72 510 wagon. No Power

[GoonLuv]

I'm stumped and am hoping the Ratsun community can help. I have a 72 510 wagon that I rewired 5 years ago with an American Autowire Power Plus 20 510008. Up until today things have been great. For reasons that am seriously questioning at this point I decided to install an electric fuel pump. I have dual Weber DCOE 40's so I purchased the pump I saw recommended the most, a Carter P4070 and hooked it up the the fuel pump circuit that was part of the Power Plus 20. At this point things were still fine. I powered on the pump by switching the ignition to the on position. The pump came on and the system pressurized. I ended up cycling the pump several times because of fuel leaks. Once I got everything tight and no more fuel leaks I tried to start it. This is when things went wrong. The starter clunked once like the battery was dead. I figured I had drained it while testing. I hooked up my battery jumper and tried the key.... Nothig. Not even a clunk. No lights, no gauges, no blinkers, no break lights, nothing. And this is where I am stumped.

 

The only thing that has changed was adding the fuel pump.

 

Things I have tried.

Checked the fuseable link. its fine

Bypassed the fuseable ink still nothing

Checked the battery 12.48v

Checked for power at the starter. 12.48v

Checked for power at the fuse box on one of the unused circuits like cigarette lighter and clock. Both of which should be hot even with the key off. 12.48v

Checked all fuses in the fusebox and all are good.

Bypassed the main power to the fusebox by running a wire directly to it from the battery. 12.48v and no change. Everything is still dead.

 

I am out of ideas at this point. I have power to the fuse box but no power coming out. Things that should work regardless of the key position like break lights are dead.

Hopefully one of you wise Ratsunites can help.

[datzenmike]

Clean and tighten the battery posts and clamps. I've had poor connection here before and when the starter connects the sudden high current will break the weak connection. There's enough for a digital volt meter to read but not nearly enough to power anything else. Best to check this first as it easier to do and eliminate first.

 

 

 

Well about half the fuses are hot at all times like the brake lights, horn, headlights, clock etc. The remaining fuses are turned on by the ignition switch. Heater fan, wipers, gauges, ignition coil, start signal etc. If none of these are working then no power is being sent to the fuse box from the ignition switch.

 

Go to the ignition switch and pull the plug off and plug back in. Maybe the contacts are dirty or the plug is loose and re-connecting will fix this.

 

Still nothing?

 

Check for battery on the White/Red stripe. This is the power wire from the fusible link.

 

Likely it's OK so....

 

Plug the connector into the ignition switch.

 

Check for power on the Blue/Black stripe wire. This sends power to the fuses in the fuse box when ignition is in On or Accessory position.

 

Black/Blue is hot in the Start position but as there is no start or accessories it has to be the ignition switch.

[Crashtd420]

Dont forget about the ground wires...

I had a bad ground do something similar..... 

[datzenmike]

Absolutely! Current flow is the same anywhere in an electrical circuit. Ground is every much as important as the positive connection. The negative ground is a bolt on the head just behind the mechanical fuel pump. There should also be a separate ground wire to the body, usually to the bolt holding the voltage regulator, but after so many years the negative cable may have been replaced with one that doesn't have this. Easy enough to make one from 10- 12 gauge wire. I connected from the engine bracket bolt on the block to the engine rubber mount bolt on the frame.

[GoonLuv]

18 hours ago, datzenmike said:

Clean and tighten the battery posts and clamps. I've had poor connection here before and when the starter connects the sudden high current will break the weak connection. There's enough for a digital volt meter to read but not nearly enough to power anything else. Best to check this first as it easier to do and eliminate first.

Done. Battery posts were cleaned and tightened and everything looks secure. I get the same 12 volts at the battery, starter, and fuse box.

 

 

Well about half the fuses are hot at all times like the brake lights, horn, headlights, clock etc. The remaining fuses are turned on by the ignition switch. Heater fan, wipers, gauges, ignition coil, start signal etc. If none of these are working then no power is being sent to the fuse box from the ignition switch.

Tested for power at the fuse box using one of the always hot locations, clock I believe. Got 12 volts

 

Go to the ignition switch and pull the plug off and plug back in. Maybe the contacts are dirty or the plug is loose and re-connecting will fix this.

Pulled the connector off the ignition switch and everything looked fine. Tried connecting power to start using a jumper cable and got nothing.

 

Still nothing?

Will check these this weekend.

Check for battery on the White/Red stripe. This is the power wire from the fusible link.

 

Likely it's OK so....

 

Plug the connector into the ignition switch.

