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Marty
Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53165
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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Need help with my 1995 e32 mercedes wagon

Customer Question

need help with my 1995 e32 mercedes wagon
Submitted: 11 months ago.
Category: Mercedes
Customer: replied 11 months ago.
Expert:  Marty replied 11 months ago.

Hi, my name is***** can I help you with?

Customer: replied 11 months ago.
after our car cut out while going around a corner then wont start, we replaced the fuel filter and both fuel pumps, and spark plugs. car wont start. cranks but wont start. check fuel pressure on rail. no fuel pressure. took fuel line off after first fuel pump no fuel. fuel in tank. fuel getting to the first fuel pump and nothing after that. took fuel pumps out tested they worked. put back in
Customer: replied 11 months ago.
are u still there/
Expert:  Marty replied 11 months ago.

Hi, sorry for the trouble with the site this morning. If both pumps work but you don't get any fuel pressure the problem would have to be inadequate flow from the tank to the pump. You might have flow initially but it may be slowing down to a trickle as the pump tries to draw fuel from the tank. I'd have to suggest that you check the screen in the tank and see if it is plugged.

Customer: replied 11 months ago.
ok ill check it
Expert:  Marty replied 11 months ago.

Sounds good. Let me know how you make out.

Customer: replied 11 months ago.
Hi marty, i didnt check the screen but when i took the fuel pump off to check it. for power and function fuel was pouring out of the line from gas tank. no restriction in fuel flow so i dont think screen is problem.
Expert:  Marty replied 11 months ago.

If the fuel poured out for awhile the problem shouldn't be the screen. If that is the case then the problem would have to be with one of the pumps. I'm assuming that your pressure gauge is working properly. You should have 52 psi fuel pressure at the fuel rail when cranking the motor.

Customer: replied 11 months ago.
I took the new pumps off and tested them with with twelve volts and they pumped.?
Expert:  Marty replied 11 months ago.

That's not really a good test. You need to measure the pressure at the fuel rail. If you don't have 52 psi when cranking one or both of the pumps must be bad.

Customer: replied 11 months ago.
when i turn on key both pumps run? and they are brand new webers? how could they be bad?
Expert:  Marty replied 11 months ago.

Weber is not the OEM pump for that car. I would question their compatibility. Bosch pumps are the OEM pump. I would not trust anything but Bosch.

Customer: replied 11 months ago.
do you think if i switched to bosch pumps that would solve the problem?
Expert:  Marty replied 11 months ago.

If you have fuel from the tank to the first pump but you are not getting any fuel pressure I would have to say that the pumps are not suitable for this application or they are wired backwards. Switching to the OEM pump should solve the problem. Check your wires first and make sure you connected them properly. The brown wires go to the negative terminal on the pumps.

Customer: replied 11 months ago.
Hi Marty,
Put the working bosch pump back in the first fuel pump postion closest to fuel tank and same thing. pump goes on no fuel past pump. check wiring hooked up correctly. I think Ill go back to screen in fuel tank since I dont think it is the fuel pump itself. how do you remove the screen? also i dont know if this has anything to do with it, but the gas gauge reads 2/3 full when you fill up. i put some more gas in it just to make sure there was fuel in it?
Expert:  Marty replied 11 months ago.

It's got to be a problem with the flow from the tank. The screen in the bottom of the fuel tank unscrews but it can be difficult to access. Follow the main hose up to the tank and unscrew the hose and the screen. If you just pull the main hose to the first pump you should be able to drain the entire tank before you remove the screen. If you find that the flow from the tank slows down to a trickle it would indicate a plugged screen but if the tank drains fast from the hose the problem has to be with the fuel pumps. If the gauge is not reading correctly I'd try adding at least 5 gallons of fuel to the tank and see if it will pump fuel before I drained the tank.

Expert:  Marty replied 11 months ago.

Hi, I'm just following up with you on the Mercedes. Did you ever get it running?

Marty

Customer: replied 11 months ago.
but idles rough.smoother @ 2500rpm?
Expert:  Marty replied 11 months ago.

Great! What turned out to be the problem? If my information was helpful I would appreciate it if you would click on a rating for my service as this is the only way that I can receive credit from the website.