73 Gt- Alternator

[OPELFIEND]

Found out the alternator needs to be replaced on my newly aquired 73 GT. Posted a few days ago about the car losing power after running fine for 100 miles. First impression was that this was a fuel issue. Replies to the post stated that it was probably the fuel sock or a venting problem. Question is this: Being that the car has an electric fuel pump, would a bad alternator cause the car to lose power, re-start and idle fine, but stop running after a few miles? Know for sure the alternator has to be replaced, but not if that is the whole problem. Battery is brand new, but did eventually wear down after starting numerous times. Checked out the fuel pressure, all seems ok. Any feedback would be much appreciated.

[namba209 (R.I.P.)]

Not having a fully charged battery, or one that is not being charged after driving a fair amount, could have an impact on an electric fuel pump. But I would think the car could not be started after the engine dies, if that is the only reason for the engine to die. Best bet would be to change the alternator, preferably to a GM "one wire" type and see if that cures the problem. You can run a search for the alternator mod, it's been done by quite a few members. HTH.

[tekenaar]

Found out the alternator needs to be replaced on my newly aquired 73 GT. Posted a few days ago about the car losing power after running fine for 100 miles. First impression was that this was a fuel issue. Replies to the post stated that it was probably the fuel sock or a venting problem. Question is this: Being that the car has an electric fuel pump, would a bad alternator cause the car to lose power, re-start and idle fine, but stop running after a few miles? Know for sure the alternator has to be replaced, but not if that is the whole problem. Battery is brand new, but did eventually wear down after starting numerous times. Checked out the fuel pressure, all seems ok. Any feedback would be much appreciated.

Two separate problems . . . original "fuel" problem has nothing to do with this one, i.e. just because you have "charging problem", e-pump is fine as long as battery voltage is there. You still definitely have problem with gas source, i.e. between tank and e-pump . . . separate issue!

About your "charging" problem, are you certain it's not just dirty battery posts/terminals (most common problem), an ungrounded alternator (below and second most common problem) or your regulator (third most common problem)?!!

[OPELFIEND]

Battery and voltage regulator are new. Terminals aren't dirty. Had the alternator checked out professionally, and was told it needed to be replaced. Have one on the way from OGTS.

I was hoping there wasn't two separate problems. Thought that maybe the car re-started d/t the battery being in good shape, and that after driving there just wasn't enough power to drive the fuel pump or something. The thing is, all of the fuel system, including the tank, was replaced in May 2006. And, it idles fine. I did put gas in it, but I also put the same gas in another vehicle with no problem. The guy told me he had added fuel stabilizer as well, because he didn't drive it much. What a hassle.

[tekenaar]

. . . still begs the question . . . do you have alternator ground wire in place or not?? Without it, stock alternator is isolated by rubber in mounts and, therefore, ungrounded!! . . . no ground, no complete circuit. Another Opel quirk!! Sure hope your "professional" didn't test it "in car"!!

[OPELFIEND]

As far as I know, the alternator was tested in the car. I don't understand. If the thing wasn't grounded, would it run at all? There haven't been any previous problems with this. The man working on it seems to know what he is doing. I don't know. Guess I'll just have to see. Man, this is frustrating.

[tekenaar]

As far as I know, the alternator was tested in the car. I don't understand. If the thing wasn't grounded, would it run at all? There haven't been any previous problems with this. The man working on it seems to know what he is doing. I don't know. Guess I'll just have to see. Man, this is frustrating.

Without a ground, alternator just won't charge! Nothing to do with being able to start/run car . . . until battery runs down from "not charging".

Quick test . . . turn ignition key on, don't start engine yet . . . does ammeter "idiot light" come on? If "NO", that's your "charging" problem . . . alternator will not go into "charge" mode without this light in circuit!

Next test . . . if "idiot light" is "ON" with ignition key on, start engine and see that it goes off. If it does, charging system OK as long as ammeter is "centered" or plus.

[GTJIM]

Sounds like the Previous Owner has a few things to answer for!

It sounds suspicious that the car has a new battery and a new voltage regulator - almost like there have been issues with battery charging.
Do check that the ground wire Otto has mentioned is there and connects the case of the alternator to the cylinder block - NOTE: this wire DOES NOT connect to any of the terminals on the alternator ... it just goes from the outer case to the motor. Often this ground wire (and the one from the block to the chassis on the passenger side!) is left off when the motor is replaced "because it is all oily and dirty" - but these wires are necessary to let the electricity get from the alternator to the battery ... so it will be recharged.

I still think you have a fuel supply issue too - either a blocked fuel line or the vent lines to the tank are blocked.

