So last spring after our 99 XJR arrived in our driveway with a restricted performance message I pulled the tank and replaced the fuel pumps. Undoing the fuel lines was the worst part of the job (if I don't count cutting my forearms to ribbons on the tank opening). They seemed to click in place ok when I was putting things back in place but being that I couldn't see them I never had a comfortable feeling about that part of the job. I've been catching wiffs of gas and have noticed that the big cat seems to crank a little longer when cold so I was thinking I had a leak, even though I couldn't see anything on the driveway, that was bleeding pressure and the extra cranking was my sign that the pump had to repress prior to starting. I gave the car to my neighborhood shop today and asked them to look for a leak. They found none but noted that I had overfilled the tank. I typically run the tank low then fill completely until the pump shuts down (no extra squeezes). The shop said a full tank could lead to my slow start symptoms as well as produce the gas smell. The problem with that explanation (for me anyway) is that the car is not always overfilled but the slow start and the fumes seem to be consistent.
My question is could something in the evap system be plugged or swamped with liquid and causing the slow start? This behavior seems to have changed some time (months at least) since I had the tank out. I never have trouble starting (no need to do anything to the pedal, just hold the key longer) and I don't notice any extra smokiness (my 540i used to look like a mosquito fogger when the crankcase breather diaphragm was torn on a cold, < 20 F, start) and I see no running issues. This doesn't seem to be a temperature (outside the car) dependent problem as we've gone from 20 to 70 (F) at various times (the same day even) over the past month. I'm not sure what components make up the evap system that can be checked but if you have any ideas, toss them out.
Thanks.
Doug

 

You may want to pull out both charcoal canisters and see if you can pour fuel out of them. They may be completely saturated. If they are, you can put compressed air into one of the ports to dry it out, otherwise you will have to get new ones. While you are at it, pull out the canister close valve, which is attached to one of the canisters and check if it is clean and operates by putting 12 volts on it. These items are located adjacent to the rear jacking points under the car. Don't overfill your tank the next time. Please see attached photo and diagram of evaporative system.