mtoronyi

I have a 1978 5 Speed that has a running issue. The car will start up easily and run until warm. Once the car warms up and I blip the gas pedal to drop the idle, it dies. The car won't drop to a warm idle on its own.

After the car dies, I can start it right back up, however I have to keep my foot on the gas to keep it running. If I let off the gas she dies immediately.

I have replaced the two fuel pumps and checked the flow rate on the return line. It's right at the 1360cc. I also checked the pressure going into the WUR and it shows at about 29lbs cold. It does not appear to change when I plug in the wire to warm it up.

I can't quite determine if it is the WUR or the fuel distributor. Thoughts?

mtoronyi

Anyone have suggestions about what to check for the issue? Thanks

The Deputy

Did the issue show up suddenly (while car was in normal running condition prior)...or after sitting for several months?

Do these issue continue to be a problem, if you can keep it running long enough to get it warmed up (after twenty minutes or so of running)?

A little more history and conditions may help us figure out the issue.

Brian.

mtoronyi

Showed up suddenly while driving the car on nearly a daily basis. Ran fine one day, wouldn't start the next day.

Warming it up doesn't seem to make a difference. The car will run for 20 minutes to warm up, but as soon as I touch the gas pedal and let off the car will die. During warm up the rpms never drop down, just sits at about 1,500 rpm.

Guy

Time to break out the fuel gauge and get some readings to disgnose

LT Texan

Idle adjustment screw?

Is the idle just set too low?

mtoronyi

Idle was fine before it stopped running. I have adjusted the idle screw to see if that would help.

I've tested the fuel rate on the return line to be appx 1350. System pressure is about 69psi and pressure at the WUR inlet is 29psi. The pressure did not rise on warm up so I've ordered a WUR rebuild kit.

LT Texan

I guess that means that you opened the idle screw all the way and it still would not run at idle?

If the engine runs fine except it will not idle, I don't know why you are rebuilding the WUR.

mtoronyi

I did adjust the idle all way out and all the way in. No change. I'm rebuilding the WUR because the pressure didn't climb from 30 to 42 when I plugged it in so it would warm up.

Something broke that took a perfectly running car to not running overnight.

I've gone over so many different things looking for an obvious issue and haven't found one. So now I'm trying to test various things like fuel pressure. When I find one that's not right I'm fixing it.

James Bailey

The CIS 928 nor any other 928 has any "blip the throttle down to ide" feature....your year the aux air valve slowly closes over time as it is electrically heated....mounted low under the intake right rear it bypasses the throttle body...

GlenL

Check the hoses and for a vacuum leak.

LT Texan

So at part throttle it runs fine?

Is it only when the throttle plate is completely closed that the engine will not run?

Maybe the idle speed adjustment valve is not flowing air bypassing the throttle plate correctly?

Tardis928

Hi-

I had a similar problem on my '79. I had to tweek the CIS and idle combination. The idle is set higher than I like it, it is in the 1500-1600 range but it has been starting and staying lit reliably. One of these days I'll take a deep dive into the Bosch CIS manual and see if I can get the idle back down to a normal range. But it is working and I am happy with that for now.

Greg