Petrol smell on full boost -- I can hear it, I can see it --Solved--
Turbo Mini Forums

Over the last few months I have been having a smell of petrol when I go on full boost, it started with just a whiff but has got so bad now I'm concerned.. I dont see any sign of a leak in trhe engine bay.

It only happens on full throttle, on cruise light/moderate accelleration and overrun I dont smell it. I'm thinking leak but where? The idle is the same, no leaks there. Its deffo not overfuelling..

All I can think of is the throttle spindle seals..

Any more Ideas before I rip it apart??

Terry

Edited by Turbo Tel on 20th Aug, 2009.

website:- http://www.terryhunt.co.uk

its hard to say, but on full boost mine leaks a little but nothign to worry about! although saaying that JF's throttle spindle leaked when we had our first RR and caught fire was quite funny!

Check your fuel lines. If your not useing the correct spec. Hose ie. the double walled cotton/steel reinforced wall you may find that the pie has degraded with time and has begun leaking.

If you are useing the type of fuel hose that has that poxy woven cotten braided sheaf on the outside I would look at that very very hard as the cotton hides the leak caused by degredation very very well!

Own the day

I'm using fuel injection hose.. But it did occur to me that a joint could be weak and seeping when the boost rises and the fuel regulator raises with it..

Hmm.. must work out a way to fool the regulator...wheres my bycicle pump!!

website:- http://www.terryhunt.co.uk

Choke seal perhaps?

the fuel pressure will obviously rise with boost, maybe the needle valve is being over powered and its coming out breathers or filling the plenum?

but surely the mixture would alter though, and i know you would have picked up on stray afrs already lol

are you using braided fuel hose or rubber?

braiding can often 'wick the fuel and smell through the car

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

I used a syringe and raised the pressure, no leaks seen.. Its rubber injector hose.

I don't think its the needle valve, I think I would see some AFR's changing, they are still Ok on the wideband.

The smell only comes at full boost, lasts just a few seconds then goes away.. Choke seal, throttle shaft seal or any seal that could be venting at full boost seems the best theory. I'm going to run with the bonnet off tomorrow, see if I can spot any mists and maybe if I screeech to a halt, jump out and take a look I'll catch it!!

Terry

Edited by Turbo Tel on 11th Aug, 2009.

website:- http://www.terryhunt.co.uk

I ran the car without a bonnet today, and of course I cant smell it hardly at all now!! But once it was off and I got to see around the carb in better light I noticed just a hint of yellow staining on the right side of the carb but not from the spindle area, from the top..

I whipped the dashpot off and am pretty sure that the dashpot seal was folded over in that area.. I had a new one so fitted it, I'll post the results..

How the hell that did not affect my AFR I don't know...

Terry

website:- http://www.terryhunt.co.uk

Not that...

But on my way down I-95 with a wall on my left I realised that I could hear a Pshhhhhhhhtt sound as I hit full boost.

Plus Psshhhhttt sound = smell =drop in boost

So once I stopped nailin the throttle (is there any other way of driving these things??) I realised that if I sneak up on full boost as it hits 0.6 Bar the psshhht sound happens it drops boost, and the smell happens, but keep your foot to the floor and it builds up again, thats why I didn't realise before.. I was seeing full boost.

So I have a leak that does not start till about 0.6 Bar.. I had the Pipework off from intercooler to the plenum. then removed the plenum. Buggered if I can see anything wrong..

Question is would a leak upwind of the carb cause a distinct fuel smell?? Or does it HAVE to be after the carb to make such a distinct smell?

Could I have a manifold gasket leak??

Terry

Edited by Turbo Tel on 12th Aug, 2009.

website:- http://www.terryhunt.co.uk

I wonder if you can get any UV dye, pop some of this in your tank, run up the road to get the fuel smell, then track down the leak with a UV light source? I know that the air con guys use something similar to find ACU leaks.

a bit of everything!

officially a production coordinator at a telecomunications firm, but in practice it means I design, spec, manage, sell, test, prototype, problem solve, cost, dispatch, sort out customs issues, purchasing, repairs, calibration, sales projections, appraisals, take out the rubbish, unblock the toilets, marketing, accounts, site maitnenance, ect ect ect.

currently my main design project is fibre optic based VSat data equipment for ships.


how the fuck did i manage that!!

have you blocked off the overboost valve?

Edited by Joe C on 12th Aug, 2009.

Ho ho ho, Joe replied to the wrong thread!

leaky diaphragm on the dump valve ,letting air/fuel through from the actuation pipe?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

leaky diaphragm on the dump valve ,letting air/fuel through from the actuation pipe?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Edited by Turbo Tel on 12th Aug, 2009.

website:- http://www.terryhunt.co.uk

If its a strong enough smell to get you worried i would have thought that it would be after carb IMO.

The dye is great stuff, as long as the boost pressure does not throw it all over the place. If you can get hold of it that easily then you might aswell start there! Always better to diagnose the problem before you start stripping things down!

Nothing more annoying at work than having a problem that *could* be any one of a number of things but there is no definitive answer. You normally end up with a big bill and the problem still there!

i wonder if it will make y our exhaust glow in the dark lol

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

Terry.

Does your boost gauge come from the manifold after the carb ?

In which case, have you got a split in the gauge line at the back of the gauge in your dash which could be opening up on full boost and giving you a whiff of fuel/air in the cockpit ?

Richard.

Minivanless, but reluctantly happy living with the decision. There'll be another one day.
http://www.youtube.com/profile?user=minimadmotorman#p/u

Or the boost guage itself leaking ?

Put some talcon powder on it or if you can get it NDT dye penitrant developer (talcon powder in a can).

Own the day

website:- http://www.terryhunt.co.uk

Edited by Turbo Tel on 13th Aug, 2009.

website:- http://www.terryhunt.co.uk

website:- http://www.terryhunt.co.uk

well had that in my 1380 on full boost it turned out to be blow by paST THE PISTONS AND THE SMELL WAS COMING FROM THE BREATHERS MATE SO MAY NOT BE TO GOOD.

always looking for them bigger bunches of bannanas