dmyruski

Short version: 92 Z-28 305TPI, It will start but then stall out after 30-45 seconds or if I press the throttle. I had a battery charger hooked up and the key on when I heard a very slight Humming / ringing noise in the engine compartment. Found it was coming from the alternator. I unplugged it and she runs. Had a little hesatstion but probably needs to clean itself out. While running I plugged the alternator back in and she stalls instantly. I assume the alternator is back feeding and I think maybe messing with the fuel pump or injectors. Anyone ever have this happen or idea of what's actually happening? Is it a simple change the alternator or could there be an underlying problem.

I put a new A C Delco alternator on 3-4 years ago.

OrangeBird

iTrader: (1)

The "humming/ringing" noise in the alternator with the battery charger hooked up to the battery is a classic telltale of shorted diodes in the alternator . An alternator , as it's name implies , generates AC power , which must then be rectified into DC power by a network of diodes in order to charge your battery and play nice with all the other DC devices in your car . The shorted diode(s)* not only allow the crude DC (unfiltered with lots of "ripple") of the battery charger to ring the stator coil(s) when the car is off and your trying to charge the battery , those same shorted diodes also put an unfiltered AC artifact on to your supposed to be pure DC system when your car is running . And in your case your ECM doesn't sound like it's appreciating running on the amount of AC your alternator is putting out , hence the car running OK when you pull the plug and stop the alternator's output .


*Could be one or more , the alternator puts out "3 Phase" AC which is rectified into DC by a set of 6 Diodes , three positive going and three negative going , usually with a final "protection" diode on better built units bringing the total to 7 .

GeneralDisorder

iTrader: (1)

Unfortunately the AC Delco units are made in China now like everything else. And Powermaster is complete garbage also. Don't get burned by them like the rest of us - I'm down 2 starters and 2 alternators from those jokers. Made in USA - LOL. No they are "assembled" (probably by the blind - nice of them to employ the disabled), from CHEEEEEP Chinese imported components. My last Powermaster was "ringing" with the key off also. Both of their XS Volt alternators I've had died within months. Fortunately I run an Odyssey battery and it just took the abuse like a champ.

We get all our alternators from DC Power Engineering in CA. Check them out. Their online catalog is terrible though so you need to call them:

https://www.dcpowerinc.com/

Bonus - you can have the alt anodized any color you like. Takes about 5-6 weeks to get one though.

GD

OrangeBird

iTrader: (1)

When people take the time to make a post answering your question , a Thank You may be in order . I have a longstanding policy of never replying again to someone who can't be bothered to say Thank You when I've provided the answer they were looking for .

Good luck and good bye dmruski

dmyruski

You are 100% Correct. I truely do appreciate everyone's input. I cross posted this on another Z-28 forum, and though I put a a thank you out on both but I guess I was mistaken. So thank you all for the input. I had the Powermaster ordered with prime so I was able to make a car show this weekend, however I wrote down the information you guys provided so I can upgrade when this one craps out. So sorry again and thank you all very much.

OrangeBird

iTrader: (1)

Cool dude , I appreciate that !

The reason it bothers me when people don't say thank you is that I consider all third gen owners brothers of a sort (or sisters too , Kin if you will) . We are all we have , the rest of the world thinks we're nuts

GeneralDisorder

iTrader: (1)

The information is helpful to me also. I'm going to take this Powermaster unit I have apart and show everyone the quality of their product. Thanks!

GD

OrangeBird

iTrader: (1)

I will be interested to see your findings , I loved your 700R4 thread where you showed pics of the failed parts .

IROCZ1989

iTrader: (1)

Mechman makes them as well. They both make nice units to replace the CS130. Price isnt for the bargain buyer though.

dmyruski

Update:
Put the new alternator in Last Friday. Humming is gone but the car still won't run right. It will stay at an idol but any throttle and she dies. I need to stop by my dad's and grab my fuel pressure set but I just put in a brand new Walbro 255. Only about 20 miles on the pump. Anyone have any issues with them? Their supposed to be a good fuel pump but then again I always thought Powermaster made good alternators.

GeneralDisorder

iTrader: (1)

Walbro's are usually ok. Loud, but they only rarely fail.

GD

dmyruski

That was my impression of them. And ultimately the reason I chose it. Guess only the pressure test will tell.

GeneralDisorder

iTrader: (1)

Last time I thought I might be on a failed Walbro job it was poorly installed by the owner and the hose had popped off the pump or ruptured. Make sure you use submersible fuel line. LOL.

GD

dmyruski

Pump is good. 45 psi at Idol with the regulator unhooked. Any suggestions anyone???? Idols good for about 30 seconds then surge/dips and if at any point I give it throttle she dies. TPS, MAP both tested good.

IROCZ1989

iTrader: (1)

Bad 02?

dmyruski

I think they run in open loop untill warmup so in theory it should not affect anything untill warmed up. I may be wrong but usually with a bad O2 you just get bad fuel milage maybe small runnability issues. I would also think I should have a CEL if it we're a sensor. But I guess it can't hurt to check. Thanks.

IROCZ1989

iTrader: (1)

Did you check the iac?

dmyruski

IAC controls the idol. The symptoms would be opposite if that was the problem. It would run with the throttle but not idol. I was thinking maybe the CTS (coolant temp sensor). I know they would go bad in the TBI trucks and cause all kinds of runnability issues. Anyone see/hear of this on the TPI?

GeneralDisorder

iTrader: (1)

Check the live data. CTS is a possibility.

GD