Another Demon question.
Thread Starter
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
Another Demon question.
My 825 Mighty demon was running great. All of a sudden it started to let me down. It seems at an idle only sometimes it will go rich and the car will die. I come to a stop normal driving and then go to take off, normal driving again and it will stumble and die on occasion. I put in my LM1 wideband and find tha tis is richening itself up for no reason. Under WOT it runs perfect. Readings are all good. I pulled in a thought maybe power valve. Myusual test for this is the finger on the vent tube. It immediatly floods itself out. This has happened many times before and a new PV is put in and we are good to go. I think OK new PV and should fix the problem. Well new PV and it still floods the engine out with the finger over the vent tube. Kind of stumped on this one. It will only stumble like this once it gets to operating temps. It has died on me in 2 intersections. It starts back up like it had to much fuel but will clear itself out after starting and run OK for a while. Once cruising it seems to be OK. It is only when coming to a stop and trying to leave a light, or on a slow down for a turn and light acc. away from a turn . If I jump on it it is OK. 
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
The only time my demon went from running fine one minute to bucking and snorting the next was when the needle and seat screwed up. I just replaced both pri and secondary with .110 titaniums for alternate fuels
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
i like the needle and seat theory.......at WOT the needle is open all the way.....at idle its stuck a little making the car run rich and stumble