Hey! These things are Opel "features" - which this site is all about fixing.
Just think - If you were not suffering these frustrations, what would you post on this Opel friendly site?

[jlthunder]

One more suggestion. If the 3 wires from the alt. to the regulator are original, replace them. This can also cause problems with the charging circuit. If you amp meter is in the (-) side when you put your parking lights on, you are not charging.

Check the voltage on the battery before you start the car. It should be around 12 volts. Start the car, take it up to about 2000 rpm for a moment. Bring it back down to idle and recheck the battery. It should be 13-14.5 volts. If there is no change, then you are not charging and start chasing the items mentioned in the thread.

HTH

Jeff

[OPELFIEND]

Thanks gentlemen for your input on this. The idiot light comes on and goes off as it is supposed to. The thing was in the + side when running, with all of the lights, blower and everything on. As of the moment, I'm not sure about the ground wire. The previous owner states he never had an issue with the car starting, and I am inclined to believe him. Maybe he's BS'ing me, I don't know. I doubt he has been running around without the alternator charging for any length of time. The work that has been done on this car appears to me as if it were done in a professional manner. The previous owner had someone knowledgeable work on it. I talked with the mechanic, he told me all about the car, good and bad. The battery and voltage regulator were replaced 11/06. It has the orginal engine. Your right GTJIM; without these types of issues, I would have nothing to post about.

Thanks to everyone for their help. When I get this thing figured out, I will post my experience. I'm afraid I have a lot to learn!

[baronbors]

Is it possible that when the voltage drops on the battery that the fuel pump would stop putting out enough volume to keep the car running? JMTCW

[OPELFIEND]

That's what I was thinking. Hopefully, a new alternator will take care of this.

[wrangler]

I noticed in your post that you said the terminals were not dirty, but did you actually check and clean the ground strap from the engine to the frame? If there is rust built up where the strap bolts onto the frame you won't get a good circuit. I once bought a Fiat in Germany for $50 because it did not run and the problem turned out to be a frayed ground strap!
Also, when you swap out your alternator, you might want to take it to an auto store and have it bench tested to ensure that it truely was faulty.

[tekenaar]

Sounds like . . . there have been issues with battery charging.
Do check that the ground wire Otto has mentioned is there and connects the case of the alternator to the cylinder block - NOTE: this wire DOES NOT connect to any of the terminals on the alternator ... it just goes from the outer case to the motor. . . .

I still think you have a fuel supply issue too - either a blocked fuel line or the vent lines to the tank are blocked.

Hey! These things are Opel "features" - which this site is all about fixing.
Just think - If you were not suffering these frustrations, what would you post on this Opel friendly site?

This might help . . . specifically the brown ground wire near the RFI capacitor.

[jlthunder]

This might help . . . specifically the brown ground wire near the RFI capacitor.

Just a note, Not all Opels still have the RFI Capacitor installed.

[opelwasp]

Why not just swap the old one out for a GM one wire. Much less of a headache and really adds more juice to the whole system. Say goodbye to voltage regulator and hello to bright lights heater fans and wipers that actually have 2 speeds, not slow and slow.

[tekenaar]

Just a note, not all Opels still have the RFI Capacitor installed.

True . . . as a matter of fact and even though all the Opel FSM radio installation instructions show RFI capacitor installation, the only RFI cap I've ever actually seen mounted on an Opel alternator or generator is not even in a car but one on Rodney's parts shelf in Leonard!

The one shown in my pic was installed by me only after I brought my Kadett back to Texas from Seattle.

[namba209 (R.I.P.)]

The original RFI capacitor I had on Willit? was a little black box about 1" X 2" with a tab on it that had a hole for a bolt that held it to the alternator housing and the pigtail that attached to the grounding bolt. I finally had to take it off after years of heat and age got to the wire and it fell off the box.

[guyopel]

I have the 105 amp. G.M. alt. installed and it works great and cleans up the eng. area ( no voltage regulator )
Alt. grounds through the mount bracket ( chevy. ) and is smaller unit than the 61 amp.
I hope you get your car back on the road and enjoy it. It's a pain when you can't depend on your car . Good luck!
John

[2 Fast 4 U]

About your "charging" problem, are you certain it's not just dirty battery posts/terminals (most common problem), an ungrounded alternator (below and second most common problem) or your regulator (third most common problem)?!!

This is why I made a new ground wire [6 mm² AWG ??] from the altenator to the ground wire that is bolted to the engine for the start motor, that comes from the battery negative pole.
Don't know the AWG rating for 6 mm², Ill look it up tomorrow at work, and post a convertion list Metric to AWG