Fuse Box question

[PorscheFanatic]

I cannot seem to get power to the fuel pump ( its new ). The fuse is fine along with the relay ( I believe ). I used a tester on all the fuses and they showed power. Then after starting the car awhile, all the fuses on the board do not light up with the tester. HOWEVER, the car still turns over and the windows still go down. How could the windows go down, yet the board shows no power??

Is there a main wire that feeds the entire board power? If so, would anyone have a picture on this? Any help is greatly appreciated. The car starts right up with starting fluid.

[Mrmerlin]

pull the CE panel down and inspect the back of it for melted wires get a fuse relay chart and verify that all of the fuses and relays are in the correct positions
Fuse relay chart here 928gt.com on page 2 under tips and links.
Check the power wires from the hot post and the 14 pin connector above it for corrosion and shedding insulation

[PorscheFanatic]

If the relay is making a ticking noise, does that generally mean its bad?

[Landseer]

I've had the LH relay ( that feeds the fuel pump on an 85 ) click uncontrollably.
Root cause was a bad ground for engine electronics. Located in engine compartment.

Which car are we talking about here?

[PorscheFanatic]

1980 Euro 928S

[Landseer]

I'd do exactly what Stan suggests, pull and clean panel first. Inspect.

Then clean all car grounds.

Put it back together and try it.

Then I'd measure voltage at the panel. Both at the hot lead for the circuit power and the hot lead for the actuation power on the fuel pump relay.

Then I might jumper the relay to confirm that the circuit downstream that carries the power is working, but it usually is.

When they click for me, its usually low voltage. I've had these causes: defroster wires melted behind fuse panel, shorting intermittently the relay wires and draining power; bad grounds at engine for engine electronics which actuate some relays on some cars: and bad/failing intermittent battery ground strap, with deep debiliating corrosion covered-up by nice looking plastic shroud. Others have pointed towards ignition switch being bad.

[DPW928]

Not sure about the 80 euros but the early US and Euro CIS cars have a relay that energizes for a few seconds when the ignition is turned on, shuts off then doesn't resume until it receives a run signal from the ignition. Are you testing for power to the pump during cranking?

[JhwShark]

Originally Posted by PorscheFanatic

Is there a main wire that feeds the entire board power? If so, would anyone have a picture on this? Any help is greatly appreciated. The car starts right up with starting fluid.

On your MY there should be two red wires that run from the Jump post to the CEP (relay board); the jump post gets the direct feed from the ALT and previous to that the Starter and then the BAT. The two wires may be corroded/ing and present as hard vs. flexible at the center bottom of the CEP. This could cause voltage drop to the electronics. The are individually plugged into the CEP above and not one of the big plugs at the bottom.

As has been suggested clean all grounds and check voltage:
I have not seen you post any voltage readings at the jump post and at the FP and at the FP relay (FPR) pin socket 30 (always hot) and Pin socket 15 (switched power; when ig. switch is in Run position); what is the state of continuity for this circuit?

If a relay clicks it is usually the voltage applied to the relay that causes the small coil to energize pulling the contact to make "contact"...you then hear the relay click showing voltage is getting to the small coil...but does the voltage also exit the relay to the FP out of Pin 87 (FPR).

Something else for someone to chime in about...if the Start circuit Ballast resistor is bad would there be no voltage to the FP?? The Transistor Ignition Unit is in the Start and Run circuits as are the Ballast's...so is there spark while the starter cranks but the FP doesn't spin??

Jon

[DPW928]

Originally Posted by JhwShark

On your MY there should be two red wires that run from the Jump post to the CEP (relay board); the jump post gets the direct feed from the ALT and previous to that the Starter and then the BAT. The two wires may be corroded/ing and present as hard vs. flexible at the center bottom of the CEP. This could cause voltage drop to the electronics. The are individually plugged into the CEP above and not one of the big plugs at the bottom.

As has been suggested clean all grounds and check voltage:
I have not seen you post any voltage readings at the jump post and at the FP and at the FP relay (FPR) pin socket 30 (always hot) and Pin socket 15 (switched power; when ig. switch is in Run position); what is the state of continuity for this circuit?

If a relay clicks it is usually the voltage applied to the relay that causes the small coil to energize pulling the contact to make "contact"...you then hear the relay click showing voltage is getting to the small coil...but does the voltage also exit the relay to the FP out of Pin 87 (FPR).

