strong (eye watering) smell of gasoline when starting out in 1st gear, lasts for about 10-20 seconds then goes away until next start from a stop. no sign of leak on ground while idling. in fact, does not smell while idling at all. only after moving away from a stop. when the hood is opened the smell is very, very strong. happens with 1/2 tank all the way down to 1/8 tank. this was occurring on a very, very hot day after driving for about an hour. it was so hot that the metal shift lever was too hot to touch, and the hood's safety latch would burn an unprotected hand.

started out at 9;00 a.m. this morning. was about 65F. filled tank. traveled at about 55mph for about an hour. no smell and did stop at a few stoplights. the ambient air temps went up to over 100F, was in start and stop traffic for about 20min when i started to notice gas smell in cabin. had to travel about another hour in suburban traffic to get home. temps stayed at 100F+ and at every stoplight and stopsign the cabin would fill with fumes only after starting out from the stop and only for about 10-20 seconds.

i'm starting to think that the acceleration is forcing standing gasoline to rise to higher levels towards the rear of a container that holds gasonline in the engine compartment. i know of three, offhand that do. two floatbowls and a fuel filter. my bet's on the fuel filter. anyone that wishes can offer an opinion, comment, anecdote, criticism, etc. i want this fixed in a hurry so i can drive the car across the country this month.

i'm hard to offend, on a forum anyway , so fire away!

oh...the car's a new-to-me, restored '67 mk2.

 

It could also possibly be the AED.

 

thanks for the interest.. does the AED store gasoline in it, such that an inertial force could make it leak out?.

BTW, i have yet to actually get under the car and have a look-see. it just happened today during the latter part of a 200 mile drive in excessive heat. i'll be doing a bit of physical investigation soon, not just this theoretical stuff i'm doing now. thanks again!

 

When accelerating, the engine tilts a little on its mountings, slightly stressing the fuel lines from the filter to the carburettors. I'd begin by checking the joints on those and the pipes themselves. When everything is right, SU carbs produce less fuel smell than others.

 

thank you very much, i'll start there.

 

There are loads of areas to look at. The S type (I know yours is a Mk2) has a problem with leaking fuel tanks due to there position in the rear wings. The Mk2 tank is in the bottom of the boot but the fittings are similar so I would check first that the tank is dry as you have said it happens when the tank has between 1/2 and an 1/8. Normally if it was a hole in the tank it would happen when the tank is full and go away when the tank only had an 1/8th but worth looking. Check the fuel lines and joints around the fuel pump. Just because you think the leak is in the engine compartment it might not be. As the car moves the air flow over and under the car can cause fuel vapor from the back of the car to enter the passenger compartment.
Check the fuel line from the back of the car to the front. It is a copper pipe that runs along the inside of the right chassis rail and can be hit by a stone causing a leak. Check all the joints at either end the copper pipe should be one piece right up to near the glass bowl where there is a soft pipe leading to the bowl. Check all the soft fuel lines, if you are using E10 fuel you might have a soft fuel line that has been compromised and is weeping. The Ethanol in E10 will rot any fuel line that is not E10 compatible.
The glass bowl should not give a problem unless the seal is not sat correctly or it is not screwed up tight, having said that check there are no cracks in the glass. All the banjo bolts should have two fibre washers one either side. These can be damaged or need to be cinched up tight.
A typical fault which would cause the smell of fuel in the engine compartment is a stuck float valve allowing more fuel into the float chamber than is required. The level of the fuel in the float chamber should be set at a level which is the same as the needle valve in the mouth of the carb. If the level is too high then you will get excess fuel sitting in the carb mouth which can run down into the air funnel and down the nylon pipes to the ground. The front float also controls the height of the fuel in the AED which is open to the engine bay.
Lastly check that the banjo bolts on the bottom of the front carb are tight. There is a bridge piece that connects the front carb to the AED. It is very difficult to get to and has two different odd sized Whitworth bolt heads so use a small adjustable spanner to cinch them tight.
Fuel leaks can be hard to find as fuel can just evaporate away leaving the smell but no visible signs of a leak. I use blue paper hand towel which you can buy on on a roll. If you dab this along the fuel lines and bottom of the carbs checking the colour after every dab it will turn dark blue when you come across an area where the leak is. You can then clean the area and try again honing in on the culprit leak.
Good luck finding the leak it is not at hard as finding an intermittent electrical fault.

 

Yes the AED has fuel in it at all times.

 

Cass made a good point about E10 fuel. Our cars shouldn't have great problems with it so long as incorrect materials have not been used as replacement parts. The line from the filter to the engine has a nylon section, which is fine and will withstand any fuel blend even if it looks old and dirty. However, it's all too possible that someone has replaced it with a nice new piece of PVC tube, which is close to useless.

The Mk2 fuel tank usually corrodes first at horizontal flange where the top and bottom halves are welded together. However, you don't usually smell leaks from there when the car is moving - or at least I haven't. I'd definitely start at the two banjos on the filter, the lines from there to the float chambers of the carbs. They're easy to reach and likely candidates.

 

Just a wild guesstimate about the AED
Is it possible that the spring in the AED has failed?
Vacuum holding the valve closed at idle.
reduced vacuum allowing the valve to partially open under acceleration?
fuel the backflowing through the AED air intake?
As i said just guessing

 

Excellent write up by Rob/Cass.

