1996 Cadillac De Ville with 12 gallons of old fuel in tank

Maintenance/Repairs
21

You really need to take this car to a real mechanic.

22

No, fuel pumps make a buzzing/humming noise and that is normal. It might be more apparent when the car isnā€™t running. You had enough current to run the pump but not start the car. The pump was running to prime the system for operation but it wouldnā€™t start.

This doesnā€™t mean the fuel pump is bad or going bad.

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23

The humming noise was after it was jumped and it was running(briefly). I noise only happened while the car was running.

24

Right now both of my cars the 2002 and the 1996 had to be towed. It this point I am trying to figure out which one would be the easiest and cheapest to get running. Neither car is worth putting a fortune into. The dealership will not touch the 1996, too old. They cost a lot anyhow. I am going to talk to a mechanic that has helped me before. I just am not sure which car to focus on first. I need transportation ASAP.

25

I looked at the posts but I need to disconnect them to inspect them.

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1996 Cadillac battery posts #2.jpg648Ɨ1080 85.1 KB

See how short they are, especially the negative one? And there is not a lot of space in there for jumper cables. I will have to try to disconnect them and inspect them tomorrow. It is dark and cold out now. Thank you.

26

I would not spend anything on either one of these vehicles . Take what you can get and look for something more efficient .

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27

The humming noise from the rear might have been the fuel pump struggling to pump the gas with a low voltage power supply input. Suggest to first fix the battery and alternator problems before worrying too much about the noise. Running DC motors (fuel pump, starter motor, etc) with low voltage like that can damage them, so donā€™t defer on addressing the battery/alternator issue.

Thereā€™s a quick test a diyā€™er can do to check the alternator and battery basic operation. Only requires an inexpensive digital volt meter. Before the first start of the day the battery posts should measure about 12.6 volts. Immediately after starting the engine they should measure 13.5-15.15 volts.

If I had a car with 18 month old gas, Iā€™d drain as much of it out as I could, replace the fuel filter, then refill w/fresh, and cross my fingers. Iā€™d replace the fuel filter again after about 500 miles.

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28

Thank you for the advice. I have been telling myself well, the 2002 only has maybe 30,000 miles on the engine. The vehicle has 123,000. I have had a lot of problems with it over the years. The 1996 sat a long time due to a dead battery and the air conditioner not working. That I believe is a leak somewhere. Anyhow, besides that, the 1996 has never given me many problem. I think it has a much smoother ride than the 2002. I am concerned that if I buy a different used car I am buying someone elseā€™s problem. I also wonder if I would get ripped off.

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29

That backseat noise happened another time when I had it jumped after it sat. I got it started and then I did not have that noise after it ran a while. Then a few weeks? later it would not start. That was when it sat there ayear and a half until now when I got a new battery. When the guy jumped it his jump box said 7 volts. He said it was the alternator.

30

Does the car have air shocks - that would include an air pump that runs if thereā€™s a leak? It might be running with the engine off, eventually draining the battery so much that the starter motor canā€™t run.

A bad alternator will keep the battery from maintaining a charge, but even a good alternator canā€™t be counted on to charge a badly discharged battery.

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31

The alternator is possibly the cause, but could be something else. Further testing required.

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32

Thank you I do not believe so. I will have to look tomorrow.

33

Couple of things-

At 7 volts, the battery is beyond discharged. It may be damaged. I wouldnā€™t use the alternator to charge it, you could damage the alternator if it isnā€™t already compromised. Battery should be trickle charged by external charger and then test battery capacity. Then check alternator with known good battery.

Those posts look goofy. The negative looks almost correct depth, the positive is sticking out way further than normal. Those post extensions are not like oem but something isnā€™t right about that install. Iā€™d remove and check both. Could have plastic shroud pinched or something preventing good connectionā€¦

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34

So I should take the battery out and charge it. Or get a different one. You think the negative post is okay? It is too short for a jumper cable, The positive one is not so great. When I have tried to jump it with my Stanley FATMAX I have trouble even getting the positive to stay on good. The negative I ground to the car not the post. I will recheck the set up. After I have a good battery in the car what is the best way to check the alternator? Not sure the FATMAX is reliable. Thank you.

35

You can recharge the battery in the car or out of the car, you shouldnā€™t need to replace the battery.

The negative battery bolt is short because it is not intended to be a jump start connection, use an engine bracket for the negative cable clamp. After you repair the charging system problem you wonā€™t need to jump start the car so donā€™t waste time changing the battery posts for easier jump starting.

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36

That is what I do. The guy that jumped my car used my negative post somehow. Thank you.

37

Got the car started with a jump. Disconnected the battery cable and it died. So it looks like the alternator is bad. Apparently you can remove the alternator through an access panel without having to remove the radiator and other things. Has anyone done this? Any suggestions?

38

Maybe I missed something but why are you replacing the alternator? The battery at 7 volts would not take a charge and is likely shot. Change the battery. You canā€™t run a car with the negative cable disconnected. Thatā€™s why it died and donā€™t do that or itā€™ll damage other stuff.

2 Likes
39

I view this as . . . the engine stopped running when op disconnected the booster cable(s)

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40

I got the car started with a jump. Ran it a few minutes, then disconnected the battery cable. So disconnecting the cable is not a test to see if the alternator is dead? How do I test to see if it is the alternator? The person that tried to jump the car before said it showed 7 volts. They were unable to jump it and get it started. So at that time they said is was the alternator. If the new battery is shot how did the car start when I got it jumped recently? Thank you.