havok13154

I have a 2001 Mercedes CLK55 AMG and when I try to start the car I can hear the starter going but it doesn't start, the 2nd time I try it sounds like it is going to start and then sounds better then starts(like it is trying to get fuel but can't and then it gets enough and starts). car runs fine after. if I turn it off and start it right away it starts. if I wait 30 sec it take a few sec to start. if it sits for 15 minutes it take 2 cycles to start. When the car is running it is fine. I floor it and it pulls hard. i replaced the fuel filter less then 10k ago and all 16 plugs 15k or so ago.

What do you think could be the problem?

Ausmbtech

Sounds like the fuel pressure is dropping after shut down, check your fuel pressure after shut down with a gauge. If it drops quickly (by the sounds of it, most likely) I'd be looking at either an internal leak in the fuel filter (pressure regulator) or the check valve in the fuel pump (replace whole pump).

havok13154

I'll check that tomorrow. maybe auto zone has a rent a tool for that. I replaced the battery as it said replace when it was tested. I have 2 battery (car audio) so i never notice the stock one died. didn't fix it

VividRacing

If it's cranking hard, I'd rule starter/battery out of it. I don't know if a parts store will have a rental tool, but even if they don't all you need is an inline fuel pressure gauge and a short piece of fuel line so you won't be spending too much.

havok13154

I picked up a new fuel pump and on the way home when i hit the gas it bogged down when i floored it. once it get to 2000 rpm it is like i am giving it a little throttle when flooring it. i replaced the fuel pump and still have the same problem. still no engine light. I replaced the MAF sensor 2 months ago, could it of went bad again? it didn't act this way when the maf died and it tossed a code. i pluged in a standard OB2 and no codes.

smickster

I have a 1998 E430 Sport with 201,000 miles, (I Love This Car!) and am having a problem very similar to havok13154. I'm also having starting issues, especially if the engine is still hot. The idle is also a little rough and I have code P0170 and the Check Engine light.

I hooked up a fuel pressure gauge to the Schraeder valve on the passenger side manifold and read ~40 psi at idle. When I revved the engine the pressure dropped to ~30psi. I understand that the fuel pump is rated for 110psi. I'm guessing that the fuel filter/regulator may be the issue and will be checking the fuel pressure upstream and downstream of it.

Does anyone know what the fuel pressure at the manifold should be?

Thanks for your help! This forum has helped me MANY times.

havok13154

start your own thread please, i am trying to fix this issue. you ahve a engine light i dont, differnt problem.

going to try the throttle position sensor I think.

havok13154

I have replaced the MAF, Fuel Pump, battery. unhooked both manifolds at the cats to test if the cats where clogged. trying TPS, need star diag badly wish i had one.

grane

There is a Bulletin on fuel system replacement due to ethanol corrosion that I am trying to find. The symptoms described match.

Anybody have access to that TSB?

smickster

An important piece of information that helped me diagnose my problem is that the fuel filter is also a pressure regulator and a check valve to maintain fuel system pressure. I had just replaced my pump and fuel filter 3 months ago and the filter went bad already. After changing the filter my hard-starting problems were gone.

havok13154

I replaced the TPS and still has the same problem. i just replaced the fuel filter but i am going to do it again.