Fuel Pump Relay in 1995 E320 Wagon

12263 Views 7 Replies 4 Participants Last post by parad0x_i, Apr 17, 2009

batmanandbobbin

Discussion Starter · Apr 9, 2009

Hi--

My fuel pump is sometimes not turning on when I turn the key before starting the engine. The pump sounds fine when it runs, but it sounds like the fuel pump relay is dying. I used to have this problem on volvos that I drove and it was easy to replace the fuel pump relay in the older volvos.

My question is: where is the fuel pump relay on my car? The service CD's show that it is in the rear compartment of the sedans, but I don't see a location for the wagons. I've read a lot of posts claiming that the fuel pump relay is under the rear seat, behind the battery, or that the fuel pump relay is part of the OVP and that there is no separate relay.

The service CD's show a distinctly separate device called the fuel pump relay, so I believe that there must be one somewhere. Can anyone advise on where to find the relay in my '95 E320 Wagon?

--James

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batmanandbobbin

Discussion Starter · #3 · Apr 10, 2009

Relay

Thanks for the reply. It's definitely an intermittent connection. Sometimes, the inside of the relays don't energize properly all the time and they don't close the circuit. Once they close the circuit, though, there's usually no problem.

I have a new relay on the way (it was only $22.00 from Rusty) and a new fuel pressure regulator. I just wish I knew where to pop in the new relay.

Anyone else know where the fuel pump relay is?

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batmanandbobbin

Discussion Starter · #6 · Apr 13, 2009

fuel pump behavior on 94-95 E320's and no starting

Ok--

I think that I found the fuel pump relay (according to a diagram from the service cd's). Haven't verified it yet, but it should be behind the battery near the main wiring harness. Funny thing is that I don't remember seeing it there. I asked two parts guys and their M-B parts databases show it in the center of the engine compartment, but they couldn't really tell whether this meant under the hood or behind the dashboard.

I've got the relay and a new fuel pressure regulator on the way, so I hope that one or both of them will solve my starting problem.

Problem: Car will sometimes crank and crank and crank but it won't run. This used to happen only when the car/outside temp were warm, but it has recently started doing it intermittently in the mornings ('round 45-50 degrees).

If there is anyone who has a 94-95 E320 can you please let me know whether the fuel pump runs for a few seconds every time you turn the key to the running position before engaging the starter? Mine only runs after the car has been sitting awhile, so I don't know whether it is supposed to run each time the key is turned to the running position.

If the relay and the fuel pressure regulator don't solve it, I'll replace the fuel pump check valve next along with a new fuel filter (replaced only 5,000 miles ago).

If still no success what next? Temp sensor? Crankshaft position sensor? Camshaft position sensor?

Any more ideas?

--James

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