illldeca

well i just bought a 1987 300zx its from california and pretty rust free im in new york. Any way it needed/needs some work the cat was plugged so i punched that out. One of the vacum advance lines was unhooked i got that hooked up. Now the alternator isnt charging the batterys but it seems to run good. on the dash the battery gauge is reading that the alternator is putting out 14.5 volts or so. But when you unhook the ground from the battery it shuts off and as it runs the battery just gets lower. It seems to run great with a charged battery when its low it will run out and just stall donno. Im thinking directly test the alt with A volt meter. Any sugestions Are there any resistors fuzes that can go bad and cause the alternator to not charge the battery? thanks

omniserv

I have a 87 as well and if the battery cable is removed on mine it will die too. I'm not 100% sure but I think the alternator needs a complete circuit to sense the charge needed. Removing the battery will open the circuit causing the charge to drop to zero.

I'd have your battery checked with a load meter or take it to autozone and have them test it. If you have 14.5 volts it has to be coming from the alternator. Unless that's just the high voltage you have immediately after removing a charger from it.

A quick test of the alternator is to start the car and turn on your headlights. Watch the voltage gauge, if it stays fairly steady than it has to be putting out a charge.

AZ-ZBum

Number 1. Do not ever disconnect the battery while the car is running. It's very easy to blow up your ECU that way. DUMB DUMB DUMB.

Number 2. Go to the local auto parts store. Most will test your charging system for free.

omniserv

I only know that the car will die if the battery cable is unplugged because one time I had it just loosely sitting on the post. My 16yo son had put the battery in and forgot to tighten it.

I started the car and as soon as I turned the head lights on everything shut off.

illldeca

well i donno i tightened the battery im using a voltemeter its a good battery 13 volts the car has alot of trouble starting until it warms up from trying to start it fires every time and stalls. It seems to have alot of back pressure, Its not making any valve lash or nocks, im thinking its eather a clogged egr or maybe bad injectors, I dont smell fuel under the hood at all though. Steam back fires from the intake sometimes. When it does finally start and idle its at like 1,200-2200 rpm studder. Also one of the lines thats by the vacuum advance by the firewall to the right of the battery keeps popping off of a vacuum tree. Im confused about this car im gonna do some testing on the alternator today, and possibly get another one if its bad thanks for the help guys

illldeca

well the battery doesnt seem like its not charging its at like 11.75-73 im going to get a new alternator. It still seems to be very hard starting i put new gas in it and blaster fuel injector cleaner. I think maybe its the timing donno, It seems to run fine and idle when its warmed up, but theres studder till you get to about 2500 rpm when on the gas in drive or any of the gears. It really doesnt run unless you really start it alot of times to warm it up. The car sat for 8-13 months in a driveway. There seems to be no studder when you press on the gas when its in park just revs to 6k fine donno. I opened it up at about 75 and it seemed fine rides good. So far i Have changed the battery, battery terminals nocked out the plugged up cat, fixed the vacuum lines. Oh an the line that goes to the ac compressor seems to be freezing i think ill delete it do you guys know the belt size?

omniserv

you might check the timing? also download the FSM and run all the test on the sensors. have you checked the ECU for any codes??

illldeca

no i havent checked the timing or codes im useta obd2 cars. Ill check the timing tonight though im changing out the alternator i got to taking it off seems like a pain in the *** a screw fell out of the casing...

illldeca

well changed the alternator drove it around for a while its not charging the battery, Is there a resistor from the alt to the battery can i bypass it? or change it out thanks for the help guys.

hoov100

check your fuses. The alternator gets electricity from the ignition in order energize the alternator. Otherwise it won't charge.

illldeca

the interior fuzes? alright ill change them out

illldeca

well i checked all the fuzes and found one blown fuze for the radio. I noticed theres a box that looks like it could have fuzes in it next to the battery it has like 7 fuzeable links in it is that supose to be that way?

illldeca

well i did some reading and its a three wire alternator with an extra ground can i piggy back the wires from it to the positive onto the battery. Theres some kinda short in the wiring one of the positives run from the alternator to the starter then to the battery. The extra ground and other wires should run to the battery donno where ealse they go The voltage regulator is inside the alternator so i dont think this should be a problem

illldeca

well i fixed the charging problem it was the fuzible link for the battery i crimped it togethor and its charging now. Can i get one at advance auto or,something are they hard to find do i need to solder it?

illldeca

well there was some stuff from the iat clogged in the tube. after the air intake they put in. I think i need a new iat. It was running like crap until i bypassed the vacuum hoses after the iat on the air intake. What do those do i assume there something for the pollutions is it gonna hurt the gasmileage of the car? it runs great now.