12 volts and not turning over =(

[dilldb]

Hi everyone, I got a 84 King Cab z24 nissan and it's awesome but I've ran into a problem...
This morning I started my truck fine and the volt gauge read 13V but once I started driving down the highway it was reading 8-10v with the heater on and lights. While I was driving to work my CD player started skipping and turning off.
After work I started the truck fine and the volt gauge read 13v then quickly dropped to 12. Again while driving on the highway it was reading 8-10v with heater and lights.
After I got home I tried going to the store and the truck wont turn over at all! The volt gauge reads 12v lights work and everything but it just wont turn over at all.
I haven't tried jump starting it yet. The battery terminals are fine and new.

PS it's COLD here in Canada.

Also quick question...
I just ordered a weber carb and I'm curious, will I need a new fuel pump or anything the new carb?


TY! I love you all.

[MinisterofDOOM]

It sounds like an alternator problem, but it is a little weird that it still won't start with a good 12 volts from the battery. Alternator problems can be irritatingly intermittent, so that may explain why the battery seems to stay charged but after a bit of driving the problem starts to present.

I'm no 720 expert, so I'll defer to the experts for the fuel pump problem. I suspect, though, that unless your new Weber is going to be flowing a LOT more fuel, you're probably safe with the stock pump.

[dilldb]

Thanks for your input that's probably the reason for the low volts while driving... one thing I forgot to note is the last owner of the truck got the battery from pick n pull and it wasn't even the correct battery for this truck. I think the reason why it wont start at 12v is because the old battery, cold weather and since the alternator is probably bad the battery probably isn't getting a full charge(I think the truck is rated for a battery with higher amps). That's my guess.

[XavierBK]

You shouldn't need a new pump as the stock Hitachi's run on low pressure like the Webers. It has been said that the Webers are picky about their pressure so if you do have problems you'd want to fit a regulator. I think the Weber manual calls for something like 3.1 psi.

[PEZi]

I used the stock pump until it failed with my weber. Just be sure to put a fuel pressure regulator in it as the stock one can actually flow TOO MUCH pressure. As far as the battery, sounds to be alternator related to me, as well. 12V doesn't necessarily mean it has enough cranking amps to turn over... those could have been drained from the lights and heater with nothing going back into the battery.

[dilldb]

Hey thanks everyone for your help! I'm gonna get a new alternator tomorrow for 120$ =(... I can't wait(need to go to store, work, ect) to get a new one from pick n pull or online so I must get one from lordco. Anyways when I got this truck there was a ticking coming from the fuel pump so I'm thinking that I'll just get a new pump now. Do you guys think that this pump will do without a regulator for the weber I'm getting?
http://www.ebay.ca/itm/Fuel-pump-low-ps ... 390wt_1397

Again thanks for your support everyone it really helps!

[XavierBK]

It will probably work... but think about it. Without a fuel pump your truck isn't going anywhere, right? Don't cheap out on parts that are CRITICAL to your vehicle running. Do a little research and you'll find that often times the cheap fuel pumps will burn out and leave you stranded within 6 months. Spend a little more today for a quality pump instead of buying 2-3 cheap ones in the future.

[PEZi]

I still have an awesome fuel pump sitting around... problem is that it won't be to you in time. And I don't even have the time to ship anything right now.

[fastboatman29212]

A starter is the single largest consumer of battery power on any vehicle. It only works for a few seconds (while cranking the engine), but it draws a HUGE amount of current from the battery. Your voltmeter should read around 14V with the engine running and a properly functioning alternator. Use a multimeter to measure the voltage across the battery terminals and it should be just over 12 volts with the engine off and 14V with the engine on.

If you don't get those readings, then your problem could be:
1. a loose alternator belt
2. a bad alternator
3. a bad battery (but this would only be the case if you get 14V with engine running, but it still won't start the truck). The battery can be checked at your local parts store to see if it is good or not.

See the DIY thread showing how to replace the alternator here 720-alternator-replacement-thread-2wd-m ... 21512.html

[dilldb]

I just installed the new alternator and OH NO. I got my brother to come to my place with his PT cruiser to jump start me........ one of the wires connected to the positive side of the battery caught on fire! it's a small wire that I can replace I just hope nothing else melted away. I got him to take my battery and charge it in his battery charger so tomorrow I will test to see if everything still works *cross fingers*. I don't know how his PT cruiser is that deadly haha.

Oh yeah when I got the alternator I also got a fuel pressure regulator for $20. The new fuel pumps in store cost too much so I'll just have to use a regulator till I can afford a new pump(I wanna go snowboarding this year).

EDIT
After doing some research I think I actually wired the alternator incorrectly. I'll have to look at it again tomorrow when there is light. I'll let you guys know.

[XavierBK]

The small wires are your fusible links. Probably blew the one tied to the alt if you wired it wrong.