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My apologies for making my first post a cry for help! Sorry.

Some time ago (07-30-2002 15:38 to be precise) Iacast posted a problem he was
Having with his fuel pump, I quote: -

“Should the fuel pump always be running? Is that normal? Should it stop when it gets to its proper pressure or level. For instant, when I turn the ignition key forward prior to turning the engine on, the fuel pump turns on but never stops. It will continue running (pumping) as if it was connected straight to the battery”.

Unfortunately I’ve got the same problem. John V answered with this, Quote again: -

“If your pump is running all the time with the key in the on position but the engine is not turning, something is wrong. It could be a bad relay or the air flow meter contact or flap could be stuck partially open giving the relay the false impression that the car is running”.

Could someone please tell me where and what the air flow meter is. I’ve only had the car for six weeks and as yet have no manuals, CD’s or any other info that might help. I have ordered an owners manual from 928 International that should be here in the next couple of weeks (would you believe the freight cost me as much as the book).

My pride and joy: - 1984s Auto 52kmls RHD imported from Hong Kong 99

Thanks in advance
Joe

jpitman

Joe,
Your 84 should be an L-jet injection- moving flap air flow sensor. This means you wont have the same air flow sensor is Iacast, whose car is K-Jet, or CIS. These, IIRC, run the pump for a few seconds on turn on, then off until spark signal keeps coming. If it runs all the time key is on, sounds like the relay has failed on, or is jumpered. Check the relay map pages at <a href="http://www.928gt.com" target="_blank">www.928gt.com</a> for 84, print a copy, locate the fuel pump relay, and check you fuse/relay board. If you have a relay in the relevant position, check there is no wire under it shorting 15-87; tap it to see if it will drop out? If no relay, and a wire is there from 15-&gt;87, thats your problem- fit the correct relay. If there is a relay, but its a generic, not the correct Porsche/Bosch item, this also wont care about lack of spark, and can be dangerous if left in place.
jp

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Thanks jp.
Had a look at the fuse/relay board, seems that fuse XV11 may be the wrong one it’s
a small silver relay part 141951253B with a VW emblem on it. Contact points shown on it are 30 85 86 & 87, in fact eight of these relays have been used on the relay board in positions 111, V11, XX1, XX11, X1V, XV1, XV111 & X1V they have 53 printed on top. Everything else on the car seems to work ok so maybe it’s the way it’s supposed to be.
Cleaned all the fuse contacts and checked wires, still no change.
Could you please tell me what IIRC stands for?

Thank you for taking the time.
Joe

Shane

Joe,

What jp is refering to is his memory. IIRC is an acronym for If I Remember Correctly.
You can go to: <a href="http://www.netlingo.com" target="_blank">www.netlingo.com</a> for a complete (and searchable) list of acronyms.

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

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Thanks shane,

OIC, TYVM, still got the problem with my fuel pump though.
Maybe in the morning I'll ring Porsche to find out the cost of replacing all the VW relays with the real thing.

Thanks again
Joe

jpitman

Joe,
Normal std relays have 4 pins - 2 for circuit to energise, 2 for the circuit controlled. The fuel pump relay usually has an extra narrow pin to get the signal from the distributor that it is turning. This is so that if the engine stops as in an accident, engine failure, the pump stops. Some cars use oil pressure signal for the same purpose. Do a search of rennlist archives for relays, and you should find a list of those that are std type, and those that are special.
jp

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Thanks jp
Off to bed now but after work tomorrow I’ll do the search thing. Interesting thing is the
Relay I took out of XV11 only had 4 pins, am I correct in assuming by what you have said that it should have 5.

