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Got a Jaguar XJ6 here with an intermittent sticking needle problem. Anyone know how these needles go in and out? Tried to remove the first one based off a similar YouTube video and I appear to have pulled the shaft out as well as the needle and now can’t realign it, don’t want to do the same to the rest. Hoping someone has some tips, TIA

In the workshop we have 3 different manufacturer vehicles with a diesel fuel problem. Two have been fuelled with Petrol. I am trying to find out information, however I having difficulty finding the answer. On the high pressure fuel pump at the engine, remove the tank return pipe and insert a pipe to a collection container. Turn on the ignition, the tank pump primes and stops when the pressure reaches about 4-5bar at the fuel supply port of the high pressure pump. Am I right in saying there should be no diesel going back to the tank from the high pressure pump until the engine is cranked? What is the expected resistance of the return valve solenoid / pressure regulator in the high pressure pump? Using Alldata and it is not mentioned on the 3 vehicles.

Mercedes B180 2016, Diesel, Renault engine. Back story, Customer put petrol in!!!!!. Drove car, then engine stopped. Called Fuel Dr, they cleaned lines and tank. Engine ran for a couple of weeks then Engine stopped again. Called Fuel Dr again, told all is good however customer told them to do it again. Car never ran. Came to the garage. 1/4 tank of diesel in the tank. Only fault codes were low fuel pressure related. Has a long cranking time, varies from 2-10sec. Did a Picoscope capture on fuel tank, 3 phase motor and all good. Did Picosope on injector using Amp clamp and all injectors are good. Did an injector leak off test. small amount of diesel going to the vials. Removed fuel intake line to fuel filter, primed tank pump to remove excess fuel. Changed fuel filter put 6ltrs of diesel in tank and primed the pump and filter. All good. Pressure at high pressure fuel pump on start is approx 500bar then goes to 250-300bar. Then engine stops. Pressure at high pressure fuel pump drops to 0bar in approx 1 min. Checked fuel at injectors and there is fuel and pressure. Changed high pressure fuel pump and timing belt (was due a change). Told ECU new high pressure fuel pump. Reset adaptive values. Still the same, starts and runs for 2 sec then stops with various cranking times Difference after new high pressure fuel pump and timing belt is there are no fault code present, alternator appears not to be giving out a charge. Sounds and feels like the engine is being told to stop after it start. Q. Could alternator no lin signal cause that? Other ideas beside new injectors? Going to do a injector amp and voltage check tomorrow.