1995 BMW 318is Base 4 Cyl 1.8L
Why tach and fuel gauge start jumping and die/drop.
After swaping original 1.8is engine for 525 (1992) engine tachmeter and fuel gauge start jumping after diriving for a while with warm engine and die/drop to 0 eventually. They last longer if i turn on some additional electrical devices ( fog-light, blow to max, rear window heater) but in the end they still die.
I think that that you are using the 318is system, they don't match with the 525. The 325 and the 525 is basic the same engine There is alot more to do the system can't handle the work load.