Something else for someone to chime in about...if the Start circuit Ballast resistor is bad would there be no voltage to the FP?? The Transistor Ignition Unit is in the Start and Run circuits as are the Ballast's...so is there spark while the starter cranks but the FP doesn't spin??

Jon

Jon,

The start ballast resistor and coil run off the 50 circuit during cranking, but the fuel pump is triggered by the 15 circuit so a bad resistor shouldn't affect the pump operation.

[JhwShark]

Thanks Dennis! Yea the 50 Bus...Start...I should have thought through a little harder. Euro '80 CIS

P'Fanatic...also look at the contact at CEP Plug T pin 5 its voltage comes from the pin 87 FP circuit on its way to the FP when the relay is energized. So if you have good voltage at FPR pin socket: 30, 15, & 87 but not at T5 (where pin 87 lead goes) then no voltage will get to the FP...either relay is bad or the wire to T5. If voltage at T5 but not at the FP then that wire is bad/open to the FP...no voltage to FP.

[drwdds]

Pleased to know there are other 928 owners nearby....thought I was the only one in NE Oklahoma (Muskogee). DPW928...hope we can compare cars sometime.

[DPW928]

Originally Posted by drwdds

Pleased to know there are other 928 owners nearby....thought I was the only one in NE Oklahoma (Muskogee). DPW928...hope we can compare cars sometime.

Yep, we have a few of them around the Tulsa area. If you get up this way, give me a call at work 622-0017. I'm here 6 days a week.

[PorscheFanatic]

Originally Posted by JhwShark

Thanks Dennis! Yea the 50 Bus...Start...I should have thought through a little harder. Euro '80 CIS

P'Fanatic...also look at the contact at CEP Plug T pin 5 its voltage comes from the pin 87 FP circuit on its way to the FP when the relay is energized. So if you have good voltage at FPR pin socket: 30, 15, & 87 but not at T5 (where pin 87 lead goes) then no voltage will get to the FP...either relay is bad or the wire to T5. If voltage at T5 but not at the FP then that wire is bad/open to the FP...no voltage to FP.

Thanks so much for the help.

I checked and I have power at 30 and 15. Where or what color is plug T pin 5? I assume those are the plugs on the bottom row, beneath the relays? When should I have power to t5 - when I crank the car or just when my key is switched to ON?

thanks again

[PorscheFanatic]

Is the T 5 plug the fifth plug from the right hand side? Also, what should be the correct Fuel Injection ( not fuel pump ) relay Porsche number? I pulled up 1980 relay chart but it seemed to be for a US version L Jet 1980 ( but mine is a K Jet ). Should the number be 928.615.119.00 ?

The Fuel Injection relay wires go to the T2 blue plug ( second from right ) but there is no connector on this plug. Should there be a connector?

[PorscheFanatic]

With the wrong fuel injection relay, the car will not start, correct? They had a relay in there but it wasn't the 928.615.119.00

[MPDano]

Originally Posted by PorscheFanatic

With the wrong fuel injection relay, the car will not start, correct? They had a relay in there but it wasn't the 928.615.119.00

Jump the terminals.

[Landseer]

Can you post a picture of your fuse panel?'

"second from the right" and 'fifth from the right" are confusing me.

You identify the plugs by either the magic marker writing on their sides, or, by the raised embossing on the panel itself (gotta have light and get close)

Same thing with the relays. Don't be counting positions, be verifying with embossing on the panel.


Looks like it should have the relay you note. What does it have?

You can jumper the relay with a three-way jumper, BTW, for a short period to test it.

Do you know how to do that?

[PorscheFanatic]

I'm not sure how to jump the fuel injection relay. Which terminals in the relay do I connect? I'll try to take a picture of the Fuse Panel today. thanks

[DPW928]

If you want the pump to run continuously, connect the 30 and 87 terminals. If you want the pump to run with the ignition key in the ON position, connect the 15 and 87 terminals.

[Landseer]

To jump the ignition relay you must connect 30 to 87 to 87.
Will not work otherwise.
So, you need to construct a three-legged jumper wire.
I can't remember if the panel itself labels the terminals
(since you dont have the correct relay, you don't have the "map" on the side of the relay for reference).
I can help figure it out with you if you need help.





Its possible to also, separately, jumper the fuel pump relay. Go 30 to 87 on that one.



Do not leave the car with these jumpers in-place.

Also, am making the assumption that you've pulled the panel and have cleaned it and inspected the back to be certain no wire melts have occured.
Its gotta be one of the first things you do on a new acquisition, else you risk other damage, even fire.
But your signature shows 3 of these things, so why do you not know this already?