Wrong alternator? (1 Viewer)

[MoabChris]

Having some electrical issues. And I diagnosed that the alternator gone bad. So I went and purchased a replacement and installed it no more belts squealing. However after installing the new alternator the voltmeter was only reading 11 volts. This was while the car was running so did I install the alternator incorrectly or is it the wrong size alternator because I just realized they were two versions for the fj40. it's a 1976 with a Chevy small-block V-8. It had a 55 amp alternator stock Toyota and I replaced it with the 45 amp version accidentally.
How significant is in the 10 amp difference in the two alternators production?

 

[1911]

Is there a difference in the alternator pulley diameters?

A 10-amp rating difference shouldn't have anything to do with the output voltage.

 

[thebigredrocker]

There was some discussion of alternator output recently and also external voltage regulator adjustment: pages 64 - 66
76 Fj40 Face Lift

 

[Coolerman]

A 1976 would have an externally regulated alternator. So you may have a bad voltage regulator. What does the amp meter show when running?

 

[MoabChris]

No the pulley diameters were the same...

 

[MoabChris]

A 1976 would have an externally regulated alternator. So you may have a bad voltage regulator. What does the amp meter show when running?

Around 11 AMPs

My son took it too work Saturday and after he got there it would not start again ( dead battery) until it was jumped.

 

[Coolerman]

11 amps? + or - ?
Has to be minus or the battery would be charging.... Still 11 amps is one hell of a lot of current to be pulling. What all was on at the time?

 

[MoabChris]

Not sure if it's working...but here's what's it is showing while running.

Also, if i disconnect the battery while the vehicle is running...it immediately dies...

 

[MoabChris]

Sheepishly....
The alternator connection plug came undone....
Problem solved....

 

[Coolerman]

Happens to the best of us... Congrats though for sticking with it until you found the issue!

 

[MoabChris]

Thanks! I have to learn to trust the gauges....the low voltage and the negative amp draw while running should have clued me in that that the alternator wasn't sending power into the system.

Live and learn.
Now onto some more upgrades...and stuff. Replace the dead wiper washer fluid motor, install the fusable link, replace the non functional oil pressure gauge, investigate the very dim instrument cluster light bulk, check the brake pads and rotors.... wahoo