TR6 Pi Strong Smell of Fuel in Cabin

[Trever the rever]

I appreciate this is an often discussed topic. I was so pleased recently when I discovered a small fuel leak from the joint between the metering unit and the distributor pedestal. After a chat with Malcolm of Prestige Injection the end result being I replaced the O ring seal and long story short - all well in the engine bay. However after filling up with fuel (97/98 Octane always used) and motoring on 'Drive It Day' the fuel smell was as strong as ever and that was with hood down. By the end of the day and the return leg home, I was just fed up with it. To be honest I've had a smell of fuel for many years now, and have lived with it, initially blaming the twin sports exhaust. I even had the outlets modified to a horizontal alignment to reduce efflux in the air stream.

 

The tank is presently just over half full. I've checked for leaks from the engine to the tank. the pump, filter and all unions look good with no evidence of fuel. However, there was evidence of a long thin stain (albeit now dry, but I would say recent) under the fuel tank, definitely away from the pump and fittings but in line with bottom of the tank. There was no wetness around the tank at any point.

 

I have one theory, the two parallel strips look aged and crusty, I wonder if there is a leak in the tank under these (maybe the upper one) and the fuel particularly when full leaks out and gravitates from there?

 

Has anyone had experience with corrosion under these strips? I could remove them given their condition and this would allow an inspection. Has anyone used a strong light above the fuel cap shining into the tank in darkness to reveal holes. (Safety first considered of course).

 

I'm prepared to change the tank, but it would be good to have the evidence to justify it.

 

Welcome your thoughts. Trevor Hughes 1972 TR6 owned since 1995.

[scousegit]

If you can, empty the tank and remove it from the car. Once you have vented the tank and made sure that it is fume free block all the inlets and outlets securely bar one, and then fill with compressed air then place in a water tank, you will soon find out if you have an extra hole!

 

The same thing happened to the "Wheeler Dealers" TR. They sent to a guy who did this and then sorted the problem a patch and solder. Though it might just be easier to go and buy a new tank as I will have to do on my '72 6.

 

Jon.

[RogerH]

Hi Trevor,

I don't have a TR6 but having read many smelly threads the rubber pipes often have the finger pointed at them.

Many are porous and the petrol smell so powerful you do not need much to create a significant smell.

 

Also the big hose that joins the filler cap with the tank. The rubber can be porous or the jubilee clips not doing their job.

 

If you look inside the tank (be careful) and see rust - usually on the bottom seam - then consider removing it with DeOxC and then use something like 'Slosh' to seal the inside. This will save on a new tank.

 

Roger

[Trever the rever]

Thanks Jon, I guess I'll have to bite the bullet and take the tank out. Shame I've so much fuel in there. Yes I recall the Wheeler Dealer programme. I'm off to the Classic Le Mans in July so there's my deadline! If there's anyone with the suspect corrosion under the strips I'd be interested to know.

[Waldi]

Worth checking the fuel tank, mine had pitting corrosion on outside, but did not leak.

The hoses are another suspect, as Roger indicates.

some hoses, although marked wirh suitable for unleaded petrol can permeate 40 times more fuel than the proper ones. Google SAE J30 on this forum.

Waldi

Edited April 27, 2018 by Waldi

[Trever the rever]

Roger, yes interesting comment about the filler cap hose. I did buy a replacement many years ago, however the chap who put my car back together pre 1995 installed it and tightened the jubilee clips from the cars interior!! hence I cant access in the normal way! As said tank needs to come out for thorough inspection.

[Steves_TR6]

I would suspect the hoses

 

I replaced all the hoses on my 6 and it made a big difference to the smell, most notably in the boot

 

A longer exhaust also reduced dramatically the fumes entering the cabin, but these are exhaust not petrol flavoured.

 

For the modest cost i would replace all the rubber hoses first.

 

Steve

[barkerwilliams]

Trever,

 

You will almost never see a fuel leak it evaporates too quickly. Simplest way is to dust with talcum powder and look for traces in the dust after a few hours.

 

Does the smell get worse with the engine running (fuel pressurised) or is it as bad after being stood for a few hours? If when running then if you park the car on a day without wind and turn the ignition on (disconnect coil) to have the pump running and leave for 10 minutes you should be able to determine if the smell is boot or engine compartment related.

 

I changed my rubber hoses then removed my twin exhausts and my petrol smell went, others have mentioned a badly sealed, or rotting filler tube.

 

Is your pump in the boot or the more recent under floor installation?

 

Alan

[Rem18]

I agree with Trevor.

