120 Ford Lehman RPM issue

[wallabyshane]

Hey all,
My RPM on my 120hp Ford Lehman has stopped working. Can anyone tell me what this is called please? It may be the issue.
TIA

 

[Toadhall]

Pretty sure that’s your oil pressure sender.

Rpm probably comes off your alternator.

 

[wallabyshane]

Thank you.

 

[meridian]

Is your alternator working? Any charging voltage?

 

[wallabyshane]

Yes.

 

[motion30]

My 1973 120 Lehman had it tach Drive sensor and did not register off the alternator

 

[wallabyshane]

Thank you

 

[SeaMoose]

Most likely the tach will have three wires going to it. One ground, black. One wire for the light, should be brown. The third wire is the rpm wire that goes to the alternator and most important will likely be the same color all the way to the tach.

If you have a voltmeter it’s A/C going to the tach.

Tachs do break. Do you have upper/lower helm stations?

 

[wallabyshane]

Most likely the tach will have three wires going to it. One ground, black. One wire for the light, should be brown. The third wire is the rpm wire that goes to the alternator and most important will likely be the same color all the way to the tach.

If you have a voltmeter it’s A/C going to the tach.

Tachs do break. Do you have upper/lower helm stations?

Yes. Both upper and lower helm stations neither of which the RPM is working. I'll have a look at the wires you described. Thank you. Appreciate it.

 

[CEC]

The wire on the top left back of the alt (looking at from the back) providing that's where your sender is setup from and not the other types. That connector gets loose and sometimes breaks - needs fixing. The good news is if your motors running you have RPM's

 

[wallabyshane]

The wire on the top left back of the alt (looking at from the back) providing that's where your sender is setup from and not the other types. That connector gets loose and sometimes breaks - needs fixing. The good news is if your motors running you have RPM's

Perfect. Will have a look. Thank you.

 

[Mkeller]

Check that the oil pressure switch controlling the alternator is closing.

 

[wallabyshane]

Will do. Thanks.

 

[Xsbank]

Wallabee, that is the most disreputable sender ever seen on this site!Welcome!