924Board.org

[mrborrie]

Hi All,

I bought a 1977 924 off a friend of mine who drove it into storage 2 years ago. When i got it the car would not ran, tank was pretty much empty.

Filled it up and it would now start very rough and die instant.

https://www.youtube.com/watch?v=EUNenZ7Mjpc

Now one month later i got my lift installed and now it wont even idle rough (was no fun pushing it on via my garden XD)

I did notice that the fuel pump wont make a noise when contact is on (and during start i dont hear anything ether)

And what i could not find in the Haynes manual is that the fuelpumpwire has been sliced and has 2 connectors to the tank ?! (they where undone, i put them back)


I have done allot of reading on the forums and i think my next steps are to bypass the fuel relay to see if the pump (or is there a intake pump too?) will start making noise.

Why the post? well i am looking for the joined forced of knowledge of the internet for good tips. I am pretty know with old Volvo’s but this is my first Porsche (next to a 986 I had a while ago) and back in the day I shared my knowledge on those things on forums. Hope to find a enthusiast willing to guide me through this.
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760 Turbo 86|Volvo 360 cup|Volvo XC90 04|Volvo C70 C 03|Volvo 745 turbo 86|Porsche 924 79|

[morghen]

If it starts but does not idle you may have a vacuum leak somewhere in between the air metering unit and the throttle body.
If it sat dry the fuel distributor could be a bit stuck but that should start working better and better once you put gas into it.
Look for vacuum leaks, split rubber parts, not tightened rubber parts..etc.

If it does not even fire once, see whats up with the fuel pump, it should run when ignition is turned on, then stop after a few seconds...or run continuously if relay has been hacked.
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https://www.the924.com

[mrborrie]

I had a 924 expert come over for a visit and he mentioned that i have the wrong relay in there.

The older models (4 speed ones) had a different fuel relay (477 906 059) with a fuse in there.
This one: https://rareporscheparts.co.uk/products/porsche-924-dme-relay-with-fuse-tester-477-906-59

The jump wire relay hack wont work on these models, this was news too me.

Since this relay is even more rare than the later ones i am looking to rewire it.

With the fuel pump directly wired the car starts and keeps running as you keep the key in starting position.

However the second you let it go the spark gets cut, I think perhaps the direct wiring of the pump and a direct wire to the coil could be a hack?

I am not the first to figure this out i am sure so any tips are welcome!
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760 Turbo 86|Volvo 360 cup|Volvo XC90 04|Volvo C70 C 03|Volvo 745 turbo 86|Porsche 924 79|

[mrborrie]

Car is running again! Yes the old style relay can be hacked by powering the coil directly
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760 Turbo 86|Volvo 360 cup|Volvo XC90 04|Volvo C70 C 03|Volvo 745 turbo 86|Porsche 924 79|

[copeina]

[mrborrie]

I found said switch under the airbox indeed. What does this switch do. does it keep the fuelpump from going on?

I am asking because i drove the car around with a separate battery indeed on the pump because no power on the OEM lines even with the newer style relay in there and the "coil" hack.

It could also be a fuse they hacked in somewhere since the OEM relay had a fuse and with this hack its gone.


Can you confirm for me what this switch does in the system?




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760 Turbo 86|Volvo 360 cup|Volvo XC90 04|Volvo C70 C 03|Volvo 745 turbo 86|Porsche 924 79|

[copeina]

[Raize]

Is that not the hot start solenoid though? I thought the plate microswtich was a blue connector directly on the airbox for the cars that had it...

The hot start solenoid drops the control pressure to zero when it's fired, so I guess if it was incorrectly constantly fired, it would shut off your car when the plate lifts due to giga-rich fuelling.

[!tom]

I did some diagnostics with how the fuel pump relay works in my car.

You can see the topic here: https://www.924board.org/viewtopic.php?p=289747
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78 924 NA
5-lug