 

Check for power on the Blue/Black stripe wire. This sends power to the fuses in the fuse box when ignition is in On or Accessory position.

 

Black/Blue is hot in the Start position but as there is no start or accessories it has to be the ignition switch.

Thanks for the reply Mike. Some very good info. Couple things I will check this weekend. We did try running power direclty from the battery to the fuse boxes main feed and still get nothing. The fuse box is powered but nothing works regardless of the key position. Not even break lights.

 

 

5 hours ago, datzenmike said:

Absolutely! Current flow is the same anywhere in an electrical circuit. Ground is every much as important as the positive connection. The negative ground is a bolt on the head just behind the mechanical fuel pump. There should also be a separate ground wire to the body, usually to the bolt holding the voltage regulator, but after so many years the negative cable may have been replaced with one that doesn't have this. Easy enough to make one from 10- 12 gauge wire. I connected from the engine bracket bolt on the block to the engine rubber mount bolt on the frame.

6 hours ago, Crashtd420 said:

Dont forget about the ground wires...

I had a bad ground do something similar..... 

I will definitely be checking grounds. Main battery ground connect to the lug on the head. Then there is a ground to body at the back of the engine using one of the valve cover bolts. There is a third ground that goes from the starter to the inner fender. This one looks suspect to me. There is some rust around the connection where the bolt goes through the inner fender. I will be replacing both the ground from the valve cover and the starter with new ones this weekend.

 

Thanks everyone for your help. This was a very frustrating day to say the least. Is it really possible that the grounds could be causing this? Things like the tail lights and blinkers have their own grounds to the body.

[datzenmike]

Well everything other than the engine has to have a path to the negative side of the battery. They may have power but if no connection to battery ground, there is no flow. 

 

 The starter should click as it's grounded to the block. Perhaps the ground at the head. If bad then it won't be grounding from the valve cover to the body either.

[Icehouse]

20 hours ago, GoonLuv said:

 

Bypassed the main power to the fusebox by running a wire directly to it from the battery. 12.48v and no change. Everything is still dead.

 

 

Did the added power lead test at 12V when it was jumpered to the fuse box?  Can you see the back of the fuse box to see how all the connections work? 

 

[GoonLuv]

56 minutes ago, Icehouse said:

 

Did the added power lead test at 12V when it was jumpered to the fuse box?  Can you see the back of the fuse box to see how all the connections work? 

 

Yes when we jumped directly to the fuse box from the battery we got 12v at the fuse box. I did look at the back and everything looks fine there.

[GoonLuv]

I think you guys are on the right track with the ground. if the ground from the engine to the body and starter to body are bad then there is no path for all the other grounds to reach the battery.

[GoonLuv]

Cleaned all engine bay grounds.

Replaced main battery ground with new one and connected to block instead of head. Added new ground directly from battery to body.

Still no change. No power to anything. Fuse box is still showing 12v. Not even the volt meter in the dash is working.

[GoonLuv]

Retested the voltage at fuse box main power lead and was only getting 7v.
Bypassed the fuseable link and ran power directly to fuse box from the battery. Now getting 12v.

Break lights and headlights have started working. So there probably was a ground issue.
Still no dash lights or gauges and nothing happens when turning the key to on or start.

I want to replace the fuseable link with a breaker style fuse. What amperage should I get?

[datzenmike]

What color is the fusible link???

 

 

Do not use higher than what you need. Fusible links will sustain a higher than rated current but only for a few seconds. A regular fuse blows instantly so if going that route keep several replacements in the car.

[GoonLuv]

The fuseable link is not Nissan so I’m not sure if the color codes match. It is a brown almost black wire though. The writing on it says 2.0 30mm fuseable link.

[datzenmike]

Here's a better one. That one has obviously been changed before so unknown if the correct rating was used.  The fusible link only has to protect the wire from the starter to the fuse box. Usually a fusible link is rated for a wire 4 gauge sizes smaller that the one it protects to assure that the fuse burns and not the wire. I would guess the wire the fusible link in connected to is 10 or maybe 12 gauge???? then a 14 or 16 gauge protection is warranted. 14 gauge is 32 amps so a 30 should be safe.

 

If anyone knows the 510 fusible link rating say so. I found a reference of 200 amps!!!! the wire would obviously burn up first. 200 amps is the starter cable.

[GoonLuv]

Got her running!!!  I ended up using a 120amp circuit breaker in place of the fuseable link. Couldn’t find anything else at the local auto parts store. I’ll probably end up moving that to the main power feed to the alternator and ordering a 60amp maxi fuse to put in place of the fuseable link. That plus the ground wires was the solution. Thanks For your help guys!!