Expert: tyler boehner - 2/16/2008

Question
I have a 2000 Mariah 244 jubilee with a Mag 502 EFI w/ a bravo 3.  Lately ive been having problems when driving.  if im driving full out after a little while the boat loses all power and slows down no matter how far the fuel lever is pushed.  Then after a while it will begin to speed back up.

Ive been doin a bunch of work to the boat including a new starter, all new fluids, tune up, coolent sensor, and a new tps.

When installing the tps there are 3 wires: a black-ground,
a white and a blue.  The white is supposed to be a constant 5 volts, but for some reason it is only reading 2.18 v.

Any ideas why this would be?  And if this would be the problem with the loss of power or how to fix it?

Thank you for your time.
Eric

Answer
I don't know the specifics about the voltage readings of the tps.  When it comes to anything with a spec, we usually go to the book and follow that.  Ignoring the tps, first place that I would look is at the fuel pressure.  Make sure your fuel pump can keep up with the demand of wide open throttle, and make sure you don't have an air leak somewhere in your fuel system.  It sounds to me like the engine is starving for gas after running wide open for a while.  Slow it down for a little while, and the pressure will build back up and you can run wide open again.  Second thing to look at, which you can't do on your own, but if the boat was at a merc shop, they should have a cds.  This is a computer that will tell you if your engine is going into guardian mode making the engine run slower to protect itself and what your fuel pressure is running.  It will also tell you what your tps is reading.