1984 S (Auto). If you want the brief version, skip to the end where the ***** is>>>>>

Finally got some stuff done this weekend--the interior of the 928 is still completely bare (but, I got the Oil leak fixed on the 318is, replaced a switch on the Yamaha {still no turn signal/horn, but the broken switch is replaced}). So, I figured I'd work on the belly-up shark.

I have a replacement fuse panel--thanks to a guy (probably here--"Likars", you hang around here?) that was selling a couple of doors on ebay (Didn't get the doors, but got the window motors, and a bunch of other stuff). I spent last night using electronic cleaner to do the fuse area, etc, and swapped my relays into the new panel. Made sure all the fuses were proper, and any that looked old/suspect got replaced.

I put it into the car early this afternoon.

Then, I went to put the (proper sized) battery into the box. Had killed a bit of rust in the box, re-painted the interior. Couldn't find the damn + battery connector (I took them off to clean the wires and while I was painting, and replaced the - cable as it was a bit worn). Trip to Wal-Mart.

Back--put the connectors on the wires, hooked up the battery.

Started, ran for 5 seconds, died.

Wouldn't start again.

Got my neighbor to crank the car while I hooked an indicator light to the spark plug wire--got a light.

Can't readily get the fuel injector wire loose from the most visible one (I have an indicator light that plugs into the wire to show if it is getting current).


************************************

So, had a brilliant thought--hook my Volt Meter up to the fuel pump again--NO voltage with the key turned. I tried pulling the EFI and the Fuel Pump Relays (one at at time) and jumpering 30-87 (or 2 x 87 in the case of one). Nothing. Jumpered Upper Right to Lower Left Z-plug (in case the alarm is doing it). Nada. Tried leaving Z-plug jumpered while jumpering the EFI and Fuel Pump relays. Nada. Still won't run. No visible voltage to Fuel Pump or noise therefrom.

Took the battery out of the BMW--hooked a 10 amp fuse in line (about 3 yards from the car) hooked it up to the fuel pump--SUCCESS. Fuel Pump runs!!! Run to front of car, start it--works GREAT. Idles smooth, revs nicely. Go to back and pull spare battery off--car dies immediately.

OK, now I know what the issue is (not fuel injection--that seems to work fine).

Any ideas on how to track the issue from the Fuel Pump forward (or the other way around)? I do have a continuity tester on one of my Multi-Meters. Where is the ground point that the fuel pump uses?

You know--there is a brown?? (slightly melted insulator, hard to tell the color--not a good sign, however) wire and a green/red (I think--going from memory right now on the colors) wire going to the fuel pump. Wonder if I should start with the Brown (Ground). Run directly to the battery in the car (-) and try that next.??

Thanks!!

 

Not to hijack the thread, but I've got a similar problem that I've been working on today.

I'm getting 9.04 volts at the fuel pump (testing from + to - wire, as well as + wire to battery ground). I'm suppose I have a short in my positive wire somewhere, but does anyone know what voltage range the Bosch pumps work? Must you be getting a full 12-13 volts or will it run at even 9 volts?

Please share whatever you learn, AFARR! I'll be sure to as well.

 

I dunno, but if I cannot figure it out--I may run a fuel pump cutoff switch and hard-wire to the battery (through a fuse, of course). Not entirely sure of the source of the problem, but it is nice to hear the thing running.

I will keep an open eye for replies--be nice for both of us to get our vehicles running!!

AFARR

 

Kary, Likely you have high resistance in the line. (most likely the connectors). The pump should run with 9 volts (only will rotate slower/ and less pressure). If you can use an ohm meter (which it appears that you can)you can check by going from terminal 87 on the relay board with one of the leads and to the connector at the pump. I only have a usa WSM but shows the wire colour to be red with green stripe. There should be no or very little resistance. Using the continuity check found on most meters will beep when the connection is good. If the resistance is larger than say 1000 ohms you may have some bad connections in the line . IIRC the fuse panel is wired from the fuses to the relays to the connectors on the bottom by wires. Maybe one of these has pulled off? The fuse on the '84 is after the relay so you can check from the fuse back to the pump. on the '78 USA diagrams it is before so you must pull the relay and check there.

Hope this gives you something to check.

__________________
Rod
’84 928 – undergoing sex change operation
'83 928 - Automatic – Originally red / now black with some originality showing through
‘Got to have a beater to drive while fixing the other one. right?’
’82 928 – 5 speed – organ donor for the ‘84

 

Thanks--definitely something to go on.

AFARR

 

Do you have battery voltage at the FP fuse and relay? ... and so on down the chain: or where can you find 12v in this loop? anywhere?
Did you have no voltage at the pump using the pump ground ... or by using a clean chassis ground? Did you check continuity on the pump ground? ... should be <2 ohms. Lots of questions, but it may be that you have a poor pump ground ( ground the pump directly to the battery with a jumper and try to start up).

