MG Maestro not firing

[kodachromeII]

Hi, further to my previous thread, my maestro has now died, the car has been running irratic once up to temp. So far i have renewed the coil, leads, plugs, cap, arm, temp sensor ( nr the thermostat ) and injectors. Tonight after a test drive the car wont start. The injector prime noise is evident. The car wont fire, i've swapped the coil for the original coil and still nothing.
Test lamp indicates no 12v supply on the coil?

Can anyone point me in the right direction...

Andy

[G Force]

Hi,Test lamp indicates no 12v supply on the coil?

Can anyone point me in the right direction...

Andy

Hello Andy, if you have no supply to the coil with ignition on measured with a test lamp, disconnect the coil + terminal and recheck just to eliminate the possibility of a short on the coil or amplifier (inside ignition ecu).

If you confirm no voltage at coil + you will have to trace the ignition supply back to the switch. Pay attention to any immobiliser that you might have fitted.

[kodachromeII]

Hi, rechecked the supply to the coil, i do have 12 volts, must of had a bad earth when testing. Currently the car is not firing, with strong petrol smell when cranking the car, thus i'm lacking a spark!!
BTW, no immobiliser fitted...

[Russ]

What leads did you use? I fitted a non genuine king lead a bit back and car ran terrible. Fitted genuine unipart leads and it sorted it out

[kodachromeII]

Hi, bosch leads were fitted.. Swapped out cheapo ones, made no difference to original fault which was irratic running. Car not firing at all since yesterday. Old leads refitted, still not firing :confused:

[Roperman]

Is the "button" in the dizzy cap making contact with the rotor arm? I've had a new one in the past that didn't and it took me a while to realise why it wouldn't start. Thought i'd put the leads back the wrong way.

[G Force]

It is not unknown for new rotor arms to be faulty. The test I described in your other post would confirm if faulty or not.

Do you definitely have no spark?

[kodachromeII]

It is not unknown for new rotor arms to be faulty. The test I described in your other post would confirm if faulty or not.

Do you definitely have no spark?

You were spot on, new Genuine Rover Part rota arm was defective.

Car now firing ok, original fault still present.

Once up to temp car is very lumpy, the car runs perfectly until the engine gets warm...

Do i have a defective sensor?

[G Force]

Once up to temp car is very lumpy, the car runs perfectly until the engine gets warm...

Do i have a defective sensor?

If the temperature gauge is working correctly then you can more or less be sure the temperature sensor is ok.

Thinking back to the conditions when you said the problem started, Is there any possibility that water has got ointo the tank? Maybe a corroded filler neck / breather tube etc.

Water contamination of the fuel will have a more noticable effect on performance when the engine is up to temp.

Check for air leaks in the crankcase breather hoses / vacuum pipes, manifold gasket etc. Double check the spark plug gaps are no less than 0.035in. Too narrow plug gaps cause misfiring at idle and light throttle.

If not maybe it is time to go back to basics and check the cam timing, valve clearances and individual cylinder compressions?

[kodachromeII]

Thanks G Force, new temp sensor fitted ( the one nr the thermostat housing ).
I have missing on idle, but its only intermitten, again its missing once warm.

When the fault does occur, its like i'm on kangeroo juice, then the car sorts its self out for a short while then it starting missing again.. :giveup:

I've managed to go through two full tanks of petrol since the problem started, is there any mileage in me emptying the fuel tank?

Sorry if this is a stupid question, but which one is the crankcase breather hose?

[G Force]

When the fault does occur, its like i'm on kangeroo juice, then the car sorts its self out for a short while then it starting missing again.. :giveup:

If when the car starts to kangaroo, the rev counter jumps and bounces up and down erratically, there is a fault on the low tension side of the ignition system. You would then need to check the crankshaft sensor plug for a poor connection, moisture contamination, corrosion, or a break in the wiring. Disconnect the crank sensor plug and pull back its rubber boot to thoroughly inspect the wiring. Check the connections on the coil are tight. Check the connections on the programmed ignition ecu. If you fail to find a fault the crankshaft sensor or ecu could be faulty.


I've managed to go through two full tanks of petrol since the problem started, is there any mileage in me emptying the fuel tank?

If the rev counter registers as you would expect when the car kangaroos then yes it is worth draining the tank and inspecting the fuel. If you drain it into a clean container and let it stand overnight, any water in the fuel will be visible at the bottom of the container. If you carefully siphon the fuel above the water into another clean container and let that stand, when you get to the stage where no water is visible you can reuse the remainder.

Sorry if this is a stupid question, but which one is the crankcase breather hose?

Crankcase breather hoses, one comes from the oil separator on the front of the sump & leads to a tee-piece, one pipe from oil filler cap to tee-piece. Tee-piece to the throttle body. One smaller hose runs directly from the oil separator to the throttle body. On some models a small pipe runs from the oil filler tube to either the throttle body intake hose or the top of the air filter box.

[kodachromeII]

Once again, many thanks,

Renewed crankshaft sensor, all wiring to the sensor, including old senor was in excellent condition.

EDIT,

Update, wire feeding oil sensor is bare, appears to have been rubbing on shaft, also connector under rubber boot rotten and wet !!
Fitted new sensor ( luckily i purchased one last week, but omitted to check the damm thing ), the cars tickover from cold is now very high. Car now appears to run fine once up to temp.

[G Force]

Update, wire feeding oil sensor is bare, appears to have been rubbing on shaft, also connector under rubber boot rotten and wet !!
Fitted new sensor

Hi kodachromeII.

Unlike some of the BL and Rover cars the oil pressure switch circuit is not used in the fuel pump control circiut on Maestro EFI cars, so a fault in this area can't have any direct influence on engine management.

Hopefully if you changed the crank sensor recently, that could have sorted it :)

[kodachromeII]

I'll take the car out for a long test drive on Friday, fault was there after crank sensor changed, hence i feel i'm no further forward.
Can someone recommend somewhere we i can take the car and ( hopefully )
have the problem located/fixed.
I'm in Surrey.

Thanks

Andy

[kodachromeII]

see post below..

[kodachromeII]

If the rev counter registers as you would expect when the car kangaroos then yes it is worth draining the tank and inspecting the fuel. If you drain it into a clean container and let it stand overnight, any water in the fuel will be visible at the bottom of the container. If you carefully siphon the fuel above the water into another clean container and let that stand, when you get to the stage where no water is visible you can reuse the remainder.


G Force, sincere thanks, although i have not yet drained the tank, the smaller pipe leading to the tank near the filler cap has completely rotted, thus i'm assuming surface spray is going directly into the fuel tank, recent test drives have been in the wet, only adding to any further water contamination in the tank...

Now i need to source the down pipe etc..

Once again thank you...

Andy

[Russ]

ignore my responce on your pipe wanted thread, can you not cut out the rotted section of the breather pipe and replace it with hose?

[kodachromeII]

http://www.maestro.org.uk/forums/picture.php?albumid=226&pictureid=2036

Russ, my only option is a complete replacement new/used filler pipe, the smaller pipe has rotted on the neck of the filler pipe.

Thanks to everyone, for the replies amd PMs, I've now attached a photo of my existing filler pipe!!!

[Russ]

If you've no luck finding a replacement you could try plastic steel, its supposed to be resistant to petrol and oil .Once it goes off after about 20min it can be drilled, tapped sanded etc. So you could open the hole out cut the small pipe off, fill with plastic steel then drill and tap a hole for a new union for a hose to connect with the good small pipe