dies when idling

citabra · Post by **citabra** » Thu Apr 03, 2014 12:48 am

Prior to a frame off restoration, I put a rebuilt Carter 950 YS carb on our 1953 M38a1 and everything ran fine. Now 2 years later when everything is reassembled it will only idle about 35 seconds before dying. If I rev it up for about 10 seconds or so it will idle for another 35 seconds and then stutter and die. I took the carb completely apart and everything looks great. Adjusted the float to 9/64's, fuel screw is 1.5 turns out and the idle speed screw is set to about 700 rpms. I am getting 4.5 psi from the fuel pump. Timing is spot on at 5 degrees BTC. I am going to blow out the fuel lines and check the tank for crud, but I would think if I am getting blockage it would reduce the pressure coming out of the fuel pump. Can a fuel pump have intermittent failure? Any ideas or thoughts are greatly appreciated!

BullRun · Post by **BullRun** » Thu Apr 03, 2014 9:30 am

Just tossing ideas out... is there a vacuum leak?, does the PVC valve work properly?, is there a loss of spark?, is the choke set properly?,

citabra · Post by **citabra** » Thu Apr 03, 2014 11:12 am

I have tested for vacuum leaks with propane around the carb and haven't found noticed the rpm's increasing. All the plugs are working great, and while it is idleing it sounds great. Choke is working fine. I believe the PVC valve is functioning properly. But to be honest I am confused on how the PVC valve could effect the idle. Could a leaking pvc valve reduce the vacuum enough on the intake manifold for it to stall while idling?

BullRun · Post by **BullRun** » Thu Apr 03, 2014 6:51 pm

Maybe bad gas?

citabra · Post by **citabra** » Mon Apr 07, 2014 6:42 pm

Following up. I tried "closing" the fording valves while it was idling and it picked right up. When I refurbished the valves I assembled the arm 90 degrees off. When I thought they were open they were actually closed. It idles much better now. Thanks for the ideas