96 C280 Fuel Pressure Gauge? - PeachParts Mercedes-Benz Forum

Martineau Gauda · #1 05-22-2003, 11:31 AM

Hi,

I need to find an adaptor to allow rail fuel pressure reading on 96 C280. Is a fuel rail connector available on this car and is it a Mercedes proprietary fitting. Quick Disconnect?

I have a fuel pressure testing set used for the testing of the injection system on Rolls Royce, Bosch CIS (90 psi system) and want to use the gauge set for the Mercedes also. The fuel pressure gauge is 100 PSI but I am sure I will need a rail adaptor to read the Mercedes rail pressure.

Thanks

mbdoc · #2 05-22-2003, 05:28 PM

The fitting is the same as an old R12 a/c charge hose. Very easy to come up with that fitting size & OR hose.

Martineau Gauda · #3 05-22-2003, 05:37 PM

Great!

I assume it is the brass fitting that sticks out on top of the intake manifold with a brass cover.

Is this a high pressure > 70 psi system or one that is about 30 psi

Thanks

Arthur Dalton · #4 05-22-2003, 06:01 PM

I made one from an old a/c line end.. Use the end that has the pin to push the schreader valve in..

pressure is 3-4 bar range

Martineau Gauda · #5 05-22-2003, 06:18 PM

Found the right adapter for the pressure set I have and took the reading.

The reading is 48 PSI. I think that is right where it should be.

I am starting to take and record certain readings on the car while
it is operating properly so it will help during a future problem diagnosis.

Thanks for all your wise and talented help.

Arthur Dalton · #6 05-22-2003, 06:47 PM

FP testing calls for more than running pressure.
The first reading is at idle
You are looking for 3.2-3.6 bar -This test both the pressure to injectors and the regulator for specs...

Next test is to disconnect the vac line to the regulator [ in front of the test port]
The pressure should now increase to 3. 7-4.2 [unregulated pressure / actual pump pressure].
Next test is to turn key OFF for 30 min and see if pressure HOLDS ...spec on your car for this test is no less than 2.5 bar after 30 min.
This test the pump check valve and injector seating ...

There is also a flow test that can be done to assure vol, but that is a different test at the same port[ not a pressure test]

Bar conversion to PSI is 14.5

As you can see , with these different test, one get a wider range of diagnosis...one can deduct pump, bad filter , leaky injectors, bad reg, etc....

Martineau Gauda · #7 05-22-2003, 10:26 PM

Arthur,

That is exactly the detailed procedure information that is very important to me.

Thanks for your contribution.