Throttle Position Sensor Setting - Merc 225 - The Hull Truth

escape2theocean · 07-08-2007, 12:40 AM

What is the voltage supposed to be set at for the TPS? Mine is right at 4 volts at idle, then gradually goes down to .95 at WOT, is this ok? Thanks.

Motor is 1998 Merc 225 Offshore - Carburated (but has TPS, kinda wierd)......BTW, what does the TPS control on this motor?

timebandit · 07-16-2007, 05:09 PM

Idle speed.

timebandit · 07-16-2007, 11:26 PM

Ign. timing too.

escape2theocean · 07-18-2007, 12:16 PM

Thanks, I think mine is working ok. I learned the alarm sounds if the voltage is out of range.

rprichoux · 07-18-2007, 03:17 PM

Something is wrong here, how did you check the voltage? The voltage should be approx. .95 at IDLE and approx. 3.75 at WOT.. It should show a smooth increase in voltage as you go from idle to WOT. The TPS advances the timing as the throttle opens.

escape2theocean · 07-21-2007, 12:37 AM

voltage checked with fluke dig multi-meter, probed ground into black wire (at harness connector), and pos voltage at other wire, dont remember the color, there are only 3 wires, the black is ground......I thought it should be the other way around. I will check again tomarrow to make sure im not going crazy here.

escape2theocean · 07-21-2007, 12:38 AM

Quote:

rprichoux - 7/18/2007 2:17 PM

. The TPS advances the timing as the throttle opens.

Shouldn't it retard the timing as it approaches WOT though?

escape2theocean · 07-21-2007, 05:45 PM

My TPS definately reads 4 volts at idle, then decreases to .95 volts at WOT. ground to black wire, pos volts to black w/blue stripe center of 3 pin connector.

timebandit · 07-22-2007, 10:24 AM

Thats OK. Merc did it both ways. It might be inverted on that engine.