my solution to petrol smell

[blue 464]

Hi all, you may remember I recently had problems with hot starting and a petrol smell when the engine was turned of hot. The starting was resolved by resetting the float that was out of level but the occasional petrol smell remained. In the course of discussions on the forum it was suggested the pump pressure was too high and that I should fit a fuel pressure regulator, but I didn`t see how this would help with the engine off. Klaus suggested I try a permanent bleed from the pump outlet back to the tank via the spare blanked off connection on the top of the tank, this would allow back pressure caused by fuel line heating to dissapate back to the tank. I followed his suggestion, as an ex plumber I used an 8mm copper tee, with short inserts of 8mm pipe, an 8mm olive was soldered onto each pipe to act as a swage to stop the fuel pipe coming off. the branch was sealed by soldering a small piece of copper over the end and a 0,5mm hole as drilled in the end. This was inserted into the fuel oulet near the pump and connected to the tank.

result, no change in performance, the pump still shuts off when the pressure is up after initial switch on and the petrol smell from under the bonnet is gone, Thanks Klaus!

[KOY 23]

With respect to Klaus, thanks should be to Lingen, Mike, who originally proposed this on the forum.

[elvimto]

I have fitted a fuel regulator up on the left had turret and set at 2.7 psi I have the petrol or gas smell when I come back into the garage after a run so my question is if I was to run a return line to the tank would it better to put the tee in the fuel line between the regulator and the carbs and then back to the tank. Any suggestions?

[elvimto]

I have fitted a fuel regulator up on the left had turret and set at 2.7 psi I have the petrol or gas smell when I come back into the garage after a run so my question is if I was to run a return line to the tank would it better to put the tee in the fuel line between the regulator and the carbs and then back to the tank. Any suggestions?

[wilf]

So long as it had the correct 0.5mm restrictor in it, that should work.

[Hughesy]

It would be very useful (& greatly appreciated!) if someone could draw a schematic diagram of the modified system and post it on the forum? This appears to be a very good solution but I am not 100% sure of the mods you have completed. Thanks Craig

[staginhiding]

It would be very useful (& greatly appreciated!) if someone could draw a schematic diagram of the modified system and post it on the forum? This appears to be a very good solution but I am not 100% sure of the mods you have completed. Thanks Craig

Or even a pic..I'm sure there was one a little while back as I meant to save it and didn't..

[V Mad]

There is an easy way to bleed off pressure after switch off. Just fit a restricted path (eg fuel jet) between pump input and output pipes in the pump region (will only work if you dont have a pressure regulator). This will allow any pressure build up to release back down the tank pickup pipe.

Untried, but that should work.

[KOY 23]

There is an easier way as suggested by Lingen long time ago
Fit a T piece into outlet pipe from pump, run a new pipe from T to blanked off outlet on top of tank.
Pipe must have a restrictor in it, a MIG tip is ideal as it fits the pipe perfectly.
This is proven and works!
Easy to fit to a fuel regulator if mounted in boot, otherwise a new return line will be needed.

[Klaus Schlueter]

It would be very useful (& greatly appreciated!) if someone could draw a schematic diagram of the modified system and post it on the forum? This appears to be a very good solution but I am not 100% sure of the mods you have completed. Thanks Craig

Craig, here are some details (post#14):

http://www.stag.org.uk/forum/showthread.php?13150-Fuel-Characteristics-and-Vapour-Locks

KOY is correct--as I have mentioned several times here(!)-- it was Lingen who deserves the acclamation. (post #7 )
I am in the game as I have followed his intelligent advise and over the last 2 years the "petrol bleed fraction" was just me (as far as I know), although I have posted my result from time to time. The always recommended Filter King solution is perfect for a petrol pump with a too high pressure but after switching off the engine the reduced pressure is still in the petrol pipe. I will let you know in a seperate post what I found out about pressure increase after switchoff and about the amount of petrol which evaporates into the air.

Klaus