Overfuelling problem

[RangieMatt]

Hi there,

I have a problem with my Range Rover. It's a 1991 3.9 EFI V8. Just before christmas, I went to start it, it's been missing occasionally just after starting until you rev it, but it stumbled badly, firing on maybe 4 or 5 cylinders, and died. I went to restart it, and had no joy.

After recharging the battery fully, it still wouldn't start, it would crank merrily, and only occasionally fire briefly. It also STINKS of petrol. There's new fuel in it, the pump is priming, and there's fuel getting to the engine fine.

I then treat it to a set of new plugs. It sprang into life straight away, albeit with a plume of black smoke or two from the back. It then ran ok, but smelt very strongly of petrol. I took it for a drive, and 4 miles from my house, came to a village, and needed to take a junction. It cut out straight away as soon as I dipped the clutch, the revs dropped off right past idle and the engine died. It restarts ok, but will not idle, the rev's simply die off.

Also, I've now done approx 25 miles since the new plugs went in, and it's misfiring badly again, even on normal running, not just idling, the last time I took it out for a quick spin, it arrived back running on 6 cylinders.

What should I try next? What could be causing over-fuelling? I definitely think the cause of the stalling is simply too much fuel going in.

[5000SE]

Hi there,

I have a problem with my Range Rover. It's a 1991 3.9 EFI V8. Just before christmas, I went to start it, it's been missing occasionally just after starting until you rev it, but it stumbled badly, firing on maybe 4 or 5 cylinders, and died. I went to restart it, and had no joy.

After recharging the battery fully, it still wouldn't start, it would crank merrily, and only occasionally fire briefly. It also STINKS of petrol. There's new fuel in it, the pump is priming, and there's fuel getting to the engine fine.

I then treat it to a set of new plugs. It sprang into life straight away, albeit with a plume of black smoke or two from the back. It then ran ok, but smelt very strongly of petrol. I took it for a drive, and 4 miles from my house, came to a village, and needed to take a junction. It cut out straight away as soon as I dipped the clutch, the revs dropped off right past idle and the engine died. It restarts ok, but will not idle, the rev's simply die off.

Also, I've now done approx 25 miles since the new plugs went in, and it's misfiring badly again, even on normal running, not just idling, the last time I took it out for a quick spin, it arrived back running on 6 cylinders.

What should I try next? What could be causing over-fuelling? I definitely think the cause of the stalling is simply too much fuel going in.

Sounds like it could be the temp sensor, or a break in the loom to the temp sensor - making the engine think it's clock cold, and so over-fuelling. I had the same symptoms.

[RangieMatt]

that makes sense, I think I'll get that changed next then. Thanks for the advice, I'll let you know how I get on with it.

[5000SE]

Before replacing 'on spec', you could test it:

Deg C Ohms
0 5900
20 2500
40 1180
60 600
80 330

Cold - 2000-6000 ohms. Hot about 300 ohms.
Can bridge with .5 watt 180-330 ohm resistor

[RangieMatt]

ah that's great, thanks a lot for your help

[kiwicar]

Just a quick addition, it could be in "limp home mode" this occours when the ECU thinks it is missing a sensor, you need to reset the ECU by disconnecting the battery and reconnecting it after you have fixed the fault otherwise it keeps overfueling the engine.
Best regards
Mike

[RangieMatt]

worst case possible scenario has happened, I was as careful as dammit, and I'm still 100% positive it didn't go in cross threaded, but the thread has stripped in the inlet manifold for the CTS. It's almost completely in, possibly just under 1mm to go, and it just turns, I can't get it any further in, or out.

Bah humbug.

[JC.]

Whip it out and have a look.
IF it has stripped you can try to helicoil the manifold. You might be lucky and have stripped the threads on the sensor.
I say lucky... i meant less unlucky

[RangieMatt]

yea, will do, just one of those things I guess. The thing that's suprised me is I'm 100% positive I was screwing it in dead straight, I'm not the most skilled mechanic in the world, but I'm not daft either, I can tell when something cross threaded, and it's definitely not, it's sitting flat even now, just it won't come out, or go further in.