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Fuel System Question

1K views 4 replies 4 participants last post by  JC201 
#1 ·
So when I got the car back in Nov. of 2013, the car ran strong and steady. It always started right up. In my infinite wisdom as a newbie to the scene, I decided to use high octane gas with cleaning products in it and also used not one, but a couple little bottles of gas/injection cleaner additives in with each fill up. Now the car takes at least two cranks to turn over and kinda sputters for a bit until warm. There is sometimes a loud whining sound coming from the truck area, which I suspect is coming from under the gas tank. I has started to not want to turn over when parked after a drive (I know this may be an indicator that the fuel accumulator may be shot). Did I do this to the car with all the cleaners? Did all the cleaners release gunk into the fuel system? How do I correct it.
 
#2 · (Edited)
The whining under the trunk is probably the electric fuelpump. It is possibly you removed a lot gunk with the cleaner, it could have clogged the fuelfilter next to the pump, or the strainer inside the tank.
These items are not difficult to change nor expensive and may be a good start with no downside.
When you drain the tank to change the strainer ( accessible from the bottom), check the cleaness, no point to refill if you immideately clog the filters again.

A simple test for clogged fuel system is to disconnect the fuel feed line at the fuel distributor, measure the time it takes to fill 1 quart (1 litre). To do this you need to disconnect the the black/red/white line to the fuelpump and apply +12V to it. The MB spec is 30 s, I measured about 12s with new filters and lines. My fuelpump drew about 2,2A during this test.
 
#5 ·
My situation was different from yours in that my 450 sat in a garage for years. Not entirely my fault, but that's a different story. I replaced the fuel strainer, fuel filter, fuel hoses, but the real culprits were the accumulator and the Warm up Regulator (WUR). I did the fuel quantity test that hchaugli recommended and the accumulator test that dgosh28 recommends. If the accumulator is shot, it will fail the fuel delivery test and the car will not start quickly. The thing that resolved most of my problems was cleaning the clogged screen filter in the WUR. Sounds like you might need to do that.

JC201
79 450SL
 
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