Joe
<img src="graemlins/sleep.gif" border="0" alt="[sleep]" />

jpitman

Joe,

I'll check my spare tonight, but I'm pretty sure it does. I'll get the proper part no off it also, if my brains are working that early. It's really just a safety issue to stop the pump in an accident, in case you are not in any condition to turn the ign off.
jp

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Got your email John, thanks.
Things certainly don’t seem right; the little relay that I took out has only four pins numbered 30,85,86 & 87. What I’m doing now is taking the cover off the relay to see exactly what happens when I turn the key, start the car etc. May at least help me understand a bit more.
As per your suggestion I did a search for fuel relay on the list, WOW!. Unfortunately most of it is aimed at those that haven’t got a fuel pump working at all, quite the opposite to the problem I’m having.
I’ll post again when I find out what the cure is, or, if Iacast is out there maybe he could tell me how he fixed this problem

Your help is appreciated jp, thanks.
Joe.

jpitman

Joe,
You should find in the socket you have 12V on 30; when you get 12V across 85-&gt;86 it will pull the relay in and supply 12V (from 30) out to 87. There should be a diagram of this logic on the case of the relay. If there is a special (as in fuel pump) input there is another symbol for external trigger to enable, as well as the normal voltages. Its not critical unless the pump runs even with the key off, which will happen if you jumper 30-&gt;87. Some sockets have a 15 pin, which is only powered when ign is on, and is relatively safe to jumper to 87.

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Thanks John
Ok the relay works fine, performs just like you explained, everything is as it should be in the electrical dept. The original problem still remains though, the only way to stop the fuel pump is to turn the ignition off. I’m doing a search of the archives at present, hopefully there’s a cure there somewhere. There must be a pressure switch or something to tell the fuel pump that the engine isn’t turning over yet, or maybe having the fuel pump continually working is the way it’s supposed to be.

Thanks again,
Joe.
Next time I’m in Melbourne I’ll buy you one.
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

jpitman

Joe,
Its still a generic relay though, isnt it? Doesnt have the fifth pin? If its generic, its behaving as expected. SOme other cars have a feed to relay from starter (so it runs while cranking), and the main feed is from oil pressure switch, so the pump stops if engine stops. See if you can find somebody to borrow a proper 928 pump relay from and check if the behaviour changes.
jp

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Yes! I finally get it <img src="graemlins/c.gif" border="0" alt="[ouch]" /> seems logical enough. Trouble is the only other shark I know of is a 1985 and from what I’ve found out so far the relays for that model were different. However, I’ve ordered a new one (with five pins) and when it arrives there could be celebrations and dancing.

Thanks again john
joe

jpitman

What, a relay-haka? Send me a pic of you all painted up please!

Actually, the only 928 dance I know is the one you do when you get the timing belt replacement finished and working - see John Pirtle site. I did mine last Nov - gee this year has gone fast.

jp

WallyP

The fuel pump relay for the '84 model can be confusing, and I'm afraid that we (928 Specialists) didn't help any.

The '84 was a transition model, and the fuel pump relay is different on the USA/Japan models and the ROW (Rest of World) models.

The USA/Japan models still use the old complex fuel pump relay with the electronic circuit that gets its input from the ignition control box. This is what is shown on our web site.

The ROW models use the newer simple relay that is triggered thru the ECU. This type of relay is used world-wide from '85 up.

Since your car is presumably a ROW model from Hong Kong, the simple four-pin relay should be correct, and the complex relay should not be needed - at least according to the wiring diagrams.

Unfortunately, Porsche TOTALLY screwed up the '84 wiring diagrams, and they are essentially useless.

We should be able to use the '85 diagrams, which should match the fuel pump circuits in the ROW cars, but not the USA/Japan cars.

If your car is wired per the '85 system:
Pin 30 is battery power
Pin 87 is the pump
Pin 86 should be ignition power (hot when the ignition switch is on)
Pin 85 should run from W15 (plug W on the right end of the central power panel) on a brown/red wire to terminal 17 on the LH ECU.

Pin 85 is the key to this. If your car matches the '85 circuits, and if you have LH-Jetronic, with a hot-wire Mass Air Sensor rather than a moving-door Mass Air Flow sensor, then pin 85 should be grounded ONLY for a couple of seconds when you first hit the starter, and when the LH ECU thinks that the engine is running.

Hope that this helps!