Carburetor fan possibly drains battery below 12v - ever happen to anyone else?

tvmaster

True Classic
It's possible that the W-D mechanics may not have entirely understood the car fan functions and consequently may not have installed the carb fan's temp switch in the correct location.

You should probably ask someone with a '74, or perhaps any year with a stock carb fan setup, to post a pic of where their carb fan temp switch is mounted. I'm guessing it's been mounted somewhere where it has no trouble getting hot but not where it can get cooled by the fan. Since the purpose of the fan system is to cool the carb, I would think the stock location for the temp switch would be within inches of the carb.
It seems to be where it it is in the manual: at the base of the carb, center, screwed in. But whether it’s functioning normally, that’s a test I’ve yet to do. But couple with what appears to be a new, faulty alternator/charging system, there’s no way I’m going very far if the fan stays on for mor than a few minutes - the battery just isn’t getting charged high enough…
 

Dan Sarandrea (Phila)

Waitin' On Parts...
It seems to be where it it is in the manual: at the base of the carb, center, screwed in. But whether it’s functioning normally, that’s a test I’ve yet to do. But couple with what appears to be a new, faulty alternator/charging system, there’s no way I’m going very far if the fan stays on for mor than a few minutes - the battery just isn’t getting charged high enough…
if it's mounted as in the pic that NEG posted, that blows my theory to smithereens! LOL

It's the exact same type of switch as used in the rad to turn the rad fan on and off, but may or may not be the same temp range. These do go bad and changing it out seems like it ought to be a pretty straightforward task.

I think you have a charging problem as well. Charging system issues can only be a few things: battery, alt, regulator, and wiring. If you suspect the battery, pop it out and bring to a local chain parts store for a free test. You already tested the system output reaching the batt and it was 12.12 which is way low, generally you want to see 13.6+. The question is how much is the alt putting out, and that would be answered as previously posted by checking the batt terminal on the alt---how accessible is this on an early X? If it's putting out 13.6+ then your problem is elsewhere, probably in the wiring between the alt and the battery.
 

tvmaster

True Classic
The open circuit voltage of a 100% charged lead acid battery is typically in the 12.9 - 13.2 range so the voltage is about right. You can check the battery condition with a hydrometer. They are under $10 at most auto stores. Charge it first.

Your multimeter should be fine for checking the alternator. Just put it on the correct DC voltage range, connect the ground lead to chassis ground, and the hot lead to the stud on the back of the alternator with a big wire going to the starter. Some alternators have a removable plastic cap on the terminal to help keep it from getting shorted when you drop a wrench down there. Remember, the other end is connected to the battery so power is there even with the engine off. It would be best to use some clip leads so you don't have to keep your hand in there with the engine running.
"and the hot lead to the stud on the back of the alternator with a big wire going to the starter" - so my hot (red) meter hooks to this connection, leading to the starter. Simple enough. In a perfect world, what should I be seeing, voltage-wise, if this connection is functioning correctly?
 

rx1900

1981 X1/9
"and the hot lead to the stud on the back of the alternator with a big wire going to the starter" - so my hot (red) meter hooks to this connection, leading to the starter. Simple enough. In a perfect world, what should I be seeing, voltage-wise, if this connection is functioning correctly?
With the engine not running...you should see same voltage as at the battery.....about 12.5 v or so

With the engine running at 2500 rpm or so....you should see 13.5 to 14.3 v or so

If not...something is wrong..........
 

tvmaster

True Classic
With the engine not running...you should see same voltage as at the battery.....about 12.5 v or so

With the engine running at 2500 rpm or so....you should see 13.5 to 14.3 v or so

If not...something is wrong..........
With the alternator, as opposed to the voltage regulator or wiring?
 

rx1900

1981 X1/9
Yes, had a 61amp Bosch with internal regulator put in
Aha.....well then.....the wiring is very simple then.

Stock on your '74 would have been an alternator with an EXTERNAL voltage regulator that was mounted on the firewall. So...converting to an internally-regulated alternator would have required some wiring changes done properly......

On your new alternator....there should be a little wire going to it - likely to a spade terminal - coming directly from the warning light on the dash. And a big fat wire from the big post on the alternator - usually a stud with nut - to the starter That is all there is to it !!!

Surely...a new alternator would have been tested at the factory...so likely not at fault here. So..either the fat wire to the starter is no good....or that little wire is not correct...

Perform that test I said above...we'll go from there........
 

tvmaster

True Classic
Aha.....well then.....the wiring is very simple then.

