Jaguar XK140 cutting out when hot.
Discussion
Hi thought I'd ask a question for my Dad as he's having a few problems with his XK.
The car starts and runs fine then when it gets warm (or we hit traffic) it coughs, splutters, backfires and then cuts out. So far we have fitted a kenlow fan (the radiator has been re-cored), a new coil and condenser. I can hear the petrol pump so think that is working ok. Someone suggested something electrical, but we've done the coil and condenser and don't know what to try next?
Thank you in advance.
Rod.
The car starts and runs fine then when it gets warm (or we hit traffic) it coughs, splutters, backfires and then cuts out. So far we have fitted a kenlow fan (the radiator has been re-cored), a new coil and condenser. I can hear the petrol pump so think that is working ok. Someone suggested something electrical, but we've done the coil and condenser and don't know what to try next?
Thank you in advance.
Rod.
I've been having the same problem on my XK150, I'm hoping that its the ignition as that is currently being replaced. There was a thread about it here back over Christmas/New Year time.
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
a8hex said:
I've been having the same problem on my XK150, I'm hoping that its the ignition as that is currently being replaced. There was a thread about it here back over Christmas/New Year time.
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Thank you for that I'll have a read up on that.http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Rod.
Fuel vaporisation is possible, but check the rotor arm first as the easiest thing to replace.
Buy a red one from the distributor doctor. (Google it). The plastic is superior. The original Lucas bakerlite used to break down over time allowing the spark to travel down the distributor stem instead of out to the plugs.
Later cheap rotors made in the Far East were even worse, especially when they held the brass part on with a rivet.
Buy a red one from the distributor doctor. (Google it). The plastic is superior. The original Lucas bakerlite used to break down over time allowing the spark to travel down the distributor stem instead of out to the plugs.
Later cheap rotors made in the Far East were even worse, especially when they held the brass part on with a rivet.
Vanin said:
Fuel vaporisation is possible, but check the rotor arm first as the easiest thing to replace.
Buy a red one from the distributor doctor. (Google it). The plastic is superior. The original Lucas bakerlite used to break down over time allowing the spark to travel down the distributor stem instead of out to the plugs.
Later cheap rotors made in the Far East were even worse, especially when they held the brass part on with a rivet.
Thanks for that, have ordered one should be here Wednesday.Buy a red one from the distributor doctor. (Google it). The plastic is superior. The original Lucas bakerlite used to break down over time allowing the spark to travel down the distributor stem instead of out to the plugs.
Later cheap rotors made in the Far East were even worse, especially when they held the brass part on with a rivet.
Rod.
OLDBENZ said:
I had a similar thing with my XK120 OTS. It turned out I was missing the insulator blocks between the carbs and the inlet manifold. Installing these seemed to do the trick.
That would definitely do it. I have a 120 OTS in Dubai, run in 30-40c and dont have fuel vaporisation problems with those blocks in place. My small block Corvette when I had it here, was terribe for fuel vaporisation as there was nothing to stop the heat from the intake manifold seeping into the carb.With mine the ignition was replaced, sadly the people building the replacement forgot to do it in time for the XK club trackday so I got lent a replacement which probably wasn't setup quite right for the engine. This massively improved things. But she still wasn't pulling right above about 4K and at that speed started to sound like she was running on 5 1/2 cylinders. Pulling all the plugs they all seemed to be OK so we reseated everything. I also found that my manual choke had crept back on a bit and pulled the lever back home (I think it needs a return spring). Lastly I removed the socks from the ram pipes. After which she went like a train.
At least she went like a train till I drove home when she started to miss fire all over again.
The next time I took her out she just wouldn't pull about about 3K.
I found that socks had been sucked hard into the ram pipes, so I guess she was being strangled.
I must order a set of new socks. Her proper ignition is waiting for her down at Winspeed too now so hopefully she'll be running right before the next trackday in June. I can't wait.
At least she went like a train till I drove home when she started to miss fire all over again.
The next time I took her out she just wouldn't pull about about 3K.
I found that socks had been sucked hard into the ram pipes, so I guess she was being strangled.
I must order a set of new socks. Her proper ignition is waiting for her down at Winspeed too now so hopefully she'll be running right before the next trackday in June. I can't wait.
Vanin said:
Did it cure the problem or are you cursing me for wasting time and money?
Haha, I would never curse any help I get.Unfortunately the problem is still there although takes longer to happen now?
So to recap we have fitted
New condenser
new coil
new red rotor arm
new spark plugs
also had the feeler gauges out last week.
I'm away this weekend so I'll be checking some wires next week would love to sort this as the weather is so good lately.
Rod.
Just tried to start the XK120 after a month or two of inactivity and it would not start. Electronic ignition was tested and there was a good spark. Fuel pump was ticking, I was a bit like you and a bit bewildered.
Flash of inspiration and took a small hammer and tapped the side of the carb float chamber and sure enough the pump started ticking madly.
Stuck float, maybe worth a try. Sticking float in your case may be wiser to remove float chamber and float and give a thorough clean. Maybe a bit of grunge is causing it to stick occasionally.
In my case it started first time, just go easy with the hammer!
Flash of inspiration and took a small hammer and tapped the side of the carb float chamber and sure enough the pump started ticking madly.
Stuck float, maybe worth a try. Sticking float in your case may be wiser to remove float chamber and float and give a thorough clean. Maybe a bit of grunge is causing it to stick occasionally.
In my case it started first time, just go easy with the hammer!
It sounds more like a fuel problem to me - certainly the symptoms seem like fuel vaporisation. My own XK120 ots is overcooled if anything and being out in NE Scotland it takes ages to warm up, though I must say it is better actually having a thermostat fitted as there wasn't one when I bought the car. The point of this nonsense is that it might also be worth checking the thermostat if overheating is leading to vaporisation as underbonnet temperatures can get high with such a big engine.
Dont dismiss the electric pump just because you can hear it running, my Lotus Elite would run fine cold then die when hot, after replacing a load of ignition bits it took me a while to find it was the fuel pump (as it was a new FACET one), bench tested the pump, it would run fine for ten minutes, splutter then output would stop though the pump still sounded as if it was running fine.
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