Engine runs well but cuts out

[kobe]

I just got the engine running on my 1985 MG Maestro - not started for 20 years. It sounds really good but it only runs for about 30 seconds and then cuts out. It will start immediately but then does the same again. There is fuel getting to the injectors. I have cleaned the fuel tank, replaced the fuel filter, replaced the plugs, injectors cap and rotor arm.

Any suggestions gratefully received!

[charliecosworth]

Fuel Pump relays ???

[kobe]

Thanks. Will check tomorrow. Any other possibilities?

[Guest]

Oil pressure sender?

if Turbo, (possibly efi as well) low oil pressure reading causes fuel pump to cut out.

I would also check for dodgy connections to the fuel cut off behind the radio, and connections to fuel pump itself.

[kobe]

Thanks Mal. It is an EFI but will check it out. I did replace the pump and connections were ok.

[E_T_V]

Monitor the fuel pump voltage on priming (9 or 12v I can't remember)
Cranking (12v I think)
And then running (9v).

If you get no pump on running then it is usually a fuel pump relay fault (there are two on the nearside inner wing).

[ian drew]

On a turbo the pump runs with cranking of the starter even if the fuse is removed. This provides enough fuel in the carb to run for about 1 minute once the car has started.
If the same principle is in place on the EFi, there may be enough fuel pressure in the rail to allow it to run for 30 seconds.

So, check the fuel pump fuse, relay, inertia switch behind the radio.

Like ETV said, then check the voltage at the pump and see if the behavious is like I mentioned.

Ian

[kobe]

Thanks guys. Got it sorted. It was the pump relay. You were right!!!

[kobe]

I got excited too soon. I'm really no further forward.

We replaced the fuel pump the fuel relays, the fuel ecu, ignition ecu, the injectors, the plugs, the rotor arm and the distributor cap.

The car starts and runs fine for a few minutes it then starts to run 'lumpy' before cutting out. There is plenty of fuel to the fuel rail.

When the engine is starting to run badly, if you disconnect the two right hand injectors, it makes no difference. If you disconnect either of the other two the engine cuts out.

Any ideas before I lose all my hair??!!

[E_T_V]

Low fuel pressure from a duff pump or blocked fuel pick-up?

I think the EFI gets 12v to prime the pump and only 9v when running. Does the engine restart? If you turn the igntion off for 2 minutes and then try again does the engine start cleanly then? (If no to the first and yes to the second then it is likely to be a fuel issue)

[kobe]

Thanks. Will check it out.

[G Force]

Hi Kobe

I think you have made some progress because you say the car now runs for several minutes rather than only 30 seconds, is that correct?

If so there are so many faulty new rotor arms on the market these days I would suggest refitting the old rotor arm if possible and proceed from there.

[kobe]

The car running longer must have been due to the angle it was jacked up at!!! Just put 15 litres of petrol in it as a last resort and it runs fine. Thing was it already had 15 litres in it so I guess there must be something wrong in the tank. Don't believe how long we spent on this!!

Thanks for all the help and suggestions. At least I got a lot of new parts fitted and some spares. lol.

[Guest]

When the engine is starting to run badly, if you disconnect the two right hand injectors, it makes no difference. If you disconnect either of the other two the engine cuts out.

Have you swapped the injectors over to see if the effect reverses? If so, I'd say you have 2 duff injectors.