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1977 450 sl convertable
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8 Posts
Discussion Starter #1
Did some searching but not able to find answer.

on 1977 450 sl, does the fuel pump run when key is turned on?
Seems i remember ours did, now it does not run until the car is started.

Next, how loud is the pump? i can hear pump running from 10' away from car while running.

This all goes back to starting issue.

1-It takes more than 5 to 10 seconds of cranking before it will fire, Sometimes starts right up.
2-Sometimes starts right up and idles fine but hesitates and backfires when you give it some gas (in neutral), have to hold pedal down for 20 to 30 seconds and back fire goes away and runs fine after that, this seems to happen more frequently.

any suggestions?

Thanks,

Scott
 

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Registered
1977 450 sl convertable
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8 Posts
Discussion Starter #3
ballast

This has helped a lot in understanding how this thing works.

Have traced issues to the ballast resistors, one is cracked and started checking for loose wires while running and like magic starts to run normal

I want to replace them both.

One has # 0 227-901-013-silver color
Other has WZ04-2-Blus color

What are the correct ones to use and where to get them?

1977 450sl

Thanks,

Scott
 

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It Is What It Is, Dude
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22,841 Posts
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0227901013 is the Bosch p/n for the 0.6 ohm silver ballast. 0227901012 is the Bosch number for the 0.4 ohm blue ballast which interchanges with the Beru WZ04-2. Should be available at any quality parts store.
 
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