I was driving my car yesterday about half a mile down the road and noticed the voltage guage on my dash was reading right at 12v, it always runs at 14 so this was a bit of a concern, but I wasnt going far so I turned it off, and came back out about 3 hours later. Drove it home the same half mile and the voltage wasnt any higher. So this morning I get up to test it out with my digital meter and I get 12.3v off the battery and 12.5 with the car running. After a few times trying to check wires and loosen/tighten the belt I hear a loud buzzing. Looked around and finally narrowed it down to my fuel pump. Never did this before, it was quite noticable. I pulled the harness off it and hit the key again, just to make sure and the buzzing had stopped. Plugged it back in and tried to start the car and all it wanted to do was act flooded. My car is a 83 GS with the original 12a. So I guess I have a few questions:

1) could my fuel pump acting up be the cause of my low voltage reading?
2) is there some kind of relay that could be not functioning properly causing my fuel pump to act this way?
3) if it is my pump.. anyone got a spare they could send me cheap? I am trying to sell the car to move across country and really didnt want to have to put more money into it


Thanks everyone, you have all been very helpful in the past

 

Was the fuel pump making more noise than it normally does? If you have the keys turned to accessory, it will turn on even if the engines not running. You just tend to not notice it because usually the engine is cranking before you have a chance to hear it.

If it does turn out to be bad, I have a couple in good working order. PM me if you want one

 

I was having lots of carb issues earlier in the year, had plenty of chances to hear the buzzing but never have, so I think it is a new development. do you think that could also be the cause of my low voltage? or is my entire car trying to die on me because I am trying to sell it?

 

Sounds like the alt is not charging. I am not sure why your warning lights are not coming on, though. As the voltage drops, you can run into all sorts of strange behavior with ignition, fuel pump, and so on. Take the alt off and get it tested (since you can't drive the car). Most autoparts stores can do it for free. Just get a used alt if it is bad.

 

I think the alt is on its last leg, it reads about 12.5 on my meter with the car running, and slightly less on the battery with the car off, I forgot the autozone will test them for free though, thanks for reminding me

 

I drove my car for over an hour without the alternator power output wire hooked up and had no idiot light come on. The whole time I was driving it read 12-12.5 volts. After reconnecting the wire it shot right back up to the 14 range. If it tests OK, I think you should upgrade your alt wiring. Isnt going to hurt and will be cheap.

 

If you need a stock pump PM me, I'm close so it'll be cheap. You may even be able to pick it up if youre from the SE of Michigan

 

12.3 volts with no draw on a battery is no good. charge that puppy up while you wait for a new alt or you'll be shortening the life of you battery.

 

What should the battery read??? I am pretty sure that most auto batteries have 6 - 2 volt cells which equals 12 volts.

 

Putting my GM 105 amp alt in either tomorrow or Friday (my birthday no less) then I will try to tackle the fuel pump. The battery came with a year warranty in March, so I am not too concerned about shortening the life of it.

 

Happy B-day! How old?

 

Anywhere between 12V and 12.5V on the battery when the car isn't running is perfectly fine. When it gets below 11V is when you gotta worry. This is of course without any draw on the system which means NOTHING is on.

 

The big 25 *gasp*

 

I got the alt in the car, belt on, everything perfectly aligned, *crank, crank, crank, sputter, crank, crank* WTF?!?!? Can't hear the fuel pump today because the wind is blowing like crazy. Car is acting flooded. Took the cover off the air filter, tried starting fluid, *crank, crank, sputter, crank, crank. OK, that didnt work. Pulled the plugs out and they are Dripping gas. Cranked the car without them in and I swear about a gallon of gas came out of the lower holes. Looked in the carb while my girlfriend cranked the car and I didnt see gas going in, but it was sure as PITA coming out. Cranked it a few more times and the gas kept coming, left the plugs out and I am gonna try again tomorrow to see what kind of results I get.

Rx7 Says "Happy Birthday, I burned out the alt and killed the fuel pump"