engine stalls after cold start

Pieter Schmidt

New Member
Hello everybody,
I am suddenly experiencing trouble with the cold start. The car starts with the choke open and after a minute or so the revs drop and the engine stalls and stops. The only way to prevent that is to keep giving gas until the engine warms up and then it runs ok on idle speed. As far is I can see there is nothing wrong with the choke assembly (SU HIF6). Can anyone advise me on what to do about this?

Pieter
 
Is the secondary (fast) idle set correctly or is is simply running rich? The choke is designed so it can go back in partially and hold the throttle open slightly while not running at full enrichment. Mine literally only needs to run rich for a few seconds to start.
 
Important thing is that fast idle should be set with the screw pointing at the mark on the choke cam (different on our HIF6, but same meaning). If its ok once warmed up, then the choke Orings are probably OK, but watch for wetness around the choke cam and shaft.
 
Hello everybody,
I am suddenly experiencing trouble with the cold start. The car starts with the choke open and after a minute or so the revs drop and the engine stalls and stops. The only way to prevent that is to keep giving gas until the engine warms up and then it runs ok on idle speed. As far is I can see there is nothing wrong with the choke assembly (SU HIF6). Can anyone advise me on what to do about this?

Pieter

Hmmmm you own a P6B, mine always did that for the first 2 to 4 KM driving sometimes even further, no matter what I did to the SU carbs.
Eventually I eliminated the problem by going to a 4 barrel Weber carb. Others have fitted injection, that also solves the problem.
Possibly if you run it run rich but then you MPG will suffer.
The SU are a terrible solution to the drivability of the V8 and I am guessing that whomever recommended there fitment had a perverse sense of humour, hardly the carb you want on an executive performance car.

Graeme
 
HMMMM. Have never heard this sort of criticism of the 2" SU on a P5 3litre. Never had a problem like this on my TC2000 with HD8s - they only needed needle and seats and jets/diaphragms every few years. Same for P4s with either single or twin SUs.
 
HMMMM. Have never heard this sort of criticism of the 2" SU on a P5 3litre. Never had a problem like this on my TC2000 with HD8s - they only needed needle and seats and jets/diaphragms every few years. Same for P4s with either single or twin SUs.

We had a P5 3.0 litre also back in the 70's and as you say never a problem with the SU's at all.
Not had a P4 or the 2.0 litre but I expect as you say there would be few issues.
It's possibly due to having the carbs set a little lean as I used to achieve up to 27 MPG on longer runs.
 
Back in the day I had TC, put a CDI ignition on it, won a club economy run, based on mpg x weight - ton/mpg.
 
Hmmm, from my experience, the SU is an excellent carburettor for the Rover V8. With my 3.5 litre engine, I did have to make liberal use of the choke, especially during cold weather. As the engine warmed I could slowly put the choke in, but it was across a good few minutes. My 4.6 litre V8 is a totally different story. I can put the choke fully in within a few seconds from starting, the engine will idle perfectly, and I can drive straight off without any hesitation, and the engine has returned 31mpg!

I think the factory needles and settings are on the lean side for the 3.5, whereas my 4.6 uses much richer needles, changed float settings, and butterflies without poppet valves.

Ron.
 
Is the secondary (fast) idle set correctly or is is simply running rich? The choke is designed so it can go back in partially and hold the throttle open slightly while not running at full enrichment. Mine literally only needs to run rich for a few seconds to start.

Thanks for all your tips. The video is helpfull, only now I understand how the choke works!
It starts to stall after only half a minute or so, when the engine is still cold. Before this problem, I always gradually closed the choke after a few miles running, I couldn't close it after a few seconds. And if I close it now after a few seconds, it dies immediately, which suggest to me that it is not running too rich.
I will have another close look and see if adjusting the fast idle speed helps.

Pieter
 
Hmmm, from my experience, the SU is an excellent carburettor for the Rover V8. With my 3.5 litre engine, I did have to make liberal use of the choke, especially during cold weather. As the engine warmed I could slowly put the choke in, but it was across a good few minutes. My 4.6 litre V8 is a totally different story. I can put the choke fully in within a few seconds from starting, the engine will idle perfectly, and I can drive straight off without any hesitation, and the engine has returned 31mpg!

I think the factory needles and settings are on the lean side for the 3.5, whereas my 4.6 uses much richer needles, changed float settings, and butterflies without poppet valves.

Ron.

Yeah that's how my one was too, the choke was essential for the first 3 or 4 Kms.
Astounding mpg Ron but I don't doubt it for a second.
Would love a 4.6 in mine with mapped injection.
 
@Pieter Schmidt, perhaps you are simply releasing the choke too soon? If you pull the choke and wait for the orange choke warning light on the dash to illuminate before releasing it, does the engine then still stall without extra application of throttle?
I should say I don't know if the four cylinder P6s behave in the same way. I can only comment on the 3500 version.
 
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