Mechanics

ASTRO WON'T START UNDER 14 VOLTS

1993 Oldsmobile Other

I have a 93 Astro 4.3 W that will not start unless the system voltage is at least 14 volts. The alternator and ignition module have just been changed. Full tune up on engine was just two months ago. Starter and battery have been checked and are okay. Timing is right on the money, all plugs and wires have been rechecked. I have to either jump it with another running vehicle or hook up a battery charger. Once running, it runs great with no surging or stalling, plenty of power and pickup. The only problem while driving is with the turn signals, they will slow down and stop the longer they are on, even though the voltage meter shows plenty of power (greater then 14 volts). The other lights and accesories work as normal. The engine will refire right away once it is shut off, but if it sits more then one hour, it will need to be jumped again. In the past this engine would fire with only 10 volts of system power, can't figure this one out. Anybody got a clue? Thanks for the suggestions. Blane

I forgot to add that the fuel system pressure is at 60 psi and holds. The fuel filter has also been replaced.
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Blane
January 28, 2006.




How old is your battery? And is it a sealed or unserviceable unit with the green eye? I had an experience similar to this with a factory GM battery. The eye was green and checking the voltage was fine however an internal wall to a cell had failed somehow and battery performance was lost. Borrow a new battery from someone. Unplug your battery for about one hour to let your computor system reset. If your problem persists, then the alternator will be the next logical step to find a break or short in your system. This will be internal, therefore replacement with a rebuilt or new one will be called for. How old is your alternator, do the wires leading to it appear chaffed/frayed?

Tiny
Kenvcr
Feb 1, 2006.
Change the battery out I had the same thing go wrong with my pickup

Tiny
Justin neitzel
Feb 1, 2006.
Don't be decieved by voltage. Amperage is just as important. Chech the amperage you will probably find it to be lower than what it should be. And if your battery only has 10 volts you probably have a bad cell in it. Replace it.

Tiny
Chevy350guy
Feb 2, 2006.
Try checking for corrosion inside the main battery terminals. Especially on a side-terminal battery they tend to get corroded beyond the post.

Soaking them in hot water for a minute or so. Drying thoroughly and then cleaning up with some emery cloth is the best way.

You'd be suprided at how much voltage drop a small amount of corrosion can cause.

Tiny
Donnels99
Feb 3, 2006.
The battery has been tested four times. The first three times it tested alright. Yesterday it failed, having only 10.3 volts after 2 load tests. I thought great, at least we found it. Ha! Hooked up the new battery, does the same thing. I have checked all the wiring and cleaned the connections to be sure they were making good contact with each other. All the hoses have been checked. The alternator is brand new. I had thought that was the original problem and had it tested. It was on the border line and had a bearing that was starting to make some noise, so I replaced it. The starter was checked and it is well within it's parameters. The coil and ignition module have also been changed. Something is drawing a large amount of power during startup and while operating. The system voltage while running is between 15 and 16 volts, a lot higher then the normal 14 that it usually is at running. I am beginning to suspect the fuel pump. The pump doesn't make any more noise then usual, and it doesn't surge, miss, or stall while running, and it does come up to pressure right away. But it just seems strange that I am getting a good hard spark and it is spinning really good, yet it won't fire without the extra voltage. I did just replace the pump about 15 months ago, but that doesn't really mean much. The thing that leads me to believe this, is that when this problem first started, I could turn on the ignition severals times to pressurize and then I would get lucky and it would fire and run. But through testing it, everything appears to be well within it's parameters with the pump. I don't know. Hate to tear that tank out and found out that isn't it.

Tiny
Blane
Feb 4, 2006.
FIXED! Yeah!

Turned out that the fuel pump was not coming up to pressure unless it had at least 14 volts. At 12 volts it would only give 48 pounds of pressure. I install a new fuel pump and turned the key and it fired right off without any help. Thanks for everyone's help and suggestions.
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Tiny
Blane
Feb 5, 2006.

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