Jaguar Repair: 1985 Jaguar xj6 backfire air flow meter and Throttle switch, air flow meter, 1985 jaguar xj6

Question
My boyfriend just acquired a 1985 Jaguar xj6, which has a few problems.  He is having 2 problems, one of the fuel tanks switches on the dash will not stay depressed, but it still starts.  The second problem is a major problem.  While the car was running, it backfired through the large crinkled hose between theAir flow meter and the throttle switch.  What do you suggest should be replaced?

Answer
Hi Colleen,
If the dash switch will not click into place he needs to replace that switch as there is no adjustment to the switch.

As for a back fire into the intake, that can be caused by many things. The first test is to run a compression test. That will establish weather the combustion chamber is OK. Each cylinder should be from 135 to 160 PSI with little difference between cylinders.

Timing should be checked and under what circumstance did it back fire? If it happened when the engine was cold and a quick throttle was applied he needs to check fuel mixture (CO) when the engine is cold. (the injection temp sensor has much influence in that condition plus the fuel pressure (32 PSI with manifold vacuum and 42 without manifold vacuum)

I am sorry that there is no simple item that anyone can tell you to go purchase to solve his problem because the engine and injection system is too complex and requires tests to determine what is wrong.

You need to locate a Jaguar specialist in your area to run the tests.
Howard