Nissan Patrol 4x4 (Africa)

Morning, last night driving home my lorrie had a suuden loss of RPM at robots, from 750 to about 300 and idling rather erratic
I have replaced the bogey cords about 2weeks ago

I know very little about petrol motors, but could that not be a carb problem, possibly dirty jet or sticking butterfly.

PETER CONNAN !!!!...... look here.....hahaha

Jules wrote: ↑30 Jan 2019 07:09 Morning, last night driving home my lorrie had a suuden loss of RPM at robots, from 750 to about 300 and idling rather erratic
I have replaced the bogey cords about 2weeks ago

Sounds like the carburetor is dirty. I had exactly that on Shorty.

All traffic and no open roads makes Carburetor a dull boy.

Mr Connan taught me a bush trick that sorted it out.
Open up die air filter and try to suffocate the engine with a towel or similar, while someone else is revving the car up to about 2500.
As the engine suffocates, your partner on the pedal need to push down further to try and keep the revs up.
The engine should still suffocate if you seal it off well enough.
Do this two or three times.

Carburetor should revert to idling smoothly thereafter.

ricster wrote: ↑30 Jan 2019 08:28 I know very little about petrol motors, but could that not be a carb problem, possibly dirty jet or sticking butterfly.

PETER CONNAN !!!!...... look here.....hahaha

Ek sal bietjie Doom spuit vir daai bottervlieg

my carburator is so paar maande terug ge refurbish, Peter het nog vir my die kit gestuur , so surely it should be rather clean ???

Not sure.... but if it's got wheels and wears a bra, there is a possibility it will give you hassles.....hahahahahaha..... just kidding

Mine sometimes does this when the tank is close to empty.

I would say:
1) Check that all those new plug leads are well and firmly plugged in.
2) Check all the vacuum hoses are plugged in and don't have holes.
3) Check the petrol filter.
4) Strangle it as Alex described.

... what about the distributor?

Alex, my list was not intended to be a fully comprehensive and exhaustive list of everything that could cause such a problem, merely the most likely causes.

I guess the distributor could cause something like this, either if the locking screw has come loose and the timing has drifted off, or if something has gone wrong with the vacuum advance?

But I suspect that, based on my limited experience:
1) If one or two cylinders are "losing spark", the engine might struggle to idle smoothly, and since the plug leads were recently replaced, this could be the likeliest option.
2) Failing that, I think the most likely following cause would be a fuel supply issue. This could be from a number of causes.
3) Pretty much everything else I can think off (including the two distributor issues above) would most likely cause symptoms throughout the rev range?

Got it.

In my case the idling was only erratic at low revs, which is what Jules's case also sounds like.
And then it seems most likely either fuel supply or spark, as you say.