I've got a starting issue on a 91 300CE, see post:

91 - 300 CE - start and die, start OK then...

I'd like to test my fuel accumulator first: how can it be done?

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From 300CE to SLK230K

I went through a 2 week diagnosis on my '90 300E a couple years ago dealing with a similar problem with my fuel system. The fuel accumulator has a small bleed off hose on the back of it, which goes to one of the fuel lines near the pump(s). As it was explained to me, the purpose of this line is to capture any fuel which may leak through the internal rubber diaphragm (due to breakdown of the rubber), and send it back to the fuel system. The way I was shown to test the accumulator is by taking the small line loose where it's connected to the other fuel line, drain any fuel, and pull a vacuum on it using a vacuum hand pump. It should hold a vacuum, if not the internal diaphragm is faulty, and is likely allowing precious fuel pressure to leave the accumulator & cause increased starting times. Hope this helps, & hope I'm not too far off my rocker!

BTW, if nothing else jumps out at you as the cause of your problem, take a hard look at your fuel pump(s). It took me approx. 30 minutes of watching my fuel pressure test gauge while sitting underneath my car (on a hoist), before I finally saw the pressure drop drastically- at the same time I could hear an audible change in the way the fuel pumps sounded. I could actually feel the pump straining when I put my hand on it. I'm not sure if your car has 1 or 2 fuel pumps- mine had 2 & ended up finding that both were bad- replaced both & problem solved.

Thanks for this very usefull information, I better understand the behavior of this fuel accumulator now.

Could please you recommend an equipment to check fuel pressure? Where do you connect it?

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From 300CE to SLK230K

Just a followup.
So if the main cause of the fuel accumulator to go bad is a broken diaphram won't a leak on the return end signal this?