think it's some sensor or wires I have hooked up wrong but not sure. No pressure gauge hooked up.

Just a thought?, did you check the oil level in the drive reseviour?, I had a similiar problem with my old heap, when the drive oil gets to a certain level in the resevior there is a sensor that limits RPM

Easy fix, so, I hope this helps!

Michael

Both motors have 45lbs fuel pressure when switch is turn on.

When your drive resivors are low you also have an alarm going off? When I first hooked up wiring res. were empty and alarm went off when I turned the switch on. Just trying to figure this out Weekend coming up on us.

Might be in guardian mode

John jr

True, I had my alarm wires disconnected [still actually trying to sort them out!] and the alarm didn't go off, have you put a scan tool on it?, any codes?

Hope you get it sorted it, there are a lot of guys on here that have forgotten more than I will ever know, so, lets hope you get some input

Michael

If in gaurdian mode wouldn't alarms go off?

Got it It was the lift pumps were bad. Thanks for everybodies input.

Check your shift interupt switches. If it thinks you are in nuetral it will do the same. Maybe they are not adjusted correctly.

What are interupt switches?

Its not really an interupt switch, but a switch that lets the engine know its in gear. 496's and 525efi's won't rev past 3000rpms in nuetral.

mine does.. :party-smiley-004:

i thought you were talking about the neutral safety switch. My other stock 496 would rev above 3000 but not a common sense practice.