Fuel Pump Relays rewire

[wal280z]

20 hours ago, Jeepers92 said:

wal280z I have not had time yet to check the wires, I most certainly will be doing that Saturday when I can get out in the sunlight. Thank you. I'll let you know how that goes. 

Thanks again for the help, I'll report back on Sunday.

@Jeepers92 - a small suggestion for you - after replacing the fusible link as Captain Obvious mentioned, if that cures your issue, that's great. But, before unwrapping your harness, give it a slight twist (reference my first picture) leading from that 4-way intersection of wires about 4" towards the alternator, and about 4" up to the fusible links. Those are the two areas where the wires are spliced. No need to open Pandora's box unless you absolutely have to.... Usually, if the key is left on in the ignition, you will HEAR all sorts of relays clapping once they get a good 12V feed....

Edited January 25, 2019 by wal280z

[Jeepers92]

The new Fusible links will be here tonight and I'll put them in. I'll get back to everyone when I get this in and test it and let you know what happens. 

[Captain Obvious]

Excellent. Make sure the brass connections on the car are really really clean (600 or 800 grit emery cloth) and make sure you get the links in the proper locations.

Biggest one on the passenger fender side of the block closest to the radiator:

[Jeepers92]

Hey Everyone, I'm back. Hello Cap thanks for all your advice I've really appreciated it. 

The snow is gone and I've been able to get out and do some more work. 

I pulled out that relay from under the dash and did some testing. I did the 12v test and found that only 1 of the 2 solenoids were clicking. I opened it up and found that there is a ground wire (oddly) that goes from the one not clicking and it appears to ground to the metal casing of the relay. I replaced that wire and re soldered it. Put it back in and the car starts again and runs. 

Also we bought all new fusible links and replaced all 4. I wasn't sure that they were the problem. The links aren't particularly expensive, so we replaced all 4. 

As one more test because there was a bad wire. instead of having the fuel pump hooked up to the relay, we put a manual switch in the car just temporarily until we can replace the wires. The wires run strait to the battery and it has a 30 amp fuse. somewhere in the wire just behind the passenger seat it looses current so we'll have to find that but that's the only bad wiring we've found. 

I am going to go unravel the tape right now on the harness under the relays and see what it looks like as suggested. 

The ignition switch as I said is new, the starter and alternator are new. 

So we went out, started it up and it fired up. we ran it for 33 min with it warming up and no problems, however, we didn't turn on the lights or anything electrical. 

After that time was up and it was still running we turned on everything we can turn on, accept the radio it doesn't have one. 

Instead of the flashers we turned on a blinker. 

after it had run about 10 more minutes with everything electrical we could turn on. It died again. 

Checking the battery the voltage is down again, so we are going to replace it. Of course Autozone wants to charge it for us first to confirm that the batter is bad before replacing it so we are waiting for it to charge and we'll put it in again and see what happens. 

Any advice on what to check maybe before or after the battery is in and the process we should follow? I've compiled all the steps above people have recommended so I have them all I'm just wondering about the order you would do things in. 

 

Something I read on another forum was that alternator is a common issue and have replaced it with a Chevy alternator and have gotten past a power issue. Is that something you'd recommend. I haven't found which one they are using however. 

Some things I don't get, the alternator runs the car after it's started not the battery. If the battery is bad and it's running things like certain relays still instead of the alternator that obviously could be a draw in something that battery is running. If that's true, what is it that could cause the car to die once the battery gets low on juice. 

 

[wal280z]

Perhaps @SteveJ can offer an interpretation of what I offer...

Using the AMP setting on your DVM, measure the amperage the Alternator is putting out.... Record this measurement.

Next, find the +12v FEED to the black fusible link and measure the amperage draw at that point.  Record this measurement.

SteveJ can give you better advise on percentages, ratios and what not...

If it is significant, hate to tell  you, but you need to dig into your wiring harness for the disconnect.....

SteveJ - I know I have not detailed on 'how to', but you have given excellent direction before... (Thank you!!)

Wayne

[Jeepers92]

so the battery was bad much to the disappointment of AutoZone who didn't believe me. 

We got the new battery back and put it in and tested it, with the meter. 

With nothing on it sits at 12.26

When we start it, it drops down to 11.80 and slowly rises up to 12.01

When we turn on everything electrical, we go down to about 11.36 and it bounces up a bit to 11.46. 

So the alternator is apparently not charging. 

Just took the alternator up to be tested by AutoZone. 

We replaced the alternator not because it was bad, but because the other one was old. It looked like the original but AutoZone tested it and said it was good. 

I did wiggle around wires from the harness, the fusible links starter, etc. no change in anything. (I'll do the amp test between the fusible link in just a bit after the rain stops, I didn't want to open the case)

It seems strange to me that an Alternator that tested fine and is made for the car which is stock and doesn't have any mods of any kind and does not even have a radio, has difficulty charging. 

I'm back to wonder if it's a drain some where or maybe the alternator just isn't putting out enough current.. 

I've read a bit about some folks that have used a GM alternator or others in a 240 and a 260 but I haven't found that yet in a 280z. 

Should I even be thinking that at this point? 

Ideas? 

 

[Zed Head]

What is your idle speed?  And did you rev the engine up a little bit when you were checking for charging?

Have you checked for voltage at the T plug wires?  They both should show battery voltage with the key on and the engine off.  One senses battery voltage, the other supplies current to the windings.  Your 78 came with an internally regulated alternator.  Might be that somebody cut your L wire, the one that supplies current to the windings. 

Does the red Charge light on the voltmeter light up when you turn the key on and go off when the engine starts?  It's supposed to.

[SteveJ]

Please go to the top right of your screen where your username is. Click on it, and choose Account Settings. In the left hand column of the screen, you will see Signature. Click on that and add the year of your car to your signature. Without that bit of knowledge, I'm not sure if you're doing a bad job of throwing parts at a problem or a terrible job of throwing parts at a problem.

In your voltage testing, you do not say what RPM the car was running when you took your measurements. That makes a difference. Look at the EE section of the factory service manual for your year and read what it says about testing.

[SteveJ]

I went back to the top of the thread and saw you have a 78. Are you sure the new alternator is internally regulated? It should have been rated at 60A. If you got a 50A or 40A alternator, it probably doesn't have an internal voltage regulator. If that is the case, your voltage would read low since there is nothing to excite the field on the alternator. Page EE-20 describes how to test. Prior to testing, make sure the battery is fully charged and make sure you have a good ground on your alternator. Do a resistance test from the E terminal (ground) on the alternator to the negative battery post. It should only be about 1 ohm or less.

[Mark Maras]

 Recheck the battery voltage at idle and at 2500 - 3000 rpms.

[Jeepers92]

Thanks everyone I'll get some better details for you as soon as I can. Most likely tomorrow due to the downpour of sleet we have now. 

We did rev it up to 2500 RPM and I did check the ground on the alternator. It was just .7ohm. 

I did not test the T plug wires. I'll need to do that. 

We decided to pull it out and take it up to AutoZone and have them test it. 

They were the same ones we bought the battery from that is apparently no good. 

They are telling us that the Alternator is no good and they are ordering a new one to come in tomorrow. 

I do not recall off hand the Amps of the alternator nor if it has internal regulator, I'll call them and check. They have the paperwork on it as a return.  

I'll get details back to you prior to putting the new alternator in and get the other tests done and see how it goes. 

Anything else you think I should do let me know and I'll get it all done tomorrow. 

Steve, thanks for the suggestion on the signature line, I've fixed that now. 

Thanks. 

[Jeepers92]

From autozone the alternator is 60Amp and there is an internal voltage regulator.