Stock on your '74 would have been an alternator with an EXTERNAL voltage regulator that was mounted on the firewall. So...converting to an internally-regulated alternator would have required some wiring changes done properly......

On your new alternator....there should be a little wire going to it - likely to a spade terminal - coming directly from the warning light on the dash. And a big fat wire from the big post on the alternator - usually a stud with nut - to the starter That is all there is to it !!!

Surely...a new alternator would have been tested at the factory...so likely not at fault here. So..either the fat wire to the starter is no good....or that little wire is not correct...

Perform that test I said above...we'll go from there........
And here's the result:

Battery before test: 12.37v

Battery with negative meter to bare metal frame and positive to BIG stud: 12.37

Battery reading with engine started: 3k rpm: 12.09v 1k rpm: 12.06v

And now, the 'G' light has gone dark - although the car starts and runs fine - possible blown bulb from short while doing test?

But if that's the case, if the bulb was blown, wouldn't the car be unstartable?

regardless - these readings are not promising....
thoughts?
PS: this is a rebuilt alternator, not a new one from the factory
 
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rx1900

1981 X1/9
And here's the result:

Battery before test: 12.37v Okay that is good

Battery with negative meter to bare metal frame and positive to BIG stud: 12.37 Okay that is good

Battery reading with engine started: 3k rpm: 12.09v 1k rpm: 12.06v Are those readings at battery ? Or at big alternator stud ? You need those readings at the big alternator stud


And, now the 'G' light has gone dark - although the car starts and runs fine - possible blown bulb from short while doing test? See below

But if that's the case, if the bulb was blown, wouldn't the car be unstartable? No...car would still start...

regardless - these readings are not promising....
thoughts?
PS: this is a rebuilt alternator, not a new one from the factory
Okay good...now we are getting somewhere. :) But it is clear that your battery is NOT getting charged from the alternator like it should !!

See comments in blue above.

But first off......when you turn the key to the "on" position..before you start the engine.....the G light on the dash should be on brightly. Is it ? And should go off completely when you start the car and the engine is running ?

New or rebuilt alternator...either would have been tested at factory....so unlikely at fault...
 
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How is your ground strap? It might be interesting to measure the voltage between the alternator output stud and the alternator case with the engine running. If that voltage is different than what you measured against chassis ground, there may be too much resistance between the engine and the chassis.
 

rx1900

1981 X1/9
Hey...a pic of the back of your new alternator all hooked up might be helpful here for us...

But in any case......i'm starting to think that little wire on the back of the alternator is not hooked up correctly. But easy to check....assuming the G light comes on when the ignition switch is in the "on" position - and car not running - then simply....with key still to "on" position.....pull off that little wire on back on alternator.....then light should go off. The push it back on and light should go on again. Try that.......
 

tvmaster

True Classic
Hey...a pic of the back of your new alternator all hooked up might be helpful here for us...

But in any case......i'm starting to think that little wire on the back of the alternator is not hooked up correctly. But easy to check....assuming the G light comes on when the ignition switch is in the "on" position - and car not running - then simply....with key still to "on" position.....pull off that little wire on back on alternator.....then light should go off. The push it back on and light should go on again. Try that.......
Did you see in my post where I said the 'G' light has now disappeared altogether, whether the engine is running or not? No G light at all - black, dead, nada. The rift of life.....
 

tvmaster

True Classic
How is your ground strap? It might be interesting to measure the voltage between the alternator output stud and the alternator case with the engine running. If that voltage is different than what you measured against chassis ground, there may be too much resistance between the engine and the chassis.
So black (negative) goes to the alternator case then?
 

rx1900

1981 X1/9
Did you see in my post where I said the 'G' light has now disappeared altogether, whether the engine is running or not? No G light at all - black, dead, nada. The rift of life.....
Well.....testing with a meter would not have blown that bulb. But yes.....that bulb should be working as indicated...on when key is in run position but car is not running....and should go off when car is running...

Whatever....if you are only getting 12.09v at the battery when car is running at 3K....then the alternator is NOT charging as it should.

Check the G light bulb and its wiring and fuse.

Check with wherever you got the new alternator from to see how it should have been wired up...and check that....My best guess is that you dont have it wired up correctly.......
 
I was just going through the Fiat factory manual and noticed that in the Electrical Troubleshooting section (page 221) they have diagnosis procedures for electrical issues you are having (no GEN light and poor charging). You might want to go through the step by step processes in there to figure out what the problems are.
 
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