Hi,

I had the same problem with a 91 245 (LH3.1) I've been working on--stumble going over bumps, or when slamming either front door. After putting in a new pump relay I was still getting the same problem. Replacing all of the fuses didn't help either.

When I started tracing the wiring to/from the fuel pump relay and I found an intermittent open in the red wire leading to the pump relay. On our car there is a splice in the wire about 14" up from the relay where 4 or 5 smaller wires joint the bigger wire going to the relay.

I found that if I flexed the wires around the splice while the car was idling, it would stumble. I took the original splice apart, cleaned everything and used a new connector to put all of the wires back together. So far it appears to have fixed the problem.

BTW remember to disconnect the battery before starting the work, as on our car the red wire(s) to the pump relay are always "HOT" and are not protected by a fuse.

Hope this helps!

Best,

Steve A-