If you dont want to do a new tank you can buy a slosh that works quite well.-

Truth is there are so many things to nail.

After you fix all the fuel you will still stink after a long hard run...

My dad has a 6 he bought new and many are the memories as a child of the pump noise and car smell and that was from new.....

[TRTerry]

I have had numerous sources of petrol smell over my many years of TR6 ownership. 1. Fractured fixing lugs on an aluminium tank ( twice!). 2. Slightly loose petrol sender gasket. 3. Ill fitting filler pipe leaking just a wisp of fuel, only when brimmed. Found all of these using the talcum powder trick.

[rcreweread]

Trevor/Terry

 

Have sent you both PMs ( Personal Messages) yesterday and I can see that they haven't yet been read.

 

Just in case you are not familiar with the process, if you go to the very top right hand corner of this page, you will see an icon of an envelope - this is your message box.

 

If it has a red tag by it, it means you have a new unread message. Just click on the envelope icon to open it up and see the messages. This where you can also send your own messages to forumites which aren't part of the public forum.

 

There is a method whereby you can set things up so you get an email to tell you that you have a new message, but I don't know how you set that up! Hopefully someone else will and advise.

 

Cheers

Rich

[Peter Cobbold]

Check the curved fuel pipe over the drive shaft. I've had one pinhole and the 100psi spray was smelly ( but not on motorway, at slow speed) Peter

[Paul J]

I had a similar problem on my 4A, new tank did not fix, eventually found it was the filler hose of inferior quality, porous and emitting the fumes into my boot space, no fumes inside the car as I had fitted a firewall that seals the boot space off quite effectively.

 

Well worth trying the cheaper options first, wish I had.

 

Paul

[tr6tuga]

Had the same issue with moist felt, the result...see attach photos

[tr6tuga]

Sorry !

[Mike C]

My cockpit fumes were so strong that I had to change clothes and shower after a long run. For years I accepted it as normal.

 

Fitting new hoses, getting the MU corrected for an over rich curve and fitting a firewall like Paul virtually eliminated the problem. The firewall was mainly fitted to keep petrol out of the cockpit in case my aluminium tank splits in a n accident.

 

In a previous life, I used to specify that industrial petrol tanks be tested to AS 1692, as detailed here :

 

https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0ahUKEwiq7fuGgN7aAhUHULwKHa50BlYQFghDMAI&url=https%3A%2F%2Fwww.scribd.com%2Fdoc%2F120574130%2FAs-1692-Tanks-for-Flammable-Combustible-Liquids&usg=AOvVaw0M0KnWlUMybno_PRzDPAMW

 

If were not installed in a car, car , the Tr6 tank would be a Cat 3 , 150mm hydrostatic test head. To undertake this test I'd probably replace the filler cap connection with a 300mm or so section of rubber pipe. I wouldn't try the pneumatic test - it's too dangerous with the internal condition of the tank unknown.

[Trever the rever]

Thanks guys for this vast amount of information. Im going to have a closer look this week. I like the firewall idea as an improvement project. What do people use here?

 

Ill order new rubber hoses anyway, I already have the filler cap one. New joints and strips too in readiness.

 

A closer look at pipework under the car is a must, although I had the full length of pipe replaced front to back not long after I bought the car in 1995. I recall seeing a leak under the car after standing. Manvers Triumph did that for me. Ill check anyway.

 

I still think Ill end up with a tank removal, hence Im borrowing a 25 litre jerry can from my old work!

 

Thanks again Trevor

[Trever the rever]

Just seen the moist felt photo, thats a hole? Trevor

[stuart]

Thanks guys for this vast amount of information. Im going to have a closer look this week. I like the firewall idea as an improvement project. What do people use here?

 

Ill order new rubber hoses anyway, I already have the filler cap one. New joints and strips too in readiness.

 

A closer look at pipework under the car is a must, although I had the full length of pipe replaced front to back not long after I bought the car in 1995. I recall seeing a leak under the car after standing. Manvers Triumph did that for me. Ill check anyway.

 

I still think Ill end up with a tank removal, hence Im borrowing a 25 litre jerry can from my old work!

 

Thanks again Trevor

18SWG Aluminium is material of choice for a firewall and seal all round.

Stuart.

[Trever the rever]

Today I've made some progress. I have removed the tank after siphoning off around 25 litres of fuel. A 20 litre jerry can borrowed from my former place of work (an oil refinery, now a fuel terminal!!) was perfect for the job. The defects I found were:

 

1) a poorly fitted and poor condition connection hose from the filler cap to the tank.

