i have a 1985 280 SE. I am having problems with the fuel system. it is acting like it is starving for gas. Question: What is my required fuel pressure needed to run the engine? I am looking at replaceing the fuel pump again. i changed it out when i first was given the car like 2 years ago. Also, I see fuel pumps for cheaper online. How is the quality with these pumps? Will they give me the pressure i am needing? Any other itmes on the car that may cause this type of symptom? Thinking about changing out the filter while I am at it. Also I should note that I emptied the tank, puled it out, ran some acetone through it, blasted it out at the car wash, dried it out real good and put it back together, then replaceedthe filter about 6 months ago.

Fuel pump replaced 2 years ago and a filter replaced 6 months ago....I'd say you better properly diagnose the problem before you throw parts at it. Prime the pumps and crack open the main fuel line to see that fuel is indeed being passed by the pumps. If it does, check everything from that point forward. If fuel seems to be reaching the injectors, try to check the air.

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1990 190E 3.0L

I have not considered the possibility of not being aboe to breath. I will look into that. It starves out intermittently though. It runs fine and will randomally start to act up. I slowly let off the accelerator and it gets better.

Assuming it's a CIS system, have you tested the fuel accumluator? I had intermittent hard cold and hot starting problems, which got progressively worse. I did a simple on-the-car test of the accumulator. It failed, and a new accumulator solved the problem.

The accumulator developed an internal leak, which made it difficult to maintain proper system pressure. It may start out as a starting problem, but get progressively worse and cause the engine to run poorly or stall.

Search my handle for recent threads I started on the subject, including the simple on-the-car test.

I think a lot of fuel pumps and FPRs get replaced, when the problem is an internally leaking accumulator. Of the three parts, the accumulator is the least expensive and easiest to change.

Duke

By all means replace the fuel filter. From your narrative, the filter is an unknown quantity.

With respect to "starving for gas", could you expand a bit? What are the observed symptoms, and when do they occur? Is there a starting problem, and does it occur with a cold start, or a hot start? Is there a lack of power when large throttle openings are employed? Stumbling & misfiring at small throttle openings, or at large openings?

System fuel pressure w/engine idling: 5.0-5.6 bar.