When opening the bonnet/hood of a non running Jag with Thermo SU's. The biggest stink of gas/petrol comes from the AED.

 

took car to a jag service center in the east bay that is reputed to be the best in the area. he tightened some loose fittings in the area in and around the AED and suggested i take if for a spin. the car had not been running for two hours. IOW, it was cold. the ambient air temp was 100F. i took it for a 15 minute drive and there was no evidence of a gasoline leak or smell. i paid him and proceeded to drive the car home. it was a 40 mile drive in 108F temps and in afternoon traffic. speeds were 10-12 mph in stop and go traffic for miles. i saw no less than three cars sitting on the side of the highway from engine trouble. during that drive the car suffered massive raw gasoline odor, decreased power, and for the last five miles i began to detect the ominous smell of overheated wiring. the brake handle was too hot to touch with the bare hand as was the shift lever and knob. i pulled off at the next exit even though on two miles from home and let the car sit for 45 minutes. i eventually made it home.

i am considering the entire two day fiasco to the outrageous heat we are now experiencing out here in california. surprisingly, my 2001 dodge ram 1400 with a five-speed manual works perfectly well in this weather. after all, there ARE limitations WRT ambient heat temps in powertrain design.

 

Ouch ~ suggest you be careful until this matter is properly diagnosed. The last thing you want is a car fire. Burnt wiring & gasoline do not good friends make.

 

I think it's the AED + the hot weather.
The car is idling at the stop sign, and you take off and the float needle valve opens further and floods the AED (the gas smell).
This goes away when you get moving.

You should be able to create the situation by getting it up to temp and do the same thing in your drive way.
Let it get hotter then normal, but be carful, be sure to have a big fire extinguisher with it reach.
Don't use your hand to open the butterfly valves, have someone in the car hit the accelerator while you watch.

I created a bigger vent line on the tank and lowered the float level using 1/2 stock, you could probably even go bigger with the stock.
Using some carb isolators may help too, that may have been mentioned earlier.
The float level directly affects the level at the AED, at 7/16 it's almost at the edge of spilling over.

 

I agree with Jeff. Drop the float level to 1/2 rather than 7/16. It will not effect the running of the engine as I doubt you will every be racing your engine to a point where you need every fluid ounce of fuel from the float into the carbs. I had a similar problem but only with the front float chamber. Smell of fuel in the car. Dropped the float level and it has gone and it cured my running on problem.
Better to be safe than fast.

 

I agree wholeheartedly with Jeff, Rob & anybody that will listen. As I said above I would be suspicious of the AED. Dropping float levels can do no harm & is sensible.

Please, please, please have adequate fire extinguishers close at hand.

 

Is a garden hose any good in a gas/engine fire Glyn ?

Huey, through all of this, what did the temp gauge say when it was very hot, I don't think it was mentioned anywhere ?

Ignition timing could be too far retarded and/or too lean.

I would like to see one of your plugs the next morning after a HOT run.

 

Not really Jeff. I could show you some awful films of petroleum fires. A garden hose can do no harm with a nozzle that casts a mist spray over everything but it can't do what a fire extinguisher can. Carbon dioxide extinguishers (CO2) are the best as they starve the fire of oxygen. 2nd best are powder extinguishers. They just make one hell of a mess to clean up afterwards. Why the racing fraternity hate Marshals using them. I carry a CO2 extinguisher in my Jag even though every harness is new. My insurance depends on one doing that.

 

temp gauge is in celcius and it read between 100-110C when driven for 45 minutes on the freeway while creeping along in evening commute traffic at 10-12 mph. engine was about to stall and would only reach 45mph with pedal to the metal. had to pull off and let it cool off for an hour before i could make it home. ....let it sit for about 10 hours and at 4:00 a.m. this morning the engine was still warm, but started and ran as it should. i don't think i've permanently damaged anything, but i've decided that like a few of my other british vehicles i've owned over the years (a '68 BSA motorcycle, a '61 mga, a '53 mg td, and now this new-to-me '67 mark 2) they all have overheating problems, that manifest themselves in various and sundry ways. this car is no different. i'm not including my 2007 aston vantage, but then again i don't think i've driven it in 100F+ temps either. i do know that the AC in it is not adequate for temps approaching the 100F's though.

so that's what i'm chalking this up to be....just another pre-70's british engine compartment that will overheat more readily than any other vehicles i've owned. so be it.

and, BTW, i thank all the contributors, i've taken all the comments seriously, and i can assure you that they are all very much appreciated.

 

I'm delighted to hear that. A friend restored a Mk2 and went the cheap route of not replacing the wiring harnesses which he knew to be in a bad way. The fabric insulated wiring was still fine but the early plastic insulated wiring had deteriorated badly to the degree that some of it was cracking & falling off. Result was a totally burnt out restored Mk2. and it was a lovely car. It's not difficult to check harness insulation. In a car that has lived in a cold climate it will almost last forever whereas in hot Africa I replaced every harness in my car during restoration.

 

It's overheating and causing the AED to dribble fuel.

100 F is around 37 Celsius _ hot, but not like 40 to 42 Celsius, it shouldn't be over-heating at 37, mine will hover around 90 when really hot outside, and normally will run at 70, which is a bit cool.
Maybe the air-conditioning pushes it over the edge.
I would start looking into the cooling system and the ignition as mentioned.