[batmanandbobbin]

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

 

[parad0x_i]

Sorry i don't know the location of your FPR.. mine is behind the battery

What i would suggest is that there's little in them that can 'be dying' as such..
It will either work or not..

What might be causing it is corrosion around the pins.. dry joint inside or a loose connection or fuse..

I took mine apart and removed any dry solder joints and then re-soldered them..
New FPR's are expensive..

 

[batmanandbobbin]

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?

 

[parad0x_i]

I see now that the FPR for your model is a simple relay.. hence the price..
I was quoted £92 +vat for my 260E.. which is why i chose to repair it..

I did a google to try to find out the location of yours but drew a blank..

Good luck..

 

[redlaser]

See the link to Autohausaz below for a pic of the FPR...probably near your fuse box.


Your Parts Search Returned 1 Part(s)

 

[batmanandbobbin]

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

 

[augapfel]

On every EFI car I've ever worked on, the fuel pump runs for a few seconds as soon as the key is turned to run. This is to ensure that the EFI system is adequately pressurized for the injectors to spray prperly.
The pump keeps running so long as the engine is cranking. If the key is released from cranking and the engine hasn't started, the pump is shut off after ablut 2 seconds. If the ECU loses the crankshaft position signal while the engine is running, the fuel pump is shut off. This last one is to prevent the pump from emptying the tank following a crash where a fuel line has ruptured.
Can't help with location since my experience (at least in that area) is with the early 124s. Under the hood, near the battery is my best guess, though.

 

[parad0x_i]

Same here.. fuel pump should run a few seconds for each ignition key turn (from fully off). If not then it's not getting any power.. Check all relays in the relay box are tightly pushed down and all fuses are ok..
Check also the 3 pin connector (Black plastic rectangle about 4cm x 1cm) which is situated on the bulkhead in front of the battery. It pulls apart. Centre connection is starter switch wire and the other 2 are power leads - all 3 activated by the ignition switch..

I think you'll find your Fuel Pump Relay in the main relay box behind the fusebox.. (next to brake servo) as it's a very simple small non-electronic one