Quote:
Originally Posted by 97 SL320
Things I'd check.
In tank strainer, if this is clogged, the pump will cavitate.
Check fuel pressure. If the return line is crimped, the pump will be straining against it's internal over pressure relief. If this has occurred, I'd expect the motor to go rich and trip a code though.
Does this have a " drive shaft through the fuel tank " like the W202 your car is based on? If so, these use a venturi pump to get fuel from left of tank to right where strainer is.
If there is a pulsation damper anywhere on the pressure side of the pump, a failed one may cause this noise. The damper might even be at the engine or on the fuel injector rail. It will probably look like a fuel pressure regulator if it has one.
In any event, I'd be tempted to run the pump manually then poke around the engine to see if the noise is coming from the fuel pressure regulator.
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Thanks.
I have done all that and more since I am battling here since 2015 with this rubbish.
There is no damper andit is not a split tank like W202.
It is not the regulator at the engine and the source is the pump transmitting the noise back into the fuel tank via the 15mm (unobtainium) thick hose from the pump into the tank. The whole tank then amplifies this back into the rear wall of the cockpit.
The fuel pressure is correct and I checked it just after replacing this pump again last week.
The only thing I have not done is change that (15mm) hose. It could be too hard and transmit the vibrations but I have no new one to compare to and they want $125 for a new one here!
The darn noise changes with voltage changes like when the indicator is on or when the brake lights are on.