Non starter MG Maestro

[efi 2.0]

Hi, just looking for a few points to check for a non starting 89 F plate 2.0 efi mg maestro. When turning the ignition on the fuel pump does not run and there is no noise from the steeper motor . But we have 12v to the fuel pump relay. Plus the fuel pump will run if the relay if the[ blue pink wire] on relay is earthed. But not the stepper motor. Going to check the earth points , plus connections on loom. I am thinking bad earth or faulty efi ecu . Both relays replaced with new ones and fuel pump resistor working ok with correct resistance. Any points will be appreciated. The car just got harder to start, then just wouldn't start, but ran very well other wise . Thanks Alan.

[mgdavid]

Isolator switch? (near the floor behind the centre console).
Oil pressure switch? or the wires running to it?

[G Force]

Hi, just looking for a few points to check for a non starting 89 F plate 2.0 efi mg maestro. When turning the ignition on the fuel pump does not run and there is no noise from the steeper motor . But we have 12v to the fuel pump relay. Plus the fuel pump will run if the relay if the[ blue pink wire] on relay is earthed. .

Hi

have you got the correct bosch 5 pin relay fitted to the main relay? silver metal case?

do you mean the fuel pump will run if you earth brown pink wire on terminal 85 of the relay? that what should happen. this also proves the inertia switch is ok.

[efi 2.0]

Hi, sorry just checked and it is the pink brown ( terminal 85 ) on the fuel pump relay. Checked oil pressure switch connection was loose so cleaned that up. Not checked the earths yet.
Got working metal bosch relays, and new plastic relays. But still no starting of the car just yet.
Thanks Alan.

[efi 2.0]

Forgot to add ,there is a spark from the plugs when turning the engine over.

[G Force]

Not checked the earths yet.
Got working metal bosch relays, and new plastic relays. But still no starting of the car just yet.
Thanks Alan.

Hi Alan.

If nothing is found on the earths or the wiring loom you could be looking at your first suspicions of a faulty EFI ECU.

[efi 2.0]

hello, Just checked the earth s ,for the efi ecu under dash and near bumper mount. All ok, so took ecu out . and checked continuity from efi multi plug back to relay all ok again. So going to find another efi Ecu part number (AUU 1313) ,are they all the same, or are the latter models ecu,s trimmed for unleaded! Let you know how we get on when find another ecu.
Thanks again Alan.

[Guest]

I'll second the correct relay query.

I had a problem on my montego back in about 89ish and ended up replacing the bosch relay with an identical looking one (as the bosch one disappeared during fault finding) I was stuck with a car that wouldn't start for months. Magically the bosch one turned up in my tool kit one day so I refitted it and the car started first time.

[efi 2.0]

Hi, we got the correct bosch metal relay, of a know working car. But the new ones are plastic cased. Will try another efi Ecu, as well . Looking at the case of the Ecu looks like water may have got to it someway a long the line. Once the cars running again can start getting ready for mot. Then back on the road again. Thanks Alan.

[G Force]

hello, Just checked the earth s ,for the efi ecu under dash and near bumper mount. All ok, so took ecu out . and checked continuity from efi multi plug back to relay all ok again. So going to find another efi Ecu part number (AUU 1313) ,are they all the same, or are the latter models ecu,s trimmed for unleaded! Let you know how we get on when find another ecu.
Thanks again Alan.

Hi Alan

You should replace the ECU with the correct part AUU1313, the 88MY part AUU1051 will work but I would definitely get the AUU1313 as it is correct and more reliable.

The EFI ECU's were not specifically different for unleaded fuel, it was the ignition ECU that needed to be changed.

[efi 2.0]

Thanks for that, think will try to get another Ecu (aux 1313). Or get the old one returned. Thanks for all your help so far. Alan

[efi 2.0]

Hi, Just tired another efi ecu. Still no joy, will have to recheck everything again ?.

[G Force]

Hi, Just tired another efi ecu. Still no joy, will have to recheck everything again ?.

Hi

Can you hear the main relay clicking when the ignition is turned on?

[efi 2.0]

Hi, don't get no clicks from main relay or fuel pump relay but, if we earth out main relay pin 85. Get clicking from main relay and stepper motor rattling, but no clicking from fuel pump relay or fuel pump priming. Does the main relay turn on the fuel pump relay!
The car ran fine power/ economy before , we had starting problems.
Thanks again Alan.

[G Force]

Hi, don't get no clicks from main relay or fuel pump relay but, if we earth out main relay pin 85. Get clicking from main relay and stepper motor rattling, but no clicking from fuel pump relay or fuel pump priming. Does the main relay turn on the fuel pump relay!
The car ran fine power/ economy before , we had starting problems.
Thanks again Alan.

Hi Alan

The EFI ECU controls the fuel pump relay, but the main relay has to be energised in order for the EFI ECU to operate the fuel pump relay.

Just to re-cap on some of your diagnostic work, you can operate the main relay by earthing the main relay pin 85 and also operate the fuel pump relay by earthing the fuel pump relay pin 85. You have also substituted the EFI ECU for a known good unit and have the correct relays fitted. You have checked the earth points on N/S bumper mount and under dash.

It all does suggest you may still have an EFI ECU earth problem. I would Clean up & Re-check both O/S and N/S bumper earth points, and make sure the ECU multi plug earth wires have continuity to earth.