Topic

Hello,
Because of Covid, my 2000 MGF was garaged and inaccessible. The battery went flat. Four weeks ago, I replaced the battery. The fuel pump primed and the engine started immediately and ran for about 3 seconds before just stopping. It won’t start again unless one waits for the engine management ECU to reset and then allow the fuel pump to prime again. Then same thing, engine starts immediately and then stops after 3 seconds. This can be done repeatedly. I decided to replace the crank sensor. No resolution. If pump primes, engine starts immediately and then stops.
I then used my PSCAN to check for any engine management errors. None with ignition on, but engine not running. No errors detected either when the engine ran for it’s three seconds. The crank sensor ‘synched’ like it should when engine ran briefly.
No error codes for alarm system/immobiliser either. System is MEMS 1.9
But for the Airbag system, I got the error code in the subject of this message. Foolishly, I did not bother to check whether the SRS warning light was staying illuminated. But I imagine that it was.

Upshot - would this fault in the airbag system prevent the engine from running except for the three seconds when fuel pump ore-primes?
And if so, where would this fault be located? Would it be the driver’s airbag (car is LHD German spec)? Or is there a fuse or relay that could be causing the excessive impedance?
Any help would be most welcome.
Frustrated in Vancouver, Canada

Your SRS error is related to left hand side pretensioner. First thing I would look is weather or not SRS light is iluminated or not in order to see if this is historical error, or present one. If present one I would start with connector to the pretensioner under your seat. Be warned that you should disconnect your battery when working on anything related to SRS to prevent accidental deployment of airbag.
This error is related to high resistance in the circuit from SRS ECU to the left hand side pretensioner. High resistance is usualy problem of bad contact in the connecotr, but it can be related to pretensioner itself or bar wiring to the pretensioner.

However this eror has nothing to do with your engine starting and running only 3 seconds.

Your alarm is disarmed is it?

Regarding your engine fault, this also could be problem of management multirelay (consist of four relays together among which one is responsible for fuel pump).

Sounds like a fault on the fuel pump. Could be a faulty electrical connection that is shaken loose by the engine running.

Roverlike,
Thank you for your response. Replacing the four relay multi relay pack mounted on the engine management system to the left of the engine (when facing forward from the rear of the car) is the first thing that I did. That did not resolve the problem either.
If the airbag fault system is not what is causing the engine not to run, I am beginning to suspect that it may be the engine ECU itself.

David, I agree that it is a fuel issue. The engine consistently fires and runs for the three seconds whenever the engine ECU instructs the fuel pump to prime. But once the engine starts under these circumstances, it quits as if it is getting no fuel. The engine will not start and run when cranking the engine unless one gives enough time for the engine ECU to reset and instruct the fuel pump to prime the system again.

I am more concerned about what is causing the engine not to run (that is, why no fuel is being delivered except when the ECU instructs the fuel pump to prime).
After replacing the multi relay pack, I thought that it might be the crank sensor not sending a signal back to the engine ECU. But that has not resolved the issue either.

Any other ideas? Would it be worth having the engine ECU checked? Again, PSCAN showed no error codes for the system. But that might not mean anything.
Jess

Roverlike,
Thank you for your response. Replacing the four relay multi relay pack mounted on the engine management system to the left of the engine (when facing forward from the rear of the car) is the first thing that I did. That did not resolve the problem either.
If the airbag fault system is not what is causing the engine not to run, I am beginning to suspect that it may be the engine ECU itself.

David, I agree that it is a fuel issue. The engine consistently fires and runs for the three seconds whenever the engine ECU instructs the fuel pump to prime. But once the engine starts under these circumstances, it quits as if it is getting no fuel. The engine will not start and run when cranking the engine unless one gives enough time for the engine ECU to reset and instruct the fuel pump to prime the system again.

I am more concerned about what is causing the engine not to run (that is, why no fuel is being delivered except when the ECU instructs the fuel pump to prime).
After replacing the multi relay pack, I thought that it might be the crank sensor not sending a signal back to the engine ECU. But that has not resolved the issue either.

Any other ideas? Would it be worth having the engine ECU checked? Again, PSCAN showed no error codes for the system. But that might not mean anything.
Jess

I do not know that engine ECU makes any resetting.

What I am thinking is to make check of two things: fuses, maybe replace them for new ones (for fuel pump) and ignition switch conector if it has good contact and not braking contact at some point.

I would check the live and earth at the fuel pump. You can access these by removing the carpet and soundproofing on the shelf behind the seats. There is a circular access panel there. Check that the pump has a good feed and earth when the engine runs and then stops. If it does suspect the fuel pump.

Hello David,
That’s my next stop. If that all checks out, I am going to jump the power directly to the pump from the line into the inertia switch to see if the engine will then run continuously. If it does, there is something going on that is making the ECU instruct the fuel pump not to operate except for initial priming.
Jess

Fuel filter often gets overlooked whan servicing, this could lead to fuel starvation, worth a shot and easily replaced.

Thanks gloscs,
I’ve replaced this too. What is odd is that when the pump pre-primes, the engine immediately starts with no effort and then stops after 3 seconds due to what seems to be an absence of fuel.
Jess

Can you disconnect a fuel line to confirm this?

Unfortunately, not where the car is garaged. It is located in an underground garage in a block of flats. If the engine does not run by jumping the power directly from the inertia switch to the fuel pump (with an inline toggle switch in my jump wire so I can cut the power), I will arrange to tow it to someplace where I can run the pump with the fuel line disconnected.