Over fueling when engine gets warm

[CFD]

Car starts fine when cold, runs ok (perhaps a slight rough idle) but when it reaches the temp where the engine revs should drop to the 950 or so rpm, it suddenly starts over fueling, black smoke out the exhaust and cuts out. I can keep it running by giving it some gas, but its blowing out a lot of black smoke. If I cut engine and try to start it will only fire up when accelerator pressed fully to floor to give max airflow and clear it out.....

I disconnected the cold start injector, but didnt help.

Any ideas, suggestions that I can investigate? Thanks.....

[mark houghton]

Originally Posted by CFD

Car starts fine when cold, runs ok (perhaps a slight rough idle) but when it reaches the temp where the engine revs should drop to the 950 or so rpm, it suddenly starts over fueling, black smoke out the exhaust and cuts out. I can keep it running by giving it some gas, but its blowing out a lot of black smoke. If I cut engine and try to start it will only fire up when accelerator pressed fully to floor to give max airflow and clear it out.....

I disconnected the cold start injector, but didnt help.

Any ideas, suggestions that I can investigate? Thanks.....

Sounds like you may not be getting any electrical power to the WUR, which is required to heat up the internal element and cause the cold start control pressure to rise after a couple of minutes...thus leaning out the mixture. Your symptoms indicate that the WUR never leaves its cold start mode.

Pull the plug from the WUR, force your pumps to run by either starting the car or unplugging the blue/green plug behind the the fuel distributor head with the key in the on position, and put a voltmeter across the terminals of the plug. You should be able to read voltage there. If I recall, the circuit that controls the voltage to that plug is tied in with the rear fuel pump relay.

[oilonly]

Did you check ou this thread CFD?

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/615284-bad-idle-black-smoke.html

[CFD]

Originally Posted by mark houghton

Sounds like you may not be getting any electrical power to the WUR, which is required to heat up the internal element and cause the cold start control pressure to rise after a couple of minutes...thus leaning out the mixture. Your symptoms indicate that the WUR never leaves its cold start mode.

Pull the plug from the WUR, force your pumps to run by either starting the car or unplugging the blue/green plug behind the the fuel distributor head with the key in the on position, and put a voltmeter across the terminals of the plug. You should be able to read voltage there. If I recall, the circuit that controls the voltage to that plug is tied in with the rear fuel pump relay.

Thanks Mark - will check that this evening. Much appreciated.

[CFD]

Originally Posted by oilonly

Did you check ou this thread CFD?

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/615284-bad-idle-black-smoke.html

Thanks for the link - have read the thread now, so will check through all the suggestions there as well.

Thanks guys!

[CFD]

Just had a few minutes to check the WUR this evening - so I have power at the plug - I didn't get a chance to do any further checks, but however right from cold start now it is overfueling - not just when the engine is warm as before. So it seems the problem is getting worse. I will check the vent hose from the WUR to see if the diagram is damaged and also check voltage at the AAR.....gradually work my way through the list of recommendations from the other thread. Let you know how I get on....

[mooney265]

dimpled diaphram on the WUR? That just happend to another Pelican a couple weeks ago...

You'll need CIS gauges to check all of your pressures...

[CFD]

Problem traced to cold start injector. Disconnected it runs fine - so need to determine if its the thermo switch or the injector - but it seems to be the issue. However, I am in the process of putting together a test kit for the injection system as I will a thorough check at all points to ensure everything else is workng correctly and I have the correct pressures under the various conditions. Thanks for the help guys!

[Ronnie's.930]

If you are not already aware of this, post #16 of this thread describes how to test the thermo time switch:

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/564743-930-78-3-3-thermo-time-switch.html

[CFD]

Originally Posted by Ronnie's.930

If you are not already aware of this, post #16 of this thread describes how to test the thermo time switch:

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/564743-930-78-3-3-thermo-time-switch.html

Great, thanks for that. I was thinking of taking it off, but its a nightmare to get at it with all the turbo pipework in the way, so thats a neater method for sure!