1995 with a 3.0

Hey all, the alternator quit working (charging) in my Dad's van.

My brother took the aternator off the engine and then tried to start the van to back it out of the shop. The van would start, but then die within a second or two.

Now that the new alternator is installed it still won't run right. I have to push on the gas pedal while starting the engine and it will barely idle on it's own after it is started. It's seems a little low on engine power and the exhaust stinks real bad.

The van ran fine when we pulled it into the shop. I checked for loose/disconnected wires and vacuum lines near the alternator and couldn't find any.



.

 

Ignition isn't getting enough power. Check the battery...I'm betting it's bad.


The problem for you may be that bad alts can kill good batteries...and bad batteries can kill good alts... (trust me I just did this...multiple times) So alt dies...battery runs dead causing the truck to die. You put on a new alt and try and restart it. Low battery kills new alt. You get a new battery, truck runs great for a while, but alt is dead, so the batt runs down and dies again, etc. etc.

Check the voltage on the batt. I'm betting it's quite dead.

EDIT: and yes, and engine will happily run without an alt. Technically...as long as it has some sort of way to provide fuel, air, and ignition, plus somewhere to send exhaust, once you get it's running it's quite self-sustaining. The ignition (and fuel pump in a fuel injected car) are the only things requiring electrical power. For example, the airplanes I fly use magneto ignitions, which generate their own electrical power, and mechanical fuel pumps combined with gravity. Once the engine is started, I can flip the master switch and alternator switch off and fly around all day long with no problems. Different from a car, as I noted, but you get the idea.

 

I just went out and checked the voltage and it is 12.32 volts at the battery with the engine off.

 

Four Sixty, Ranger Pilot has the right idea. Yes, you have 12 volts plus right now, BUT apparently you have a discharge or something hanging up somewhere else. What might have caused the bad alternator to begin with might not have been even the batteries fault at all. Sometimes things elsewhere in the charging system can be bad. You just might be having a starter going bad. If the bindex binds up (that is the small gear that extends out to catch the teeth of the fly wheel and then retracts back into the starter cavity once start up has occured) it will creat a discharge which will rob the current needed to start the van. Once this happens the whole system is cheated out of the 12 volts. The weaker item will suffer. First it was your alt. and now like ranger pilot said your battery is going. You have 12 volts plus right now-but-once you start the van the TRUE test is there. Go to Auto Zone and they can put a test of your entire system with it running.---Good Luck Boz

 

Are you getting any codes? I would start there before replacing anything else (besides the battery, also been there, when an alt goes, replace the battery at the same time, otherwise you hit a viscious cycle.)

 

The quation is like silly one "can a plane fly without propeller?"

Yes. Engine runs without alternator and with fully charged battery it runs for about 2 hours, but light must be off, stereo off too, and no blower.

 

I'm right there with the other guys. Get it up to a parts place and have them run the full electrical test (and if the guy seems like an idiot, let another place do it too).

Just before I did the 302 swap, the Ranger had this fun. It'd start around 12V, but slowly wind down after running. Let it sit overnight, it'd be okay the next day. But start it up, and down it went. I did that "vicious cycle" of batt/alt replacement before I wised up and did both at the same time.

 

From your description about poor/no idle and exhaust changes, I would still bet something is not connected properly. Check the connection to the Mass Air Flow (MAF) sensor on the air intake tube.

 

EEC computer requires correct battery voltage & charging conditions.

1) Check the battery for charge in each cell with a Hydrometer. Even 1 dead cell makes the battery no good ! A fully charged battery should give 12.7-12.8V. However the Hydrometer gives a better check since it measures the specific gravity of the electrolyte (acid). You can inspect each cell individually which is not easily achieved when doing voltage checks.

2) Check out the voltage across the battery with the engine running. It should read 14-15VDC not more, not less. This with normal engine load, (not with the rear defroster on! or a 500 watt amplifier playing). If you get less than 14v, you could have a defective voltage regulator/rectifier diodes.

If these tests are both good it's 90% certain that your battery/ charging system are good.

Much of the ECU uses reference voltages to run the sensors & actuation devices. If the system voltages are wrong the engine management will not function correctly.

Battery voltage especially affects injector pulse times (offset), which could explain you stomping the gas pedal to get started. So although an engine theoretically can run without an alternator , this is only as long as battery voltage is sustained above about 12v. Below that it's all downhill & I'd suspect a few hours is all you could expect even from a pretty good battery.

Good luck,
Aeroman.

 

Let me disagree. The average ECU works with minimum 6-8V voltage supply, but saves Low Voltage supply code.

But old TFI may not work when woltage is lower 10V, but engine starts, becouse there is one more voltage supply pin on TFI connected to starter relay and when starter cranck engine TFI works and when starter is off and no alternator engine stalls.

I had bad TFI and old battery it was difficult to start engine. Starter crancked engine, it fiered, but stalled in a second when starter is off. I had to press gas pedal to make engine reve up on start.

 

> 12.32 volts at the battery

Battery should be 12.60 volts at rest. Either the battery is not charged or it has a problem.

 

So what happens if we recharge the old battery to full before install a new alternator? Would it still kill the new alt to?
Thank you,
Fordboy49

 

> So what happens if we recharge the old battery to full before install a new alternator? Would it still kill the new alt to?

That should work. But make sure that the battery is fully functional. When you leave a battery dead for too long, some of its weaker cells can short out. This happens a lot to old batteries that are not tended to. At that point, no amount of charging will bring it back, and it can put a strain on the alternator trying to charge it.

 

A bad battery can definately create problems in the charging circuit. However a flat battery thats otherwise good should not harm the charging system.

 

As long as the battery is recharged to a reasonable level, the alt can handle it just fine.

If you have a digital charger to charge the battery, the "normal" level to charge it to is 77%, after that it's more than capable of safely running in a vehicle without harming the alt or the electrical system.