96 Speedster Tachometer Problem

[Mooze]

So the tach on my no. 2 eng does not read. I connected it to the number 1 side it reads. (So gauge is good) The eng when running in neutral will not run full speed. (eng is sending the rpm signal to mpem) I checked the continuity from Pin W in the cannon plug to tach connection and it is good.. So I am assuming somewhere in the mpem to the cannon plug is bad? I haven't opened the grey box as I am neverous about getting in there and breaking a discontinued part

Any suggestions on how to go about fixing it..... OR is there a way to run a new tach and wires?

Thanks

 

[Dr Honda]

Boats have a neutral switch... and they only run to 3500 RPM if they aren't in "F".


The tach will read a simple signal from the charging coil. SO... make sure things are connected... and make sure that engine is putting out a charge.

 

[Mooze]

Yeah about the neutral switch, I figured because the engine IS limiting to 3500 rpm in neutral, that the engine is sending the RPM signal to the computer.. So that wiring should be good.. I did a continuity check from the grey box cannon plug "PIN W" to the Connector under the front hood.. That read 0 ohms, so no break in that wire.. The Gauge I hooked to the other side and it worked, so gauge is good..

So could it be somewhere in the MPEM that is bad? I haven't opened the grey box. If that is the case is there a way to run an aftermarket tach system from that engine?

Sorry if my original post wasn't clear.

 

[Dr Honda]

I would have to double check the wiring... but on the 720 engine... the MPEM doesn't send the tach signal to the gauge. You just have an open wire somewhere.

 

[Mooze]

Okie dokie.. Ill look at it again once i get my top end back from full bore... I really want that tach.. MORE than any other gauge

Thanks again!

 

[Mooze]

Ok so I checked the wiring in the grey box. Seems that it all looks good. I ran continuity checks and those check out good. The eng is limited when in neutral which leads me to believe the wires from the eng to box are good. I did notice two separate little electrical boxes in there that each eng connects to before (or in conjunction) before the wires run out to the tach.. Could that little box be the problem for my number 2 eng tach not working? Is it the rectifier?

 

[Dr Honda]

Don't know... post a pic.


The 720 tach normally just pulls a signal from the stator. (off the power side) So... yes... it could be the regulator.

 

[Mooze]

Well.. Figured out my problem... Damn 15 amp fuse... after looking through the wire diagrams with a fine toothed comb I seen that damn fuse this time around! pulled the cover and checked it.. Ill be damn if it wasn't blown... So I was semi-right.. It was the rectifier, but it wasn't the rectifier itself haha just the power to it! There you you have it.. So at least all my other trouble shooting was in fact right.. It turned out to be nothing I had already checked hahah! there is a bright side to everything!