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Jag barely runs in cold weather

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sarge2d

Freshman Member
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In prep for the approaching clod weather, I have a problem I hope someone can help me with. My 89 XJ6 will not run above an idle in extreme cold weather. 32F/0C. When you attempt to give it throttle, it will bog down and barley run. The rest of the time, it runs fine. It used to have a vapor lock issue, but I have corrected that. Any ideas?

Thanks
 
I would guess, based upon the information given, that you have water in the fuel system somewhere, or a pump that is on it's way out and doesn't like the cold.

A fuel flow test (fuel line run over wing to a bucket/can on the ground) and crank it whilst cold.

Can outside is important unless you know what you're doing and are absolutely certain there are no loose sparks flying around.

FIRST thing I would do was a flow test.
Second would be pressure.

Once you eliminate fuel issues, we move on.

I add dry-gas, Heet, or some other gas-line water absorbent/antifreeze every couple of tanks in winter, just for that purpose.

If the water has settled in the filter, when it freezes, it acts like a plugged filter, and won't run over idle.
 
Also read the thread below on the XJS with running problems. The commentary on the Throttle Position Sensor, and Coolant Temp Sensor apply to your car also. You could also have a Crank Position Sensor that is just starting to fail. They are notorious for failing in the cold. Usually the car will not run at all, but a partial failure is possible.
 
If the sensors are known for that in cold weather, okay.
Sure sounds like frozen fuel to me, especially when it only happens when he hits 32F or 0C.
 
Thank you so much for your input. I will look into that and let you know. May be a while on the return. Thanks again.
 
I appreciate your thoughts. May take a bit as these issues sound somewhat involved, but will post back if I discover the issue. Thanks for your time.
 
I'm not sure my response sent. Thanks for your time in responding to my post. It may take a while to determine as this sounds somewhat involved, but will let you know if I figure it out.

I'm not sure of the thread you referred to. I couldn't see it.

Thanks
 
When I was working in the Jag shop we had several of those with contaminated fuel and it required removal and flush of the tank and a pump replacement.
 
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