Hello friends, I wonder if I am on the right track? My 84 series 3 4.2 has a strong smell of fuel in the car, along with a loss of mpg. It is down by about 5 mpg. I am sure it is running rich and I am thinking maybe the cold start injector may be jammed and spraying fuel into the manifold even though the engine is hot. I havent yet started to read voltages but I think it may be wise to ask the members of this great forum if they have experience of this problem. Any thoughts will be welcome. Regards, Danny.

 

Here are some conversation starters on rich mixture/over-fueling.....



XJ6 Series - EFI Rich Mixture


The cold start injector being stuck open is a possibility. Remove (and plug off) the supply hose and see if anything changes. An electrical malfunction of the cold start system is less likely, though, due to its design.


Cheers
DD

 

Thanks Doug, you always very quick to offer your advice! It is much appreciated. regards, Danny.

 

Is the mpg figure from the trip computer or from fuel guage and odo? If it is using heaps of fuel and smelling inside of fuel, It could be doing what mine did. My fuel pump started leaking very badly when it was running, dripping fuel out from under the spare tyre well. I lost a lot of fuel, and it was very smelly inside. Just one of the many things to look at (and easy to check too)
If the mpg figure is from the trip computer, then it probably won't be the pump.
Good Luck

 

Many thanks Richard, my mpg loss was reported by the computer. I did look for leaks in the boot and the pump and hoses all check out ok. Kind regards from the other side of the planet!
Danny.

 

Check the pump like Richard said.
A series 3 is an old car now, be sure to check all the fuel lines (hoses) for cracks, I think a STRONG smell of fuel wont be down to a faulty injector.
If you're not sure about them, replace them.
Pinch 'm, if they show any cracks, get rid.
And be sure you get the right ones, no run of the mill rubber, but propper fuel and pressure resistant ones.

 

Thanks Haddock, good thinking. The exhaust does have a rich smell though.
Kind regards, Danny.

 

Any old straight six (I love'm)should have that, they're not ment to be lean.
Those were the days!


Theoldgit.

 

Start with the basics, check all fuel lines have not perished, each injector has a rubber fuel line, these get rock hard and brittle, even the O-rings on the injectors can leak.


Old age can also lead to the tanks rusting out, and without a pre filter to the fuel pump can destroy the pump quickly, but also eventually gum up the injectors possibly causing one or more to stay open or give inconsistent results.


Overhauling the fuel system is always a good idea to do anyway if you are unsure of the age of it all, I always do that to a newly purchased old car for peace of mind for future motoring and to eliminate any possibilities like stuck injectors.


There is also a lot of other variables, and the link that has been given is a great starting point

 

Many thanks Stoney,
I have found the link that Doug sent very informative. As my mpg loss is very minor, approx 5mpg, I suspect that rich running and not fuel loss is the reason. I have inspected all the rubber lines and they appear sound and no signs of cracking. I did remove the coolant temp sensor and tested it on the kitchen stove with a thermometer and resistance meter. It checked out perfectly. I next want to eliminate from suspicion the cold start injector. Doug said it may be sticking. He also said I might try removing the fuel line to it and blocking it off. I am now looking for a suitable plug. I think it may be 3/8"?
I cannot find a fuel leak and the smell of petrol is not too strong. I did notice yesterday when I was revving the engine there was some black smoke from the exhaust which may well mean a rich mixture. The spark plugs are a nice brown on the electrode but do have a black sooty look on the inside.
I will report back once I have blocked off the cold start injector. Thanks once again to all members who have helped me. Regards, Danny.

 

5/16"....same as the 6 regular injectors



Cheers
DD

 

Thank you Doug.
Kind regards, Danny.

 

no need to "block" the CSI, just disconnect the plug from it.

as to the fuel smell inside the cabin, there are two "fuel vapor tanks", one on each "C" pillar, to the left and right of the rear seat, rearwards of the rear doors. you can access them somewhat by removing the "C" pillar trim, the trim just pulls off with spring brackets. there are rubber hoses connected to each of the vapor tanks, checking them will reveal if they are connected or loose or cracked. NOTE: I do not know if this system is the same in UK cars).

the second possible cause of a fuel smell inside the cabin are deteriorated vent flaps in the panel behind the rear seat Back, and in the rear cowl tray.

checking the flaps behind the rear seat is easy, just remove the upholstered panel in the trunk, the panel where all the electronics are located behind it, and you will see the vent flaps hanging. The factory glued a piece of headliner material to a thin metal flap. if this fabric has separated from the metal flap, the flap will not seal the interior and you will hear a tingling metallic noise everytime the flap moves and contacts the metal.

the flaps behind the rear cowl are another story, there are 4 of them rivetted to the black tray under the cowl. Those are the first to loose the fabric. You will need to remove the tray, disconnect all the hoses, etc., and carefully pull the tray once all the nuts are removed because the tray is glued with a gooey silicone adhesive.

 

Unplugging the CSI eliminates the possibility of an electrical malfunction.....but leaves wide open the possibility that it is dripping gasoline. Blocking it off confirms it was the problem....or eliminates the CSI system entirely.

No reason a person couldn't unplug it first and then block it off, of course, but the way the circuit is designed the possibility of an electrical fault is a bit unlikely

Cheers
DD

 

Worth fixing, but you'd still have to trace and repair the actual *source* of a fuel odor!


Cheers
DD

 

Thank you Doug & Jose for your further ideas. I have now removed the fuel supply to the csi and fitted a 5/16" plug. next step is to take the old girl out for a 20mile trip and see what the computer says the mpg is. I have had this car since 1986 and always had a return of at least 20mpg, up to 26 on a long run. Lately, I have been getting 16 maximum so something has gone wrong. I hope it is the injector, an easy fix. Jose,the possibility of the loose flaps in the cabin is of interest, I will certainly look at them soon. I seem to remember always having a slight smell of fuel in the boot,(trunk) but never took any notice. Perhaps my flaps are now allowing the odour to the cabin. Watch this space for updates! Kindest regards to you both, Danny.

 

you welcome Danny;

if you have had the gasoline smell for a while, there must be a leak somewhere.

check the fuel filter and fuel pump hose connections with engine running, you might detect a drop of gasoline slowly spurting out. (spare tire compartment). Remember that fuel droplets dry almost instanty, so you need to catch it when it is happening.

 

Here's a trick I learned from a fellow Jag -lover....

Wrap all fuel hose/pipe connections in colored tissue paper. The *slightest* oozing of gasoline will stain the paper....thus telling you which connections are to blame.

A small amount of raw fuel can make a huge odor.

Cheers
DD

 

That sounds a great method Doug, well worth a try. Jose, also a great thought as the pressure is going to be up with the demand for fuel to a running engine. Thanks again guys. Regards, Danny.

 

Jose, your suggestion of running the engine and inspecting the hoses and connections in the spare tyre bay has paid dividends! I managed to see a tiny droplet of fuel leak from the pump outlet! After de-pressurising the system, I removed the hose, cut off 1/2" and refitted it. Whilst I was at it, I checked the rest of the hose clamps and found a few were not really tight. I suppose after 31years, the rubber has compressed somewhat. I am delighted to say that there is now no sign of leakage in the boot. It will take some time I imagine for the smell to disappear but hopefully, all I have to worry about now is the rich running! I am hoping that will show positive signs with the CSI temporarily disabled. I am most grateful to you and the other kind members including Doug who have taken time to assist me. Kindest regards, Danny.