 

Thanks Rod - I'll be checking tonight!

 

Found my problem.

I found no resistance between terminal 87 and the fuel pump.
I then found lots of resistance between the fuse and terminal 35 of the fuel pump relay.

Tonight, I took the fuse panel off & reseated the connector to the fuse.
Tested resistance & found that all was well again.
Put the fuse/relay panel back in place.
Jumped the relay & tested voltage at the fuel pump - 8.79 volts - worse than before.
Tested resistance between the fuse and terminal 35 again - worse that before.

Damnit.

Oh well. Tomorrow night I'll have to try again & actually clean the connections on the back instead of just reseating them.

-- Man, those wires back there are knitted together tighter than a sweater.

 

DeOxit, maybe. Avaialble at Radio Shack now, I'm told. Many swear by it.

 

Still no luck--

Today, I:

Hooked the Ground directly to the battery (tested with it that way and with it unhooked). I also tried starting the car, and have a volt meter hooked up to the fuel pump (running a couple of wires to the passenger area so I can keep an eye on the voltage).

Jumpered EFI and Fuel Pump relays. No Voltage to pump (key on run or out, didn't matter).

Jumpered Upper Right to Lower Left Z plug (in case the Alarm is causing the issues). No Go. Jumpered EFI and Fuel Pump and Z-Plug at the same time. No Go.

Checked Continuity of Green/Red wire (at fuel pump) to the Fuses--for some reason I get continuity at ALL the fuses (not just the fuel pump fuse).

Tomorrow PM (time permitting), I'll raise the back end of the car and start to trace the wiring forward).

Any other thoughts?

 

I wish I was there to help, because I can't think of anything else. Sorry, man. If I come up with any ideas, I'll get them to you ASAP.

 

Thanks for the thought. At least I know the root cause--

The insulator for the Ground wire at the fuel pump is melted slightly--makes me wonder if it melted the wire insulation for the Green/Red wire somewhere out of sight.

Now, with the Fuel Pump off--I get continuity from between both poles of the pump...

Does anyone know if that is correct, OR--if someone happens to know the proper resistance of the Fuel pump--I can check that. Tomorrow, the wires come off the pump--I'll check continuity of both wires (touch the both terminal ends that attach to the fuel pump--with the key out, battery disconnected, there should NOT be any continuity--since the Relays, Ignition, etc. are all off (open circuits). If there is a short, I will get continuity--I would much appreciate it if someone can verify for me.

Thanks!!

 

Hello I'm new here on Rennlist and I have a 86 928s with some of the same problems, no signal at the injector,fuel pump dose not run, on and on, if I have some kind of a break through I will let you know what I found, thanks for posting it helps me out alot.

 

Welcome backnblack!

You've found the place to go. We'll assist you the best we can. The people here are fantastic help!

 

This is a little write up i did for P's vintage wasserpumper forum for a no start condition on 84 and older 928S's(most of which probably applies to later models, but i don't know):

For the boards pleasure:
(the following is written for the 83- 84S cars, but most of it applies to the 85 and later 32v cars, and earlier models as well i believe)

Start by locking and unlocking the d/s door lock from the outside(with the door closed). This should reset the factory alarm fuel cut-off.

Assuming that does not correct the problem, proceed to the fuze box, and check for power at BOTH ends of fuze #22(fuel pump). You should have 12v at both ends.

Assuming that's good, move to Relay XVI. Pull the relay, and check for power at Terminal 30. There should be 12v there.

Assuming power, tap the relay on the ground a few times and reinstall. Now try to restart.

Assuming car does not restart, re-pull relay XVI and use a small screwdriver and pry the little metal cover off the relay, and then plug it back in. Have a friend crank the car while you manually squeeze the relay contact closed(or contort yourself and do it unaided). It is wise to use fine grit sandpaper or whatever to clean the contact points of the relay as well before reinstallation.

It should start at that point if relay XVI is the problem.

If you have power to all those things, have someone turn the key to the run position while you lay under the p/s rear bumper(carfully of course). You should hear a 'buzzing' sound for a few secs. That will be your fuel pump. No buzz, but power through fuze #22 and relay XVI means a bad fuel pump or bad wiring somewhere after relay XVI, but before the pump itself.

If the fuel pump buzzes, and all the other stuff i listed is good, next turn the key to the on position and listen for a lot of random injector clicking under the hood. If you hear that it means your LH computer just went bye-bye.($$$$$$$) This is very rare on 84 and older cars, and i dont believe 16v Euros have this problem(mechanical fuel injection)

If it's not one of those things listed above, pull the distributer cap and crank the car over. If the cap doesnt turn.....your t-belt went(not to worry 84 and older US owners, our cars are non interference designs!). If it does, about the only things left to check are the coil for power and output, and the alarm system(of which i know almost nothing about).

There is almost a 100% chance that your problem is one of the things i listed above.

Good luck!