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View Full Version : JAG XJ6 FUEL PROBLEM



Steve
07-09-2002, 04:57 PM
Gary, hello and welcome! I'm going to just brainstorm here, and maybe we can come up with a solution.

This sounds as if the problem is the carburetors dumping way too much gas into the inlet manifold. I have not heard of this happening before, but it is almost as if the fuel delivery system went haywire. If the fuel pump went ballistic and started over-pressurising the system, would the carbs flood? And if the float in one of the carburettors was faulty, that might well provide an over-supply of gas. Another consideration is if the choke is stuck on, providing an over-rich mixture.

I would doubt that the fuel pump is hyperactive, so I would look at one or both of the carburettors and the choke mechanism. You should have twin Zenith CD 175s (I believe). I hope that a few others might chime in with some ideas here, but I think I may be close to what the problem is.

Good luck, let us know what you find.

coldplugs
07-09-2002, 05:09 PM
This seems like a lot of gas to get dumped in through the cylinders via the carbs. I'm not that familar with modern Jags but can't help wondering if the crankcase ventilation system might be at fault. If there's a vacuum hose to the intake manifold or carbs, that might provide a path to the crankcase.

The recent fillup might be a red herring or might be a clue. I found the following on the autotruck.net web site:

"The XJ6 sedans, with their dual fuel tanks, had a failing which we continue to see to this day. The solenoids that direct the flow of return fuel back to the tank the fuel is drawn from often fail. In default, the fuel is returned to the right hand fuel tank. Once it has filled the tank to capacity, it overflows through the canister purge line into the charcoal canister, which is hidden under the right front fender. This results in a stream of gas pouring onto the ground from just behind the right headlight and/or fuel going right on into the motor through the purge line, effectively flooding out the engine"


John C

[ 07-09-2002: Message edited by: coldplugs ]</p>

Steve
07-09-2002, 07:52 PM
John, you are good! That sounds better than my idea, but I wasn't as familiar with the workings of the system as you. I had an inkling at the back of my mind that the "return" system might not be right, but then discounted it. I think you hit the nail on the head!

J. Christian
07-09-2002, 10:27 PM
In my 79 xj6, when the airflow meter went bad, the engine was running way too rich, and I was getting a lot of fuel in the oil leaking past the rings. A new airflow meter solved the problem. I know your car is carburetted, but it might be worth looking into. On the other hand, with that much fuel, I'd tend to agree with John.

garyd
07-10-2002, 03:13 AM
Greetings. My wife and I enjoy being second owner of 1973 XJ6 for past 4 years. Daily driver and do most of own work. North central NJ.
Recently filled the tank drove 10 miles and had to be towed home due to smoke from tailpipes, and smoke around exhaust header. Cooled it down and discovered an extra half inch of gasoline in the oil pan.
Anyone heard of this sort of failure, and what events could make it happen?
Thanks, Gary Davis graemlins/cheers.gif images/icons/confused.gif

Claymore
07-10-2002, 04:05 AM
Given that it's a Series 2, I would go for carb problems. Quite possible, one carb has a problem, and the other was enough to keep the car going while the other flooded.