Hi guys, I've got an E250 that won't charge. With the enine off the battery reads 12.6 volts. When it's running the voltage drops to 11.89. It stays pretty steady even when I rev the engine. I noticed this when my amp light came on at start up and my wipers were slow. I put my test lead on the post on the alternatir and the negative lead on the alternator housting and got the same readings. I had the alternator tested and they said it was putting out 14 volts. I Google this and got quite a few suggestions. One is that the belt may be too loose. I did notice that the serpentine belt can be removed with using the tensioner. Another suggestion was the mega fuse, but I've not been able to locate it if this fmvan even has one. I'd appreciate any thoughts

 

That bench test you had done is suspect, I have seen first hand where they said an alt was good only to have the problem fixed with a new unit.

 

HI Conanski, thanks for the reply. I suspect the test also. I saw online that with the multimeter''s positive lead on the post of the alternator and the negative lead on the housing I am getting a reading straight from the alternator and that if it wasn't getting 13 volts or more the alternator was bad. With the engine running it's reading about 11.89.

I did notice that the serpentine belt can be taken off with just my hand by sliding it off of the idler pulley so I think it's a little loose. I saw that this could be a cause due to belt slippage. However, I wonder because there is no change in voltage when I rev the engine.

 

Yeah the belt should not come off that easy, either your tensioner is seized up or the belt on there is just too long. Does the tensioner move freely, if you put a wrench on the pulley bolt on the tensioner you should be able to articulate it some without too much force.
If the belt was slipping you would hear some squealing I would think.

 

With your direct test, the alternator is showing bad.

If your belt is that loose, it could be the idler as Conanski wrote, or the belt could be "stretched" out from wear.

One other thing not to over look, is the battery connectors.
You didn't post the year of your van, but over time if it has the crimped on lead connectors, the wires inside the connector become corroded and will cause problems, good fix is to replace the connectors, See this.

 

The tensioner was stuck. I loosened it up, but it'll need to be replaced. It did put a lot more tension on the belt after I loosened it up. However, that didn't solve m problem.

 

That's what I thought. I had the alternator tested again at a different location and it passed again. However, as I said when I put the meter from the post to the housing I get 11.9 volts. I had them test the battery too and they said it was good, fully charged.

It seems like the alternator isn't coming on so I thought maybe it wasn't getting power from the exciter. I'm not really sure how that works but I took a reading from the plug with the three wires that connects to the alternator. I got 12 volts from the each outside pin when I put the lead on the pin and the negative lead on the housing of the alternator. I got nothing from the pin. I guess that means that the alternator is receiving the necessary 12 volts to get started. I'm really stumped.

 

I don't think your testing the alternator correctly. You don't test off the 3 wires, you test off the one Alternator output stud (cable) Or I'm reading you wrong???

Here's a Link for testing the alternator/battery.

That test is for a '97 - '02 F150, 4.6 or 5.4 but it's a "general" test.

Again, you did not post the year of the van in question.

You wrote that you found the belt tensioner hanging up, that would cause the belt to slip 'under load' and solve some of the problems.

 

HI Wildman,

Sorry, the van is a 95 E250 with 5.8 liter. When I spoke about checking the three wire plug I was referring to the exited voltage. I saw that the alternator needs 12 volts to excite it or turn it on. I thought maybe the reason it wasnt charging is because I t wasn't getting this 12 volts to excite it. When I checked whether or not it was charging I used the stud on the back where the battery lead connects.

I freed up the tension so that it is putting pressure on the belt. I am no long able to move it with my hand. I don't think the tensioner is the problem.

I looked at the link you sent. I will have to try to find those two fuses. I looked for the mega fuse already but didn't find it. Thanks for these help!

 

I think if the dash gauge works you can assume the inline fuse is good because if it wasn't the gauge wouldn't register. These alternators have an integrated rectifier and voltage regulator and one of those are most often the cause of charging problems, The regulator is relatively easy to change but the rectifier isn't, so I suggest you just change the whole unit.

 

Butch, the others have steered you in the right direction and a simple alternator R&R will likely fix you up. I have a 1994 Ford Electrical troubleshooting manual and there should be very little change in the '92-'96 family. I've attached the entire section for Charging System and it's overkill for what usually boils down to the Alternator or internal regulator, but there are some fusable links to be aware of and some other possible "head scratchers" that it should address. Hope your fix goes quick & smooth. Jeff

 

After reading your post I was thinking, I'm not sure if the light came on yesterday when I turned the ley. When I first noticed the problem the light (picture of battery with the word amps in it) was flickering and the wipers were slow so I shut the engine off. When I was working on it yesterday I don't recall the light coming on when I turned the key to the on position.

 

Thanks Jeff, I'll have to look at it after work!

 

Totally agree.

Another 15 posts about testing, and that time could be used to R&R this.
And now that we found out that this is in a '95, I'm sure if this is an OEM , at 22 years, it's time for a change.

You will not find the 2 fuses in a '95, like I posted, that's for '97-'02 F series, and actuality from '98+ E series.

That's why posting the year, engine, and mileage is important when asking questions about any trouble-shooting.

 

The alternator isn't original. It's been replace with
in the last three years. I realize the engine info is important, I just ovelooked posting it. It seems to me that either the alternator is bad, despite the tests, or it's not getting the voltage it needs to start charging. Would you agree?