i've been thumbing thru the forum here and feel practically blessed for having found this site. i own an 87 XJS 4.2L which recently developed what appears (at least on the surface)to be a fuel delivery problem. the car is hard starting, more so hot than cold, but in any event doesn't want to stay "lite" if i remove my foot from the accelerator pedal, there is also a low rpm miss that is noticable.

although i had replaced the fuel pump and fuel filter within the last 6 months my first thought was that the likely culprit was another clogged fuel filter, so i replaced it but the problem remained. my next bright idea was that the potential offender was some kind of vaccum leak, so i got out the old squirt bottle filled with a ton of soap and sprayed every hose i saw...the benefit here were clean hoses, but no indication of a leak and the car ran the same.

other recent replacements have been the coil, and a minor tune-up (spark plugs - wires, etc) which also occured about 6 months ago.

as an aside i have to say the the car is one of the most stunning vehicles on the planet, past or present....it gets looks and comments where ever it goes. now if i can just figure out the problem i can get back on the road and gather more ego building stares :)

thanks for any help you might be able to offer!

Submitted by gaelicism_1@ya… on Mon, 12/19/2005 - 16:09

one of the most perplexing things about this particular problem was that although there was a significant miss, and the car wouldn't idle, it ran relatively well in forward. such was not the case in reverse, all problems increased in serverity 10 fold. after reading your post Doug I went and checked the bellows, and sure enough it had disconnected itself from air flow meter allowing air to seep in. when the car ran forward it produced a semi seal allowing the car to run, in reverse the bellows would pull away completely causing the car to become inoperable!

happy holidays & thanks for your help :)

Submitted by dougdwyer@adel… on Thu, 12/15/2005 - 22:01

Well, we're already here....maybe the whole thread can be moved at some point.

I would first check the bellows/trunking from the air flow meter to the throttle body. A split or poor seal here will give the condition you are describing.

Also check that the throttle blade is set to the proper .002" clearance and the throttle body itself is not clogged with oil-carbon deposits.

Post back !

Cheers

Doug Dwyer
Longview Washington USA
1987 XJ6 Ser III
1988 XJS V12 Coupe

Submitted by gaelicism_1@ya… on Thu, 12/15/2005 - 15:58

my most sincere apology, not only did i get the model wrong, it's obviously an xj6, but i posted in the wrong forum :(

if the forum has a moderator maybe he/she might be so kind as to move my post, thanks.

skol

Submitted by dougdwyer@adel… on Wed, 12/14/2005 - 21:14

Let's clarify what car you have :-)

An '87 XJS would have a 5.3 litre V12 or a 3.6 liter inline six.

A 4.2 litre is an inline six used in many Jags but, in the vintage we are talking about, would have been used in an XJ6 sedan

Cheers

Doug Dwyer
Longview Washington USA
1987 XJ6 Ser III
1988 XJS V12 Coupe