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W123, W116 Wagon
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Discussion Starter #1
My W116 280SE (M110) being converted to MS Efi

I am using back the original D-jet injectors and now I am facing an issue with the fuel pressure regulator

The D-jet original Fixed Pressure Regulator(FPR) is fixed pressure(regardless of manifold vacuum).

MS recommends "Vacuum Referenced Fuel pressure regulator"(VRFPR) which will increase the fuel line pressure on hard acceleration.

I read that if I were to FPR, the injectors will have to stay open longer, generating a lot of heat and possibly fouling the injectors.

I like the idea of VRFPR but I am worried that on hard acceleration, the fuel pressure may be TOO high for the D-jet fuel delivery system (damaging the injectors and possibly bursting the soft rubber hoses).

Using VRFPR, I am thinking of setting the pressure at max 3 bars(I read that Bosch claimed that the D-jet can hold 3 bars) but at idling, the fuel pressure may be too low, injectors have to stay open for longer period(thus fouling them) and insufficient atomizing.

Let me know your thoughts.

Thanks in advance.

NPK
 

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W111 Coupe
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1,214 Posts
You should use a VW Vanagon L-jet vacuum actuated FPR. It will bolt right in place of the Djet one and connect to the hoses. The small port on top is for a vacuum hose. L-jet is also using hose top injectors, and I'm ready to bet that same injectors are being used on some L-Jet and D-jet applications.
 

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1971 280SE 3.5 Coupe
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415 Posts
I have been doing some research on my upcoming MS project that might be usefull. Ford 19lbs injectors fit perfectly if you install D-jetronic pintle caps on them and will give better resolution. The originals are somewhere in the range of 50lbs and are low impedance. You can also then use a O-ring fuel rail and do away with the problematic short hoses between the injector and the fuel rail. You can buy blank fuel rail and drill it for the injectors and fittings.
It is also very easy to convert to Ford EDIS distributorless ingition. The main problem is the crank toothed wheel which I have had designed and fabricated to fit over the crank pulley up against the harmonic balancer. Then MS can manage your fuel and ignition. I would only go one step at a time.
 

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W111 Coupe
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Tony,

The hoses are problematic when they are 20 or 30 years old. I think you're OK with all new ones. You could use Volvo 200cc injectors I believe high impedence, but should be confirmed. You could also look into Vanagon ones. They are hose top injectors and a direct fit with the Djet fuel rails. It would save you a lot of fabrication work.

I used Nissan Z 280 Turbo hose top 280cc injectors for my 5.0 Megasquirt conversion with a 4.5 Djet manifold and fuel rails.
 

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W123, W116 Wagon
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Discussion Starter #6
To update...

1. I cut 36 teeth onto the harmonic damper, converting it into a trigger wheel.

2. I am using back the original D-jet injectors with a bank of resistors to convert the injector impedance.

3. I changed the fuel pressure regulator to Vacuum reference ones...(at idling Fuel Pressure is about 2 bar...and at min vacuum(WOT) pressure is about 2.5bar.

Car runs well and smooth
 
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