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Fuel pump valves

  • stan73
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  • 560 SL 107.048 1987
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29 Nov 2021 16:51 #286478
by stan73 Americas (USA/CAN) 560 SL 107.048 1987
Fuel pump valves was created by stan73
Dear all, I have a problem with hard start engine after changing of 2 fuel pumps, spark plugs, fuel injectors , all filters, all fluids. The car didn't have a problem prior this. I did it as regular maintenance after buying the car from USA. With cold engine I must crank few times before engine start.   I found this video :  www.youtube.com/watch?v=XLKMqatAcxk and I thought about fuel pump check valves I have replaced pumps with BOSCH part number: 0 580 464 125. (local store gave it as replacement for A0030915301) but didn't know and check this valve, I thought it is normal connection not valve. In the other hand I found out on the old pumps this connection don't have  spring inside the holes.(so it is the normal connection nozzle). Maybe my old pumps have some valve inside? The logic is that those valves stop fuel to return the fuel in the tank ? Please share your experience. Best Regards Stan  

Stan
560SL, 1987

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  • Dr-DJet
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  • Schweiz
  • 450 SL 107.044 1973
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29 Nov 2021 17:04 #286482
by Dr-DJet Schweiz 450 SL 107.044 1973
Replied by Dr-DJet on topic Fuel pump valves
Hi Stan,

I am not quite sure I understand your question. But you need this non-return valve or fuel pressure cannot be kept high in fuel accumulator. But normally it is rather a leaking accumulator than a broken valve.

Viele Schraubergrüße - best regards, Volker alias Dr-DJet und K-Jet Forscher, Admin und Betreiber dieser Webseite
Alles über D-Jetronic und Zündung auf jetronic.org

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  • stan73
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29 Nov 2021 17:30 #286484
by stan73 Americas (USA/CAN) 560 SL 107.048 1987
Replied by stan73 on topic Fuel pump valves
Dear Volker, 

According EPC there is valve part N: A0000900310 (picture attached).
I'm not sure that my new pumps have such valves inside nozzle. (old pump don't have it either, maybe pumps are different ?)
As I know accumulator is holding pressure and must exits fuel to tank only when fuel pressure is too high. 
I believe logic of such pump valve is to hold pressure inside system when engine not running. 
If not what is purpose of those valves?

BR 
Stan    

   

Stan
560SL, 1987

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  • Dr-DJet
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29 Nov 2021 17:36 #286485
by Dr-DJet Schweiz 450 SL 107.044 1973
Replied by Dr-DJet on topic Fuel pump valves
Hi Stan,

nu accumulator shall preserve fuel pressure together with non-return valve. Pressure regulator lets fuel return to tank. All your pumps should have this valve and it is screwed into pump exit. At least on 1 picture I saw it.

Viele Schraubergrüße - best regards, Volker alias Dr-DJet und K-Jet Forscher, Admin und Betreiber dieser Webseite
Alles über D-Jetronic und Zündung auf jetronic.org

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