Mercedes-Benz Forum banner

fuel air mix / testing fuel pumps and pump pressure

3K views 0 replies 1 participant last post by  william.wood 
#1 ·
for some reason my 420SEL uses a 3.5mm allen to adjust the mixture you can see where others besides myself have tried to use an 8mm and all it did was spin in the hole and wear down the aluminum but it doesn't adjust anything

also some manuals say to use a 3mm.. but that didn't do anything either. too small.

frustrated to get the fuel mixture to change, i one day decided to keep using different size allens until one droped in. 3.5mm was the lucky no.

i adjusted the air mix using a dwell meter to the 20-25% range but it was still idling around ~1000 despite putting in a new Idle control unit, spark plugs, wires and cleaning out the idle control valve of all soot using carb cleaner, even though it was already working properly. it also passed IL emissions 1 week ago with flying colors.

so;another 1/4 turn leaner got it into the propper RPM ball park. is that ok even though dwell percentile is out of range?

also the manuals say to jumper pins 7 and 8 on the fuel pump relay socket to get the pumps to turn on for testing.
but my relay doesn't have a pin 8 or a socket for pin 8 ?? so then what do i do? the wiring diagram shows Battery power coming in on pin / socket no. 1, do i jumper pin 7 to that instead, to get the fuel pumps going?
 
See less See more
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top