924Board.org

Guest · Posted: Wed Jun 06, 2001 9:09 pm Post subject:

From: AznDrgn
Email: dy15@yahoo.com
Date: 06 Jun 2001
Time: 21:09:07

on my '78 924 NA when the key is turned to the on position the pump comes on like it should to bring the pressure up but it won't stop. Also as I understand it the starter won't turn until there is adequate pressure so I can't tell if the starter I just put up is working or not. Anyone got any ideas to why the pump won't stop? I checked the plate in the air intake it's not that.

Thanks

Guest · Posted: Wed Jun 06, 2001 10:18 pm Post subject:

From: Peter in AU
Email: Peter@planb.net.au
Date: 06 Jun 2001
Time: 22:18:10

EFI 101:

the fuel pump runs continuously while the key is on, excess fuel goes through the return valve and back to the fuel tank.

Reasonably sure that there is no link between the return valve and the starter circuit so that the starter won't activate until the return valve opens, signaling full fuel line pressure. Doing so would hide the problem - "my starter won't turn. Oh, that'll be your fuel system".

Peter in Sydney AU

Guest · Posted: Thu Jun 07, 2001 10:54 pm Post subject:

From: AznDrgn
Email: dy15@yahoo.com
Date: 07 Jun 2001
Time: 22:54:16

So your telling me that if I turn the key to the on position to listen to the radio the pump is just gonna sit there and cycle forever? I don't think that is right, on my other car it cycles up to pressure then will cut off until it is needed again. Also just a note, I dunno if you consider CIS injection as an EFI system but I don't think it is and the '78 924 has a CIS fuel system.

Guest · Posted: Fri Jun 08, 2001 5:11 pm Post subject:

From: Alex R
Email: polaris7@softhome.net
Date: 08 Jun 2001
Time: 17:11:43

I had this happen with the wrong relay in the fuel pump spot. If you take the normal, run-of-the-mill bosch relays (the kind with 4 prongs) and plug it into the fuel socket, the fuel pump will run when the key is in the run/accessory position, if you have the proper relay in the socket (has 5 prongs), it will pressurize momentarily, then turn off unless the engine is actively running.

Guest · Posted: Sat Jun 09, 2001 8:37 am Post subject:

From: Peter in AU
Email: Peter@planb.net.au
Date: 09 Jun 2001
Time: 08:37:20

AznDrgn,

OK, we obviously have different ignition key systems on our cars. On my '79 there is no "accessory" stop on the key switch, the accessory circuit goes active as soon as I insert the key and deactivates when I remove the key. So you are saying that you insert the key, click 1 the radio goes on, click 2 the noddy lights and fuel pump come on, click 3 the starter (should) lights up?

In that case, my only advice is to look at the wiring diagram in your Haynes.

Yes, I know that CSI is not EFI. It's just the most people don't know what MFI is and those that do tend to know that a fuel pump in an FI of any kind runs continuously.

Peter in Sydney AU.

Guest · Posted: Sat Jun 09, 2001 8:42 am Post subject:

From: Peter in AU
Email: Peter@planb.net.au
Date: 09 Jun 2001
Time: 08:42:54

p.s. excuse the dyslexia in my post. Geting late down here.

Peter in Sydney AU.

Guest · Posted: Sat Jun 09, 2001 1:28 pm Post subject:

From: larso
Email: l_porsche@hotmail.com
Date: 09 Jun 2001
Time: 13:28:22

1 thing to consider is a bad ignition module since it pics up pulses from the spinning rotor to run the pump.

Oh yah maybe your relay is sticking?