Mystery Power/Acceleration Issue

C

Clive_687L

New Member
Apologies for the long post: I have a Rover 2000 SC. I was stopped at lights and white smoke poured from the middle bottom of the car then cleared. I drove on and two days later experienced loss of power when accelerating, the car buck jumping as the engine faltered before cutting out. It restarted and I nursed it home. I understand that a loss of acceleration and cutting out can be from carburettor or fuel pump issues (fuel starvation), vacuum leaks or ignition issues. I had noticed a smell of petrol and moisture on the top of the float bowl of the carb, so disassembled to check whether the pin of the valve and seat in the float bowl had failed. It had a metal coned shaped pin, which was slightly grooved, so assumed this could be getting stuck in the open or closed position and causing either starvation or flooding, which is what I guess happened when cutting out and I had the white smoke issue (fuel leaking on to the exhaust perhaps). I guess the valve is original as the new ones have a rubber pin. I tested the fuel pump by connecting the fuel supply pipe to a bottle and on cranking the car over it filled the bottle. I checked for vacuum leaks and found none. I bought a new valve and seat and installed it. I have driven the car around and around for a few days (not getting out of third) and had no issues other than once where there was a billow of white smoke behind me from the exhaust. I have pressed in the carb test pin and the engine returns to its normal idle speed. I have now gone further in my test drives and gone into 4th gear.

At nearly 45mph in 4th gear on an incline I experienced the lack of power/acceleration issue. I managed to keep it going, recovered and turned round to see if it would happen again. At the exact same point on the second trip it happened again. I avoided a stall and it recovered. I decided to see if it would happen again to confirm the pattern. It did the same thing at the exact same point at the same speed, in the same gear, accelerating up an incline. On the way home, going uphill he spluttered again and cut out. I rolled down the hill and pulled in, restarted and got home. I have revved him at full throttle to see if it cleared any blockages, but with the exact same result.
I decided to rule out the ignition coil by swapping it for a spare I have and exactly the same; same point, same conditions. So it is not the coil. I decided to check the spark plugs. They looked ok, but swapped the cylinders they were in to see if this would have an effect. I changed them over, 1 for 2 and 3 for 4, went out and exactly the same at the same point and conditions.The exahust may also be blowing in the centre section.

I find it weird that this happens only at the described point and the car drives fine apart from this. Does anyone have any thoughts as to what they may think the problem is. Thank you.
 
White smoke from the exhaust generally means you are burning coolant. I would start there and I suspect that you have a head gasket problem.
 
Ok, both above comments are valid. But the wet top of the float chambers sounds like a smoking gun (sorry, pun not intended). I would say the float chamber valve is sticking or not sealing correctly. That can give you a very rich mixture which can cause the engine to stall from flooding and an overflow onto the exhaust manifold/downpipe. If (fortunately) the petrol doesn’t ignite it can give you a white smoke. Was there a strong smell of fuel when it happened so you know?

Check float valve, also check float hasn’t sprung a leak and filled with fuel.
 
But not the actual float! Reduced power at a point on an upwards incline, repeatable, sounds a bit like fuel starvation, as in the pump is unable to supply enough volume when demand is high, OR, as mentioned above, mixture is going very rich somehow. I would check the pump for functioning properly, and the carb - bowl, jet, needle , and the fuel filter . With EFI you would have a spec for fuel delivery volume(cc/min) as well as pressure, but no such luck with a carb system. Is the float bowl in front of the carb body on a 2000? Is it vertical?
 
2 yrs ago I had a problem with fuel overflowing from Carbs (V8). I rest the needle valve level in both carbs. and then replaced float valve, all with no improvement, fuel still pouring out of carb. overflow. After talk with Burlem I was told that my floats (brown colour plastic) were 'old type' and should be changed to new type, white colour plastic. Changed floats and problem cured.
Nothing visible wrong with old brown floats, but new, white floats cured problem.
Do not know why, but it seemed that Burlem had seen this before.
 
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