Author Topic: Short Bosch Fuel Pump questions  (Read 3119 times)

IXLR8

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Short Bosch Fuel Pump questions
« on: May 12, 2011, 02:49:52 »
Hi--

I have a few questions about the short Bosch fuel pump and its fuel connections. I have a 65 230SL, VIN 10467

I see some some cars with a "T" fitting in the fuel supply line with one side feeding the injection pump and the other side returning to the fuel pump.  Other cars have only a single fuel line feeding the injection pump.

1) What is the purpose of the return line?

2) Where does the return line attach to the fuel pump?

3) Why do some cars have the "T" fitting and others do not?

How can I know if my car should have a "T" fitting or a straight feed line to the injector pump?


Thanks in advance for your help.

Joe

ja17

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  • USA, OH, Blacklick
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Re: Short Bosch Fuel Pump questions
« Reply #1 on: May 12, 2011, 03:54:01 »
Your injection pump has a return fitting on the IP. It is where the fuel returns to the fuel tank.

These fittings act as regulators creating pressure in the fuel system before the fuel returns to the tank.  Some refer to them as regulators.  There are two types of return fittings. One has a small hole (orifice) to restrict fuel return. The other type has a spring loaded check valve.  If your pump has the fitting with the orifice do not use the "T" by-pass  fitting. If your has the check valve fitting, you can use the bypass. 
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

George Des

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Re: Short Bosch Fuel Pump questions
« Reply #2 on: May 12, 2011, 11:10:06 »
Joe's right. You should not need the T fitting on your car if you have the R11 FI Pump that was original to the car.

George

IXLR8

  • Guest
Re: Short Bosch Fuel Pump questions
« Reply #3 on: May 12, 2011, 18:04:40 »
Thanks, Joe and Des--

I have an R11 IP and a single line fuel feed.

So, I'm done below the car and now onto the top side.  18 months into what I anticipate being a 36 month restoration journey.

Thanks to all Pagoda members for their encouragement and vast reservoir of knowledge.


Joe