Onemoparnut

Ok so yesterday i put a new belt and tensioner on my heap and now the charging system is pulsing. That was the only thing I messed with and I had to unbolt the alt so I could get the belt on. I had to unbolt the alt cause the belt is a little short and there wasnt enough throw in the tensioner. But this is not a new situation with the belt. When I rev the truck over 1500 rpm it seems to smooth out the pulsing some but it is still there. When the truck Idles it is really bad and driving me nuts. If I turn the ac on with the fan on high and my electric fan on at the same time it also smooths out some then.

My second question is a problem that I have had for a while. When I fill the fuel tank the gauge goes haywire. it will go from full to empty and anywhere in between at will. The gauge will move very rapidly all over. Then when i get about 50 miles in the full tank it starts working properly and reads between full and 3/4 tank. When I run wmo the gauge hardly works at all.

wannadiesel

Sounds like alternator trouble. Check for AC voltage on the output.

The fuel sender is dying.

Onemoparnut

What do you mean check for ac voltage on the output? How do I do that?

wannadiesel

Set your meter to AC and put it between the alt. output terminal and ground. I have seen as bad as 27 volts. That Taurus didn't run well...

Excessive (more than a few volts) AC voltage means that the rectifier is shot

Onemoparnut

Ok I will check it out in the morning thanks alot wanna. I can actually hear a rythem in how the engine idles that is in sync with the fluctuation in the lights.

Onemoparnut

Ok I checked what you said Faith. I hooked the red lead to the heavy single wire connection on the back of the alt. The black lead I hooked to the negative terminal on the battery. There was like a 6 volt spike when I first touched the battery terminal then it fell to .5 volts. When I unhooked the lead off the battery it also had a quick voltage spike up to as much as 22 volts. But I left it hooked up and it stayed at .5v. It was like there was only ac voltage there right as I connected and disconnected the test leads from the battery. Could it be that there is ac voltage but no current to sustain the voltage and the meter is getting rid of that ac voltage when I hook it to the battery???

Onemoparnut

Well I ordered a new alt today I should have it tomorrow I hope it fixes it.

wannadiesel

Half a volt is fine. I think the spike was the meter finding its range, is it an autoranging meter?

Santaclaus

Before you change alternators checked the voltage on the two small car models that lead to whatever you use for a voltage regulator. If they are pulsing you may have a bad voltage regulator. An old man once told me that you could take something like at 1157 bulb and put it in series between your positive voltage i.e. battery + any input for your field current. Of course you'll have to disconnect the two small wires and hooked the other terminal to ground. This should give you a smooth output but nowhere near full output so as not to blow anything up in the truck. So far do explain, I've used it on summary and alternator problems.

Onemoparnut

[QUOTE=wannadiesel;2813800]Half a volt is fine. I think the spike was the meter finding its range, is it an autoranging meter?[/QUOT

No it is a manual range meter I just set it for 150 volts that is the only ac setting it has.

Onemoparnut

I am confused what should I be checking?

Onemoparnut

Where is the best place to get a new voltage regulator. I know there has been a lot of controversy about them being good and bad from different places.

wannadiesel

I like OEM junkyard regulators better than parts store models.

The jolly guy in the red suit is talking about temporarily replacing the regulator with a light bulb. If the pulsing goes away, it was the regulator. If it keeps pulsing, then it's new alternator time. Ingenious!

On ours the regulator controls the ground, so if you disconnected the regulator from the alt. and grounded that terminal through a taillight bulb, you'd get a fixed charging rate that's not high enough to burn out all your light bulbs and boil your battery. It's a valid test to find the source of the pulsing and I like it.

Onemoparnut

I dont really have time to get to a junk yard till next weekend and I need to fix it before then it driving me nuts. People think I am flashing my lights at them all the time.

wannadiesel

Do santaclaus's check and see where the trouble is. If you're confused on what to do, PM me for my number and I'll talk you through it.

People have had better luck with the Duralast brand regs from Autozone than the Standard Motor Products units sold at pricier stores.