CIS control pressure data...does this look correct?

[Elombard]

I have been having strange intermittant and high idle problems on my 79 Euro. I fixed a problem with no voltage to the AAR and WUR. But still cant get the idle and cold start to behave properly. The system pressure is good. Here is the data from my last cold start. Could this be a funky WUR? A few days ago I had a semi cold pressure of about 24 rising to about 44 psi. Thats where I think it should be....FYI it was a cold dry day here in Atlanta ~ 45 deg out side.

T = 0 Start up, car sounds rough, idle 1000, no perception of WUR AAR Warm up (Idle falling over ~2 min)(I did have this yesterday)? Pressure 14 PSI

T= 5 min Pressure 18 PSI eyes burn - smells rich

T = 8 min shut car off for 30 sec, restart, Pressure 20 psi, idle hunting, still burns eyes

T = 13 min Pressure 24 psi, no hunting idle, no rich smell, idle rising.... pressure rising to 28 PSI. Shut off car

T = 15 min restart car pressure 24 psi, same as above

T = 17 min pressure up to 28 psi shut off car

T = 21 min restart after disconnecting and blocking all hoses to Decel valve. No change in running. Pressure now at 32 PSI???? This pressure appeared after removing the plug from the small vacuum line from the WUR to Decel Valve (whistled) and replugging. Seemed to jar the WUR....

I believe I proved to myself that the decel valve has no leaks in the diaphragm through unplugging and re plugging various lines one at a time while the car was running.i.e. I would unplug one line and it would act like a vacuum leak, re attach to decel valve no vacuum leak etc.


Does this look like fairly normal WUR pressure behavior? I wonder if the plug thing in there is sticking a little?? The jump up in pressure after opening the vacuum leak and reclosing quickly seemed odd. I tapped on it several times - does not seem to make any difference.

I probably need to pull the cold start injector and make sure that does not have some kind of fuel leak.

ANy other thoughts or easy tests I could do??

The system pressure (pump car not running) and the holding pressure after shut off are normal.

I was playing with the idle air bypass adjustment screw through out so I cant report what the idle was doing acurately through the above test.

Thanks

[echrisconnor]

Looks like your cold pressure is off in the later part of your thread, or just that the pressure isn't increasing after startup. However, in the first part of your message the values look right. Are you sure the heating element in your WUR is working?


I did this test a few days ago and have it fresh in my mind. If you have your gauges, you should see the fuel pressure raise very quickly after startup. By about 3-4 minutes you should be fully leaned out. Looks like you're really rich due to low pressure with a warm engine.

See this post here:


System/Control Pressure test for dummies?

[cmonref]

Your fuel pressure is not rising as fast as it should after engine start. eChrisConnor is right -- it should stabilize at the "warm" value within 3-4 minutes of running.

The rise in fuel pressure in the 3-4 minutes is cause by internal heating in the WUR. Without that interneal heating strip working, the pressures would rise, but much more slowly -- kinda like you describe.

You say you have confirmed power to the WUR. What is the resistance across the terminals of the WUR? I do not know the spec, but would not be surprised at abut 35 ohms. An open circuit means no heating inside the WUR, which would cause the pressure to NOT rise --just like your pressures do NOT rise.

[Elombard]

Thanks Brian, I checked the resistance on the AAR but not the WUR. I was so focused on my idle problem being air related. The resistance on the AAR is ~33 so I bet your right at ~ 35.