1994 f1150 5.0 4x4 I just had the hood open on my pickup for 30-45 mins while I changed the radiator and when I went to start it afterwards it would barely turn over and wouldn't start. When I put the volt meter on it, it read 11.5 volts. I threw it on a ten amp charger for ten minutes and it started right up. The darn thing has done this to me before and I chocked it up to bad batteries until two years ago I ran into the store and left it running and when I came out it had died. I got a jumpstart to get home and put a new alternator on it the next day. I believe I put a new Interstate battery in it at the same time. Last winter whenever I wanted to use it I would have to put it on the 10 amp charger and it would start right up.

Since July, I've been driving the pickup everyday to work and around town and it has been fine as far as starting goes. My voltage gauge moves around a lot. If its running at 1500rpm or above I can run my headlights, wipers, and heater full blast and the voltage stays up, but as soon as it drops below that it really starts to drop. Idling at around 800rpm with just the blower motor running it drops into the mid 13's and if I turn on the headlights just on dims it will drop to 11.5-11.6. I put a new motor in it in June and the back cover of the voltage regulator got cracked, but I didn't think it hurt anything tho.

Where do I start? I've really thought about just upgrading to the 160 amp alternator from rjm injection, putting in a new battery, and putting in new battery cables, but with Christmas right around the corner I still have a ton of gifts to buy and don't want to just start throwing money at it.

 

Sounds like a bad regulator and/or a corroded chassis or engine ground.

 

I looked around and I can get a new voltage regulator here in town for around $25, so I think I will change that. Ill check the grounds too. I might just go ahead and change the negative battery cable and clean up where it goes to the block too.

 

Well I put a new voltage regulator on just a bit ago and yesterday I had a new negative battery cable made and cleaned all the contact points for it with wire brush......its still doing the same thing. the brushes that you see when you pull the voltage regulator out still had a lot of material left, although they were a bit grooved, one a little more than the other. Any ideas?

 

My trucks have had probkems like this. I would have the the auto parts store do a draw down on the battery, then have then check the alternators output so you know your getting power back to the batter to charge it... Lastly, add another short ground cable to your fender... Sometimes a ground to the block isn't enough... there are plenty of others on here that will attest to bad grounding problems... this is why i have 2 grounds on all my trucks!

 

Well the negative cable goes to the block, frame, and fender already. I'm not sure how much another ground will help. I suppose it can't hurt anything tho.

 

ok well you probably don't need one then... the older 87-91's have a cable that is split in the middle to ground to the frame and then off to the starter... after 20 years the split in the cable rots out and people usually change the cable with one that only grounds to the alternator... that's why it's good for us with the older pickups to get a marine terminal and run 1 wire to the block and 1 wire to the fender... I'd go with checking the alternator next. do you have a G2 (external fan) or G3(internal fan) alternater?

 

I has the 3g alternator.

 

Took my alternator back off and had it tested........they said it was putting out 8.3v at idle speed. Only around 5,000ish miles on the alternator, but its 2 or 3 years old, so I'm sol. I'm thinking of an alternator upgrade to either a 130 or 160 amp.

 

You should be able to find a 130 amp pretty easy for it... Keep in mind you can buy a good rebuild kit for it and do it yourself for $30. not for sure this is the right one but pretty close if not...
http://www.builderdepot.com/browse.ihtml?pid=1031259&step=5&prodstoreid=10745

You can buy a lifetime refurb from O'Reilly's and then swap them out everyt 3 years... Usually if you buy a refurb they are rebuilt in Mexico with cheaper parts.... The labor is good the parts are not... So i usually rebuild them myselg to save time and headaches changing them later. If you go to a 130amp you need a thicker power cable to run off to the battery for the exta current... otherwise not much point...

You're stock alt is 95amps... Have a read here: Ford Fuel Injection » 3G Install Tech

That's a good website to bookmark FYI... Good place to find EFI info too...

 

Thanks for the reply, I eneded up just going with a lifetime 95amp from oreillys and I somehow got them to take the voltage regulator back too. I charged my battery too and it would barely hold 12.1volts so I put a tester on it and it was shot. I ended up getting a 850cca Motorcraft battery which has a 3yr free replacement and 100 month prorate warranty, so I should hopefully be good for a while. Next, I think I need to get ahold of a new positive cable......the one that goes from the battery to the solenoid and from the battery to the starter. That sucker is spendy. The best price I could find for it was like $85. It'll have to wait til next month.

 

http://www.knukonceptz.com/productDe...?prodID=KFX0BK <<< go with the 1/0 cable
How-To: Big 3 Upgrade - Ford F150 Forum - Community of Ford Truck Fans << check out this write up, i know its not for our year model but it lists the supplies you need and how to do it... i did a price check and everything you need minus the posts were about 65, thats to do all the wire. beats just one wire for 85

 

Make your own. If you have solder and a small propane torch for copper work you can do it easy! You can buy custom length cable from O'Reilly's and then put the end you want on each side of the cable. Easy and cheap (just did mine for under $35. Just takes a little time. This way also allows you to put custom ends on the cables, make custom lenghts, and choose the guage you want...