jumpinjimmy

I'm still struggling with my 1981 928 that's running really rich and has no power. I've tested the resistance of the WUR and it's showing 31 ohms which seems normal so tomorrow I'll check voltage with the car running to make sure that's functioning ok. Someone has also suggested checking if the cold start valve is functioning properly or whether it may possibly be stuck. Any ideas on how to test for this or check it?

Steve

jpitman2

Different WUR have different resistances (bimetallic heater windings) in those I have opened. What you need to read is the control pressure , not resistance.
Cold start valve - remove from plenum, put in a jar, at least point the end into something (have extinguisher handy), jumper the pump relay - with no volts applied to CSV, should not see any fuel at all, should only spray with +12V over it. If its ok, the thermotime switch may be suspect - staying closed when it should open. Easier way to test CSV is just pull power from it and see if rich running stops or improves. Pulling power from thermotime should also cut power to CSV.
jp 83 Euro S AT 53k CIS

jumpinjimmy

Thanks, I'll have a look at it today and post results.

Steve

jumpinjimmy

I've gone over the WUR and while there was a few extremely small bits of trash on the filter, nothing unusual. I decided to have a look at the rich/lean screw. I turned it slowly by half turns until the smoking stopped and the engine regained it's power and stopped backfiring. Seems to be running fine now. I had to turn it what I consider to be a lot of turns.....3 full turns counter clock wise. Anyway, all seems fine now. I'm curious at how it could have gotten out of adjustment.?????

tasar2180

Perhaps your fuel pressure has changed due to a WUR fault? (or something else). Then you have adjusted your mixture to compensate for the fuel pressure issue. I think you need to measure fuel pressures to sort this out properly.

Simo 83 CIS