Ok so Ive posted on this a few times, and it seems like I never really got a chance to get going on the testing.

(original threads https://www.ford-trucks.com/forums/7...-runs-dry.html
https://www.ford-trucks.com/forums/7...ery-drain.html)


Problem is my battery goes dead. The battery tested out good a few times on a load tester, and it stays charged without the cables on it. (reads 12.70 or so volts) Ive tested it a few times over the past few days (after fully deep charging it) and the battery stays right around that range.

Ive tested the alternator just at home with my DVM and it tests 14.85ish while running, telling me my alternator is charging.

Ive taken the neg battery clamp off and hooked up a test light, no glow (not even a slight one) I have no radio in it right now, so the computer would be the only thing drawing power)

I hooked up my DVM between the neg post, and the clamp, set my meter to the setting 20m/10a and Im positive I have the prongs in the right place (got the meter given to me, no instructions and Im not familiar with this one)

The reading I am getting on that setting is first 10.xx then after a second or two, it reads 3.xx. I am assuming that means milliamps.

Not sure what to check next. Since I have no bright light coming on when i do this test, should I go and start pulling fuses anyways? Im not 100 percent sure on what my DVM is telling me when it reads a 10.xx reading, then drops to 3.xx. Is that reading in milliamps?

Thanks for any help I can receive on this, and forgive my ignorance on the DVM.

 

Speaking from personal experience when I had a battery drain problem it turned out to be the regulator inside the alternator. The alternator tested fine on one of those benchtop electrical testers at an autoparts store, so that tells me they aren't setup to correctly test the integrated regulator/rectifier in these Ford alernators. Have you tried another alternator?

 

No Paul I havent tried another alternator yet. Its beautiful out here today, and I do have a parts truck with an alternator on it, so maybe ill throw that on there and give it a shot.

Around the year 2000 or so I was using this truck as my main daily driver, and the alternator wouldnt charge, so i replaced the brushes in it, and it started working again, so that was the end of that.

Is there a way to actually test the regulator's? Can you replace just them? I never looked into that yet.

 

Just giving my self a bump, looking for anymore opinions, suggestions. I swapped out the alternator and tested the battery, and it doesnt appear to have drained. Last night i checked it and about 7 hours later i checked it and i had the same reading.

 

So no battery drain = problem fixed doesn't it?

 

Well Im not too sure yet haha. I did fully charge the battery and Im not sure how much of a timeline I used to let it sit for before the battery would drain. I always say overnight, but sometimes it took a few days then overnight.

So yeah so far it seems to be good, but just looking for anything else, that anyone has to say

 

I have narrowed my battery drain to a stuck eec relay, .38 with relay in and 0 with it out

 

Where abouts is the eec relay?

My truck ended up being fine for around the yard. I took it to the dump, shut it off for a minute, and the battery was dead, almost like something drained it on the way to the dump. I had let it sit for a week before starting it up, and it started fine. It only died after the 6ish mile trip to the dump.

So changing the alternator fixed my problem for abit, till I actually drove the truck somewhere.

 

on my 88 its beside the air cleaner,theres a green case with the fuelpump and eec relay together. mine all coroded ill post back if it fixes it

 

Confirmed the eec relay or the plug was my problem,no draw and no fuel pump prime when i hooked up the cables. 24.00 fix for relay and new plug from napa. 5 minute wiring job and its dun

 

Thanks for the update man, i will check into mine.

 

does ur fuel pump prime when u hook up the battery terminal?

 

What a coincidence... I had mysterious battery drain as well, on my 91 F-150 and while poking around with the hood up not 5 minutes ago my fuel pump relay starts cycling on and off with the engine off! So it will be replaced today.

 

Where did you get the alternator from? I had this problem it would start and run fine around the yard but when I drove it somewhere and shut it off the battery would be dead. Turned out my NAPA remanufactured alternators (went through 3) were all put together wrong! They put the voltage regulators in the wrong clock position. Im no electrical expert so I took it to an electric shop and the techs told me this. They reassembled it correctly and the problem quit.

 

Ok, my problem is now fixed. As it turns out, the culprit was a corroded ECM relay under the hood. After the ignition was turned off, it started sending an intermittent signal to my fuel pump relay (right next to it) which primed my pump on and off over and over again until the battery died. $20 and 2 relays later no problems! It's even running better...