e30 318i - No start

[Freegs]

Hi all,

I've got no-start issue on my stock 1992 e30 318i cabriolet (M40 8v with common oil feed issue/worn cam lobes). Brief timeline below -

• September 2020 I had it transported on a beavertail/car trailer from Cornwall to South Wales. It was running at this point but then crank but no start at the other end.
• 14/10/2020 Thought it could be bad/old fuel. Bought new 10ltr plastic jerry can and 10ltr shell v-power (longlife additivites) to attempt to move. Started then cut out, suspected spark/fuel issue.
• 17/10/2020 Changed spark plugs but determined it was fuel issue, not spark issue. Successfully moved it by bridging fuel relay (pins 30 which is red wire and 87 green/violet). Suspected crank position sensor or fuel relay issue.
• 16/09/2023 – Replaced fuel relay. Trial start with new relay, started but then immediately cut out. Suspected dirty fuel/clogged fuel filter.
• 04/11/2023 - Attempt to drain fuel at fuel filter by running pump by bridging 30/87 on fuel relay. No noise from pump, is pump dead? When I bridged pins, wire got very hot and it drained the (full) battery dead - all electrics dead.

Next plan is to recharge battery and attempt to start again to see if electric system is ok. With fuel filter removed, as I crank should this build fuel pressure and discharge fuel? I guess then fit new filter, stick 20ltr of fresh fuel in and try again.

I'm aware it's 30 years old and potential for loads of corrosion within fuel system.
Possible dead fuel pump.
Possible dead crank position sensor.

I also know it's a rusty old e30 with the least desirable engine and cam lobe wear but would nevertheless appreciate help/advice on next steps.

Thanks,

Tom

[BOR]

I think you need to eliminate the crank sensor as a cause, by replacing it.

The problem with a failing crank sensor is that it can be intermittent. If it fails while you are checking for a spark, you can be mislead into thinking you have an ignition problem etc.

After you have eliminated that as a cause, it might allow you to isolate the fuel pump or ignition as the real problem.

[pmorg4]

The above seems like sensible advice, especially if it's not expensive and access isn't too difficult.

I recall years ago I had a 3.0 V6 Vauxhall Omega which spontaneously cut out, then started up fine immediately afterwards. Another time it wouldn't start. Thankfully the crank sensor (actually poor routing of the wiring near hot exhaust and oil pipes) were a known weakness on those engines so it was my first suspect, and that solved the issue.

[Freegs]

Hi both,

Thanks for your replies. I've just ordered a new Crank Position Sensor and will get that fitted and report back.

Thanks,

Tom

[I-am-the-reverend]

It may be the crank sensor. They last 30 years or so - those old Bosch ones work until one day they just don't.

But, I'd power up the pump directly and see if it's any good. It could be seized.

The M40 engine has Motronic 1.3 or a derivative (second gen from late 1987) and there's not much to go wrong. From '91 they had 1.7 which isn't that different. No crank sensor and an old fashioned distributor cap and leads.

Iirc, the fuel pump relay, in common with LE Jetronic controls not just the pump but the injectors as well.