Hard start problem solved

[Aleksander Mierzwa <alex@matrix.pl>]

Hello list,

Seems like a good stuff for the archives. As you recall, the symptoms were

- difficult to start when cold, starts but has no power when hot
- fuel pump running, residual pressure OK
- frequency valve not working
- cooling fan not running with A/C on

And the cause was... faulty fuel pump relay. The solder joints for two
terminals were cracked, causing intermittant connection. When you look in
the wiring diagram it makes sense - apart from the obvious function of
activating the fuel pump, the relay also supplies voltage to the frequency
valve, wastegate solenoid and carbon canister valve, as well as sends
signal to the afterrun fan controller (which, in turn, activates the fan
1st speed relay when told so by the A/C controller). With frequency valve
not working, the mixture was extremely lean. Thanks for all the replies,
I'm glad this time it was such a simple fix. The engine still vibrates at
idle, though :-(

Aleksander Mierzwa
Warsaw, Poland
mailto:alex@matrix.pl
87 Audi 5000CS turbo (mine)
88 Renault Medallion wagon (mom's)
91 mountain bike (just in case both cars break at the same time :-)