540i misfire and start prob

bmw 540i e34 takes forever to start and when started there is a misfire
fixed a cracked manifold.replaced fuel pump but still no results if someone knows what the problem is help

Check the crankshaft position sensor. Should be 540 +/- 10% ohms. Check main relay. Check fuel pump fuse and fuel pump relay. Check fuel pump.

Get the Bentley manual and read, read, read.

Good luck.

i would check spark before fuel. seems like a bad coil or plug even...

I would be inclined to check plugs and coils. I suspect coils can be tested and the Bentley manual, already reccomended, should have the specs.

When you replaced the fuel pump did you verify fuel pressure? Can you hear the pump run? If no pressure follow the relay advice from BMRLVR.

Check for other vacuum leaks, cracked hoses, fittings.

thats the thing.8 bosch spark plugs was put in.as for coils there was one dead so i replaced.fuse,relay that was the first thing i checked.as for the sensor where to get new one remember south africa

Originally Posted by windgat

thats the thing.8 bosch spark plugs was put in.as for coils there was one dead so i replaced.fuse,relay that was the first thing i checked.as for the sensor where to get new one remember south africa

Buy a parts car.

I would go with others and check for spark. If it's not spark plugs or coils and you replaced fuel pump, I would check for fuel pressure. Lastly, check for compression between 142-159 psi. Are you throwing a code? I'm still new to OBDI but it might point you in the right direction at least.