Engine stalling / fuel pump? / W 463 / GE230 Short / 1992

Hi eyjolfsson,

I recently had a similar problem - although not a problem with starting.

I changed the distributor cap and rotor arm which I understand are common problems (although mine is a 300GE). That didn't make any difference.

Then I fitted a new fuel pump relay and that solved the problem straight away. The new relay only cost me £27 and I was a bit worried  as I found out after I'd ordered it that it was manufactured in China but it arrived (from England) really quickly and did work so at least I know that it was the fuel pump relay that was the problem so for £27 it was worth it.

No idea if they would ship to Iceland but in case it's of any help the place I got it from was

www.ebay.co.uk/itm/301765718976

It doesn't list this as suitable for a 230 so you might need to search again for the correct relay.

The usual culprits for your problem is Fuel related, Ignition related, Relays for either system or rubber hoses on the idle circuit in and around the inlet manifold area. 

Please enter you chassis number and if at hand, also the engine number as part of your Signature thread, it makes giving assistance more competent.

Given your model, engine dying and being intermittent suggests fuel pump relay or a induction issue. 

Distributor cap and rotor arm are not a common problem on your model only for the 300GE models. However, this does not mean omitting checking the components out and replace as necessary. 

Hopefully, you should be able to hear the fuel pump whirr for the first 5 seconds when the ignition is switched on - do not crank to start engine. The whirring sound only indicates the fuel relay and hence fuel pump is or should be working. This test does not indicate if fuel motor is working that it delivers fuel at the correct pressure or quantity. The fuel injection system runs at high pressure circa 3 bar (+/-).

Your mechanic needs to do a fuel flow and pressure test. With respect, I do not know if your are mechanically practical; these tests could be done without specialist tools required but carries health and safety issues therefore I am unable to expose either myself or the club to any liability issues resulting in litigation of any sort. 

The fuel flow and fuel pressure tests will rule out any issue on the fuel supply side. Next area to consider is the fuel pump relay, these can cause intermittent faults as you have inherited. If you can substitute your relay with another that is the only test you could do and see if the fault transfers to the donor vehicle of the relay one can be assured the relay is at fault. Those with electrical knowledge may be able to repair yours other than that it is a case of replace and see.

The final area to look for is false air leaks around the inlet manifold circuit. Check all rubber hose which could be part of the idle circuit for frailness or perishing as air sucked from these upsets the running fuel/air mixture. These hoses are difficult to see. Ask your mechanic to trace false air leaks is to spray aerosol Brake cleaner around the inlet manifold including the underside on a running engine. Should the engine tone alter or improve then there is air leak present. Aerosol propellant and brake cleaner are highly flammable! DO NOT spray near spark plugs, leads or any ignition components. Air can be sucked from injector seals, spray around this area to test.

All test being thoroughly carried out the only two remaining areas of fault could the distributor, ignition coil or ignition module. Earth point between the module and chassis is paramount for efficient running. Earthing of the ignition module is at the underside of the unit and there is a special grease to smear if this is to be taken off. My suggestion is to run a separate wire on the module mounting bolt and another point of earth on the body, if the engine runs better then of course invest in the special grease and clean the earth and module base and refit. The grease is a dealer part only.