2) A very poor filler cap seal which the cap protrudes through. I have spares of these ready to refit.

3) A very poor condition length of rubber hose connecting the metering unit return line to the tank.

4) I could see no obvious pitting on the tank ribs, however there was heavy paint breakdown around the sender unit joint and from there in a downwards direction. See attached photo.

5) Rremoving the tank from the car and with just residual fuel in the tank. On inverting the tank to decant the remainder, it was plain to see fuel escaping freely from around sender unit joint.

6) This I believe responsible for the paint breakdown and the poor condition of felt strips.

7) In summary potential vapour loss from three areas on top of the tank, and with a tank full situation, liquid loss to the front of the tank too.

 

Prior to removal, I ran the pump circulating on the battery with the coil disconnected for 15 minutes. No leaks anywhere were observed. Fuel was clearly returning to the tank as design.

 

I am going to rub down the front side of the tank, the rear is near perfect, and exhibits a Stanpart sticker suggesting the tank was replaced in the pre '95 rebuild. If I do not see any evidence of a leak, I'll paint up and replace the tank in the car and try it out. I have bought new joints, rubber hoses as need be. I'm in two minds whether to fill with water to double check, now I've removed the tank its not a too bigger job to repeat the exercise.

 

Ah yes the fire wall is under review too. We've a fine specialist metal supplier nearby in Southend on Sea.

 

Welcome your thoughts once more, you've all been very helpful, and given me the confidence to get this far.

 

Trevor Hughes

[Waldi]

You can do a pressure test with air, with a very low pressure and soapy water, this will give a better indication than filling with water.

 

Safety:

Be carefull with overpressuring, 0.05 to 0,1 bar is enough.

Use a clear hose and the waterlevel as measurement of pressure, the gauges on air compressors are not accurate enough.

Only add small amounts of air to the tank, do not leave the feed open.

If you do not feel comfortable doing this, then DONT.

Regards,

Waldi

[Mike C]

Pneumatic testing is dangerous due to the fair amount of energy stored in the air.

 

If I were air testing I'd run a clear hose from a tank nozzle to an area where I could set it up as a water manometer and overpressure relief vent ( sometimes called a "lute").

 

I'd then gently pressurize the tank until 120mm (maximum) of water showed on the manometer.

[Waldi]

Thanks Mike,

That is what I tried to say.

Pressure (leak-) testing with air is common, but only for low pressures with the right precautions.

Regards,

Waldi

[Trever the rever]

Well, I've had an interesting time with my fuel tank, job completed now all within a few days of raising the topic on this forum. I removed the tank after siphoning out the fuel. I upturned the tank to remove the residual fuel assuming it would come out of the filler tube. It didn't, most decided to flow from the sender unit joint! This was the prime shocker, however as you'll see in the photos, there were four offending items.

 

The sender unit joint

The rubber filler hose in poor condition

the filler neck seal in poor condition

The metering unit return line rubber section in poor condition.

 

I've had the car since 1995 and I surmise the gradual and more recent accelerating degradation was simply wear and tear!

 

I do believe the majority of the offending smell was from the sender unit joint, evidence supported by the paint breakdown. I decided not to go down the pressure test route, as the tank look in good order, chancy you may say! I repainted the front side of the tank. I also fitted a 'fire wall' as recommended earlier in this thread with locally supplied aluminium as specified. Fiddly to fit sealed, but done and then kept there with ye olde gaffa tape, not pretty but done! Tanks back in with rubber new fittings all round. I used the superior gasket (from Moss) for the sender unit.

 

Refilled with the 20 litres of fuel (initially 5 litres just in case!) circulated for 5 minutes and car started perfectly, no injection issues, the front end must had stayed flooded.

 

All seems fine, no leaks, no smell. Last Tuesday 7th May, I had an overnight stay in Ipswich at my oldest friends, he said 'bring the TR6'. I could n't say no, nice trip good weather, hood down both ways and a great run. I do get the odd whiff of exhaust from the twin sports exhaust, but that's ok! I didn't reek of fuel, I guess the acid test is to fill the tank fully. The cars gone in for its MOT at Carlow Eng, Benfleet today, so I resisted that for now. I've asked them to check a few things, (oil leaks that's another story!) so car back later in the week.

 

Thanks for all your guidance, I'm really pleased on how things have gone.

 

I'm struggling to load the photos! I'll post this report first, then have another go.

 

Regards Trevor Hughes

[Trever the rever]

All my photos are > than 4 MB; any ideas how I can save them in lower resolution etc

 

I should know, but cant seem to fathom this one!