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Fuel smell through induction hose in boot? - Induction/Turbo/Chargecooler/Manifold/Exhaust - The Lotus Forums Jump to content
eeyoreish

Fuel smell through induction hose in boot?

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Recently replaced the tank vent pipes on my 1990 N/A but have now noticed a strong smell of fuel in the rear boot of my car after running the engine.

I've traced it to the large air intake hose that runs from the air box, through a large 'barrel' air box under the RH side shelf and terminates just above the battery. This hose is basically venting fuel vapour from the open carbs, through the air filter and back into the boot.

I might be missing something but how is the system supposed to prevent this happening? Should there be something to stop the vapour getting through? I don't believe my car has (or should have) a charcoal filter?

Also, what is the purpose of the small white canister in the yellow pipe that runs from the spigot on the air box to underneath the car? Is this some form of filter too?

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The small canister on top of the fuel tank is a purge pump to suck air from the airbox when the engine is hot and has just been turned off. The stops that embarrassing 30 seconds cranking when you try to start the bloody thing after filling up at a petrol station. The pump will by now  be dead as it runs until the coolant temp drops to a set level so burns its self out in the end.  There is a write up on excel.net re fitting a new motor to the pump ( open it up time) and a timer relay so it runs for  a set time then cuts out regardless of coolant temp.

 

The air intake set up is stock and the round barrel is I think to damp noise from the intake.   My car 88 n/a  has new tanks, pipes etc and  the garage still wiffs of fuel after its been put away.  Joy of carbs I guess. However check the tanks as well if they have not been replaced already.

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I'm pretty sure the tanks are ok at the moment as there's no fuel odour around them or under them in the foam. The vent pipes were well rotted so I replaced all those a few months ago.

The purge pump is interesting... I haven't noticed any activity from it so youre right that it's probably dead. I'll check out the Excel site (I used to have one so don't mind rekindling that relationship!). Logically the lack of a working pump would mean that all of the fuel vapour is venting into the boot, hence (perhaps) my problem...

Thanks for the info and the steer towards the pump fix!

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The replacement pump motor is not too expensive from Maplin ( £7 ish I think) .  If yours was working you would hear it drone away when you turn the engine off after a run.  The casing is a pain to split apart and I think in the end I carefully cut it open with a saw at the join then rebonded it back together.

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Thanks. Off to Maplin's I go then!

Did you wire yours through a timer or just as original?

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I did the timer  route as it will run for ages until the coolant in the curved ally  pipe that runs over the alternator has dropped in temp after the engine is turned off.

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Ok, so I'm having some problems here.

I've got a new motor for the pump and changing it over seems simple enough.

However, when I removed my pump I discovered that it was disconnected, no doubt because it's broken! Problem is, I don't seem to have a spare connector on the loom to suit the one on the pump 'tail' (1 blue, 1 brown wire into a twin female spade connector).

I do have some spare loom connectors in that area but not compatible with the motor tail...

Can anyone tell me at least what colour wires I'm looking for on the 'missing' part of the loom?

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You don't want to worry about trivial things like that..................Its a F&^%ing Lotus  what did you expect.

 

From memory and I will check  and photo for you the colours don't match up.  The parts manual should show the swap over of colours but I will go and get you a pic now.

 

The colours you are looking for are purple with pink stripe and purple with slate stripe.  The connector from the loom  is as in the r/h side of the pic ie with the purple etc wires  (ignore the red tape on one you wont have that).  The other end from the motor is brown and blue (????) but the terminals are mine for wiring in the relay.  Mine us set up so I if the relay packs up I can simply delete it from the circuit and plug the original circuit back together with original terminals. 

 So Purple with slate goes to blue on the motor and purple with pink goes to brown.    The worst that will happen I think is the motor runs backwards. 

I don't think anyone did ever decide if it was suck or blow on the motor.

post-1261-0-06061100-1431798515.jpg

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Great, thanks Malcolm! I'll have another rummage amongst the wires tomorrow and see if I can locate the missing connections.

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Great, thanks Malcolm! I'll have another rummage amongst the wires tomorrow and see if I can locate the missing connections.

 

Finally located the missing connector and plugged it into my re-motored purge pump.

 

The pump now runs when the engine is turned off hot, sucking from the airbox and blowing down through the pipe that exits under the car.

 

Problem is I still have a smell of petrol coming through the air intake into the boot  :(

 

Is this normal? I guess only fellow N/A owners will know as I believe the turbos all have a different intake system.

 

I thought about doing the 'ram air' conversion so that the intake is direct from outside but on that side there isn't a pipe connection behind the quarter-light, just an intake vent...

 

Anyone done it on a Stevens N/A??

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I don't think you can as there's no noise suppressor to bypass.

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I don't think you can as there's no noise suppressor to bypass.

 

Ah, of course Bibs. you're a former N/A owner!

 

There is a large (8" diameter ish) 'barrel' shaped canister in the intake hose on top of the RH tank, which is just lined with mesh/foam so I assume that's some form of intake noise suppressor? 

 

Not sure what the effect of removing this and just routing the intake hose to the vent behind the quarterlight would be? More intake noise maybe but any downsides??

 

Just don't like the fuel smell in the boot, especially as the intake exits directly above the battery  :dizzy:

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Not sure what the effect of removing this and just routing the intake hose to the vent behind the quarterlight would be? More intake noise maybe but any downsides??

 

 

A common modification and, I believe, standard on later cars. I did it on mine. I'm not overly keen on the additional noise. Some may prefer something a little more subtle.

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