Vacuum erratic when electric fans turn on

[forestb]

Thank you. Yes I have an aftermarket wiring harness

[forestb]

So I looked though my old paper work. And this is the alternator that I have and this is the installation manual from powermaster. I was looking on the mad electrical website and it looks like this is the wiring harness that I need.
http://www.madelectrical.com/catalog/alt-1.shtml

[The Rocknrod]

Just ensure post 2 is connected far from the alt, nearest the battery. Not to the battery charge post on the rear of the alternator.

[forestb]

My plan is to order the harness from mad and use their instructions.

[forestb]

I am still wondering if this problem could cause my engine to intermittently stumble during acceleration.

[67 Burb]

Besides the vacuum dropping and the gauge needle bouncing around, does the idle speed change as well?

Figure out the low voltage problem first and see what happens then.

[forestb]

Originally Posted by 67 Burb

Besides the vacuum dropping and the gauge needle bouncing around, does the idle speed change as well?

Figure out the low voltage problem first and see what happens then.

I will take a look but it doesn't seem like the idle speed changes. But I have not checked it by looking at the gauge.

[forestb]

I got an email saying that 67 Burb posted a longer reply than the one he did in post 31 but it has disappeared. Was it removed or edited or something?

[67 Burb]

Originally Posted by forestb

I got an email saying that 67 Burb posted a longer reply than the one he did in post 31 but it has disappeared. Was it removed or edited or something?

Sorry, I had composed a long reply, but it took me so long, that when I went to submit it I realized there were other replies that covered much of the same stuff I did, so I posted a shorter version.

So has it been established that you do not have a one-wire alternator?

[forestb]

Originally Posted by 67 Burb

Sorry, I had composed a long reply, but it took me so long, that when I went to submit it I realized there were other replies that covered much of the same stuff I did, so I posted a shorter version.

So has it been established that you do not have a one-wire alternator?

I have an alternator that can be either used as a one wire or a 3 wire. It is currently set up as a one wire.

[67 Burb]

OK, that's good to know. What my concern was, that you were measuring 12 volts at the distributor. With the engine running, you should be getting a higher reading, in a range of 13.5 to 14.5 volts. also check voltage at the BAT connection on the back of the alternator.

Some one-wire alternators will not put out any current after the engine is started and then just running at an idle and need to be revved up before they "kick in", so after reading the voltage after starting the engine, rev to 2000 or 3000 RPM and check the voltage again.

I have a one-wire alternator on one of my cars, and I had to rev the snot out of it to get the thing to charge. I ended up installing a smaller diameter pulley.

You probably haven't noticed any problem with the battery keeping charged because once you start driving the alt kicks in.

I feel that somehow this situation is caused by the low voltage you are seeing at an idle.

[forestb]

Originally Posted by 67 Burb

OK, that's good to know. What my concern was, that you were measuring 12 volts at the distributor. With the engine running, you should be getting a higher reading, in a range of 13.5 to 14.5 volts. also check voltage at the BAT connection on the back of the alternator.

Some one-wire alternators will not put out any current after the engine is started and then just running at an idle and need to be revved up before they "kick in", so after reading the voltage after starting the engine, rev to 2000 or 3000 RPM and check the voltage again.

I have a one-wire alternator on one of my cars, and I had to rev the snot out of it to get the thing to charge. I ended up installing a smaller diameter pulley.

You probably haven't noticed any problem with the battery keeping charged because once you start driving the alt kicks in.

I feel that somehow this situation is caused by the low voltage you are seeing at an idle.

Ok I will try and check that after I get home from work tonight if it is still light outside.

[forestb]

So I took some more readings after reving it up to 3000 rpm with the engine still running.

12 volts at distributor.
12 volts at alternator post.
12 volts at battery.

In 2019 when I took readings with the same one wire alternator it tested.

Checked battery while not running.
12.7 volts at the battery
12.7 volts at the starter
12.7 volts where the ground attaches to the block

Checked battery while running
14.4 volts at the battery

Checked battery while cranking
It went down to 11.4 volts.

[forestb]

So I was thinking could it be that using the one wire alternator for the last 3 years has weakened my battery? Even in 2019 when I took those readings I was still having problems with the engine stuttering during acceleration.

[67 Burb]

Sounds like your alternator has a problem.

[forestb]

Do you mean the alternator itself or the way it is wired?

[67 Burb]

Hard to say. You need to find someone who knows his (or her) way around the wiring system.

If I was just down the street, I'd be there in a minute. I just checked our weather here and it's -29°C (-20°F), I'd much rather be in Burbank.

But Brandon, Manitoba is a long way from Burbank, CA.

[forestb]

I guess getting the alternator and the battery tested would be a good first step.

It was around 75 yesterday. We get excited when ice forms on the car window overnight. I can’t even imagine what anything below 0 feels like

[forestb]

It looks like my battery is around 3.5 years old. I wonder if that could be my problem. I should have it tested.

[Bigdav160]

One wire alternators require a large, at least 6 gauge, output wire to be able to respond to the load effectively.

If you're using the factory output wire it's way too small

[forestb]

It is a fairly thick wire I am not sure of the gauge but it is around 3/8 in thick including the coating.

[forestb]

What is interesting is that I am getting around 14 volts at my Voltmeter gauge

[forestb]

Originally Posted by The Rocknrod

I would ensure there were grounds to everything including the alternator to motor and motor to battery, If you radiator support has anything ground to it then by all means that needs a clean ground, including frame, body etc, etc. You can't have power if you don't have grounds.
As far as your alternator please read this article on alternators - http://www.madelectrical.com/electri...hreewire.shtml
They work!

Be careful if you call this guy to order a wiring harness (you can only order by phone). I spent the last hour learning about the shortcomings of automotive wiring for the last 60 years. This guy is a fountain of information. In the end he did not recommend that I switch over to a three wire wiring setup. But he did recommend that I read a few of the articles that he wrote on his web sight.

[RustyPile]

Originally Posted by forestb

I have an alternator that can be either used as a one wire or a 3 wire. It is currently set up as a one wire.

I read the information about your alternator at that web site. I have trouble believing that alternator can be wired for either one wire or three wire operation. I have some
experience with those one wire alternators, and personally, I wouldn't put one on anything I own. Having said that, I don't see how a one wire unit can be also wired up three wire.. The voltage sensing is done internally. And that would have to be converted by installing a conventional "3 wire" voltage regulator.

Also, it's not a good idea to depend solely on the in dash volt meter. They are notoriously famous for their inaccuracy. Use a DVM for taking voltage readings..

[forestb]

All that I know is that I used the alternator as a 3 wire when I first bought it in 2009. I then started using it as a one wire around 4 years ago. When I was running it as a 3 wire I had removed the external regulator and put an adapter on on the plug that used to plug into the regulator that rerouted those wires.

I do understand that the voltmeters are not vary accurate. What is a DMV?

I had the battery checked today and it was still in good condition. I took the alternator to get tested but they could not figure out how to hook there Machene up to it. I did notice that when I reinstalled my battery that positive battery cable sparked a little when it touched the post. I have heard that this might mean that I have a ground problem. Also maybe I just need a new alternator sense mine is now 13 years old.