Lotus Elan

Fuel smell, this is really p***ing me off

PostPost by: NYK » Tue May 18, 2021 7:19 pm

Apologies for repeating this post but I need some serious brain power. Plus 2 nearing end of 5 year rebuild and engine was fired up for the first time this last week. The boot stinks of petrol, a small leak was noticed on the banjo now fixed. I drained the tank to fix the the banjo leak and the smell has been gradually reducing during the week, so today I shoved half a gallon in and bingo within a short time the boot stinks of petrol again. So this is what I have done.
1. Banjo washers replaced joint now dry.
2. Raised the fuel tank, slipped newspaper underneath for several hours, paper removed and bone dry.
3. Removed tank sender and put some sealant on both sides of rubber seal, unit replaced.
4. All hoses to the filler are new and the filler cap is new.
5. The two breathers are connected together with new hoses they run to a 4 way connector, with one arm going to a connector on the filler neck (this connector is brazed in place) the 4th arm of the connector connects to the breather pipe which runs up to the roof then out into the wheel arch (this is a copper pipe, ie I have done the fuel tank vent mod as recommended elsewhere on this forum.
I should also mention that I have a new electric pump in boot, all connections are dry.

There are no signs of any wet fuel anywhere, so where the hell are the fumes coming from?
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PostPost by: mbell » Tue May 18, 2021 7:58 pm

I have similar smells but no leaks. I put it down to hoses and connections being permeable to modern fuels vapors.

What hose/connector material have you used? How well sealed are the hose connections?
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PostPost by: NYK » Tue May 18, 2021 8:29 pm

mbell wrote:I have similar smells but no leaks. I put it down to hoses and connections being permeable to modern fuels vapors.

What hose/connector material have you used? How well sealed are the hose connections?

They’re all fuel hoses both for the filler and the vent hoses, all are tight push fits with good quality stainless steel jubilee clips.
A faint smell of fuel would be one thing, but this is a really strong smell like you’d sloshed petrol around.
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PostPost by: Billmack » Tue May 18, 2021 10:24 pm

Bring it to someone who has s smoke generator to find the leak. Popular diagnostic tool on modern cars
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PostPost by: Matt Elan » Wed May 19, 2021 7:39 am

A couple of suggestions to try to track it down:
Have you tried blocking the vent pipe to see if that’s causing the smell?
Is the smell worse inside the boot than around or below the car, if it is it must be coming from the tank itself not the banjo onwards (which would include the pipe work from the banjo to the fuel pipe
I assume you’ve checked all pipe clips are tight
Did you get your petrol pipes from a reputable source not eBay so you have some certainty that they are fuel proof?
Any signs of a leak from the pipe running under the car in the chassis to the carbs?
Hths
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PostPost by: NYK » Wed May 19, 2021 8:42 am

Matt Elan wrote:A couple of suggestions to try to track it down:
Have you tried blocking the vent pipe to see if that’s causing the smell?
Is the smell worse inside the boot than around or below the car, if it is it must be coming from the tank itself not the banjo onwards (which would include the pipe work from the banjo to the fuel pipe
I assume you’ve checked all pipe clips are tight
Did you get your petrol pipes from a reputable source not eBay so you have some certainty that they are fuel proof?
Any signs of a leak from the pipe running under the car in the chassis to the carbs?
Hths
Matt

Hi Matt,
Some good thoughts. All pipe work to carbs is new and when I was under the car this week there were absolutely no signs of petrol and no smell of petrol. Clips are certainly tight, I would likely have bought hoses from eBay so I think you are correct these are the next things to eliminate. Today I will remove the hoses on the filler and blank the vents. The smell is most definitely strongest in the boot so it would seem that the culprit lies there.
Nic
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PostPost by: nmauduit » Wed May 19, 2021 9:17 am

I'm not sure I've seen if you've commented on the tank in previous threads : is it new, has it been tested for leaks prior to installation?

Before changing anything else I would attempt to check (double check?) everything to find out the actual source of the stink, and if all else has been unsuccessful I would eventually take out the tank, slightly pressurise it with compressed air and spray it with soapy water (esp. the seams and underneath) looking for cracked welds or corrosion pinholes.
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PostPost by: NYK » Wed May 19, 2021 10:06 am

Tank removal is certainly on my list but clearly would like to eliminate as much as I can before doing that. Filler hose is the prime suspect today, just removed and is smells strongly of petrol even when ends are blocked off. Just ordered new hose from Paul Matty. Tank inlet is currently ‘bunged’ and I’m venting the boot area, hopefully the petrol vapour with evaporate during the course of the day.
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PostPost by: nmauduit » Wed May 19, 2021 12:22 pm

if the smell is strong (agreed, this is subjective) it is not just fumes leaking from a bad venting hose, there must be liquid fuel evaporating somewhere...
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PostPost by: HCA » Wed May 19, 2021 12:37 pm

Have you followed Matt's advice on blocking up the outside vent pipe? At the same time, I would add to seal off the filler cap as well and see if anything has changed.

I have to admit that in this modern day where fuel smells do not exist, I am very sensitive to smells now, even to the extent of driving behind someone in a well maintained older petrol car! With my +2, the very fact of having a single pipe venting to atmosphere was nauseous until I allowed the tank to pressurise itself with a TPV.
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PostPost by: NYK » Wed May 19, 2021 4:03 pm

The rubber connector on the filler is now removed and absolutely sticks of petrol having sat in fresh air for half a day. It could of course be that I have more than one issue giving rise to the smell but this connector could easily be the sole culprit. A new hose will be here and fitted tomorrow. If the new connector hose does not totally resolve the problem then I will work through the list as Matt suggests. It’s always sensible to change one variable at a time. I have to confess that the filler hose I’ve just removed was a silicone hose I put on, I now understand that silicone is described as porous to fuel, should have done my homework!
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PostPost by: HCA » Wed May 19, 2021 4:11 pm

By ‘rubber connector’, do you mean the large hose between filler neck and tank inlet? Yes, replace it if it is silicone! Put in the correct one, line it up so it fits well and tighten the clips - you may well solve most of your complaint. A presdure vent on the vent pipe and it will be like sitting in a rose bed :D
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Macan - hers
Felicia Pickup - my favourite
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PostPost by: NYK » Wed May 19, 2021 6:09 pm

HCA wrote:By ‘rubber connector’, do you mean the large hose between filler neck and tank inlet? Yes, replace it if it is silicone! Put in the correct one, line it up so it fits well and tighten the clips - you may well solve most of your complaint. A presdure vent on the vent pipe and it will be like sitting in a rose bed :D

Yes correct, large hose on filler. When you mention pressure vent on vent pipe, exactly what fitment are you proposing?
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PostPost by: Nickp » Thu May 20, 2021 9:02 am

Hi.I had the same problem.In the end I changed the complete fuel cap,I bought direct from the original suppliers who after all these years are still trading.
Smell gone.
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PostPost by: HCA » Thu May 20, 2021 9:10 am

NYK wrote: When you mention pressure vent on vent pipe, exactly what fitment are you proposing?


I am only with an iphone at minute, but google 'TPV8' - it is a valve that allows the tank to pressurise itself up to a certain limit that brings your tank up to modern day standards. A bit pricey maybe, but does the job. It will only work though if all your other connections - including filler cap - are airtight.
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Macan - hers
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