Fuse Box question
 

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.

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

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

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?

1980 Euro 928S

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.

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?

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.

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.

Another Okie 928
 

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. :(

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

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?

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.

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?

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

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.

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?

A CIS does not have electronic injectors so no Fuel Injection relay. Since no FI relay, no three lead bridge/jumper will be used.

The comments about jumping the FP relay means to bridge the relay pin connections in the CEP; this takes the relay out of the circuit and provides direct voltage through the path previously discussed. The Pin numbers on the relay should give you the corresponding orientation to the pin socket/slot. Only need to use a two lead (male) bridge 15 or 30 to 87 if you have FP spin with 30 but not 15 you have an issue from Ig switch to CEP FP relay.

Get the Wiring/Current flow diagram for a CIS and it will be consistent for the euro and a relay map to show you the plug configuration Manuals the '79 is CIS the '80 is not. These diagrams do not show the CEP configuration...Configuration diagram Key but the plugs are not labeled...as suggested look close with good light...A-Z left to right is a general rule but it goes out of sequence at the middle where the single red leads from the jump post plug in.

Jon

I hooked a wire directly from the fuel pump fuse ( it had power ) and then to my fuel pump positive side connection. The pump didn't turn over continuously when I did this. When I intermittenly put the hot wire on it, it seems to bump over but then stopped. With continuous hot voltage, shouldn't the pump continuously run? The pump is new.

Clogged with debris?
Remove (no sparks!)
Take it away from the car, reverse terminals on a 12 v battery to attempt to clear its throat.

Actuation should be properly installed, then jumper 30 to 87 at panel (its in the WSM, too).
Running other wires up in that tight space by the pump risks spark.


Oops on injection relay, sorry, wrong 80.

The smaller diameter connector on the pump is the positive. Did you connect the lead to the wrong connector? Also, have you checked to make sure the negative lead has a good ground connection to the body?

+1 on possible clog if it does not run consistently it should just spin until no voltage...as suggested pull the FP (it is not very hard) and put 12 v to the pin and ground the other pin then reverse the leads so it goes in the opposite direction. The FP is just a motor that can be energized in either direction based upon which side gets the 12 v. When you energize the pump fuel will pump out one side so have a tub to catch the fuel. One note when you pull it...do not bend/crimp the Fuel lines.

If it was clogged replace the filter and possibly pull and clean the tank...

I believe now my new fuel pump is junk. I grounded it and put continuously current to it and it virtually does nothing.

Does anyone know what the Porsche part number is for the correct fuel pump for this K Jet 1980 928S Euro? The 1980 US version L jet fuel pump doesn't interchange with the K Jet, I don't believe.

Also, what should be the fuel pressure for the K Jet pump?

thanks everyone for your help!

Here's the one I bought for my K-Jet almost 2 years ago. Still runs strong.

Google A U T O H A U S AZ and check this part number ( 69513 )

around $200

The CIS fuel system needs more pressure/volume than an L jet pump provides. A minimum is 5.5 bar with 1100 ml/30 second volume is required. Pierburg makes a 6.5 bar pump than has worked for 5+ years on my 931. It comes with an assortment of fittings for adapting to multiple CIS pump configurations. Mine came with an external check valve, but I have heard the new ones don't, so that may require using the one from your existing pump.

If you have run your existing pump for more than a few seconds without fuel it has probably seized.

Or fried.

They can get jammed with little bits of debris.

I had a new one jam and cleaned it by switching polarity back and forth while spraying WD 40 into the inlet.
Actually I installed leads on the pump so I could do this in-situ, but it's dangerous as can-be.

If you put your ear to it, or hand on it, and energize, you can sense whether its salvageable or not by the hum. Or lack of it.


Good info on CIS pump difference and source!

Yes, the one I referenced is specifically for a 928 CIS (like mine). It has the long neck which is the check valve. Also, provides the required volume for CIS (K-Jets). No adapters or external check valves on this one.

Will this one work for my K JET? :

FUEL PUMP 80 PORSCHE 928 S 8 CYL 4.7L WALBRO GSL392: eBay Motors (item 320503217204 end time Nov-11-10 16:17:34 PST)

I called Arizona ******** and he said he didn't carry any pumps for the Euros. I then gave him the part number you said and he couldn't guarantee it was for the S Euro. I trust your knowledge and everyone else's on here implicitly so I ordered that same pump that you did. Thanks! :)

Yeah, they are good to work with. Euro or US CIS is the same volume I assume. Either way, been almost 2 years with no issues at all on my Euro. How is your internal pump?

I believe the internal pump has been removed. Is it absolutely necessary to have both running? I drained the tank - maybe I should drop it down and look inside. Any hints on the best way to drop the tank and possibly change the internal pump? I bet its a toughie to reach.

Not really hard to do. Put a jack under the tank. Remove the 2 bolts holding the strap at the bumper side. Slowly lower the tank about 4 inches or so, then you'll have ample leverage space to remove the In-tank pump. I used a large Crescent Wrench. Also, make sure you douse the threads with PB Blaster or equivalent.

FYI, I ran with only 1 pump for almost a year with no issues, but decided if Porsche put it there, it probably needs to be there. I believe it is there to prevent hydro-locking.

a few things on dropping the tank ,
first there is a hose thats connected to the main body of the tank and it passes through the chassis and connects to the fill spout area,
this hose must be disconnected,
first at the fill spout its a hose about 1 1/2 in in diameter.
Then the top tanks securing bolt at the top of the tank behind the filler cap has to be unscrewed,
remove the rubber bellows to find it.

Then the vent tube inside the fenderwell,
then the fuel return line next to the sending unit disconnected.
Once all of these are taken apart then you can lower the tank and feed the 1 1/2 vent line out from the chassis go slow so you dont damage the vent connctor on the tank body its plastic and can crack.

For your situation I would not drop the tank but instead prop the tank up then remove the 2 bolts on the rearside of the cradle let the cradle drop down enough to get a socket on the tank pump if you have one,
( this can be verified by seeing wires plugged into the base are of the fuel outlet on the tank)
If you dont see wires plugged into the base area then you dont have a inner tank pump.
If want to remove the pump or in its place a fuel tank strainer only use correct sized deep socket 19Mm IIRC .
Warning there is a strong chance you will damage the outer collar of the tank and thus the tank will leak and a new tank will need to be fitted ,
so working on this part can cause other damage.
you can remove the tank sender from the top and look inside to see inner pump/strainer.
NOTE heat the sender nut in very hot water prior to installing it this will let it be bigger and then cinch down as it cools resulting in a tighter seal

Dang! That 3 paragraph super duper explanation makes my 2 sentence answer pale in comparison. MrMerlin got all the details in his answer, go with his.

One other question about hooking up the external fuel pump:

I have 2 positive wires and 2 negative wires for the fuel pump. Why is this? They both need to be put on the positive and negative terminals? I tested both positive wires and only one had power when i jumped the fuel relay.

thanks for all the information :)

where are these wires??
If you have 2 sets of wires then you should have 2 pumps if your only running one pump the make sure the other wires are secure.