fuel vapour not good
Discussion
Went for a good 6 hour drive last week and after about 4 hours wife complained of petrol smells in the cabin making her feel unwell.
Nothing obvious found so carried on home.
Complete check of all the fuel lines,connections,fuel pump injectors etc but everything ok.
Removed carbon can,all blown through and clear.
All inputs/outputs blown through and clear.
Not sure if the solenoid is working or even wired into the ecu although not had any fuel smells over the last 5 years.
All refitted, spares taken as a back up on the next trip.
Went for a good drive today and same thing again,smells came back after a decent run.I was ready this time.
After a nice walk came back,removed the carbon can completely and put the breather pipe from the tank through the drain hole in the bottom of the front wing.
Everything ok but the smell still came back on the way home.
Into the garage and the breather pipe was slightly damp and smelling of petrol.
However the fuel pump was very noisy,it does seem to get very noisy after a good run.
My dilemma is this,
Is the fuel pump causing the fuel smells when it gets noisy,but no leaks etc.
Is the breather pipe damp because of fuel expansion particularly in this hot weather.
Am i missing something?
Any ideas.
Cheers
Nothing obvious found so carried on home.
Complete check of all the fuel lines,connections,fuel pump injectors etc but everything ok.
Removed carbon can,all blown through and clear.
All inputs/outputs blown through and clear.
Not sure if the solenoid is working or even wired into the ecu although not had any fuel smells over the last 5 years.
All refitted, spares taken as a back up on the next trip.
Went for a good drive today and same thing again,smells came back after a decent run.I was ready this time.
After a nice walk came back,removed the carbon can completely and put the breather pipe from the tank through the drain hole in the bottom of the front wing.
Everything ok but the smell still came back on the way home.
Into the garage and the breather pipe was slightly damp and smelling of petrol.
However the fuel pump was very noisy,it does seem to get very noisy after a good run.
My dilemma is this,
Is the fuel pump causing the fuel smells when it gets noisy,but no leaks etc.
Is the breather pipe damp because of fuel expansion particularly in this hot weather.
Am i missing something?
Any ideas.
Cheers
jod said:
Went for a good 6 hour drive last week and after about 4 hours wife complained of petrol smells in the cabin making her feel unwell.
Nothing obvious found so carried on home.
Complete check of all the fuel lines,connections,fuel pump injectors etc but everything ok.
Removed carbon can,all blown through and clear.
All inputs/outputs blown through and clear.
Not sure if the solenoid is working or even wired into the ecu although not had any fuel smells over the last 5 years.
All refitted, spares taken as a back up on the next trip.
Went for a good drive today and same thing again,smells came back after a decent run.I was ready this time.
After a nice walk came back,removed the carbon can completely and put the breather pipe from the tank through the drain hole in the bottom of the front wing.
Everything ok but the smell still came back on the way home.
Into the garage and the breather pipe was slightly damp and smelling of petrol.
However the fuel pump was very noisy,it does seem to get very noisy after a good run.
My dilemma is this,
Is the fuel pump causing the fuel smells when it gets noisy,but no leaks etc.
Is the breather pipe damp because of fuel expansion particularly in this hot weather.
Am i missing something?
Any ideas.
Cheers
Check if the fuel is returning back to the petrol tank ,I had the same problem and then found the cause.. crushed copper fuel line .Nothing obvious found so carried on home.
Complete check of all the fuel lines,connections,fuel pump injectors etc but everything ok.
Removed carbon can,all blown through and clear.
All inputs/outputs blown through and clear.
Not sure if the solenoid is working or even wired into the ecu although not had any fuel smells over the last 5 years.
All refitted, spares taken as a back up on the next trip.
Went for a good drive today and same thing again,smells came back after a decent run.I was ready this time.
After a nice walk came back,removed the carbon can completely and put the breather pipe from the tank through the drain hole in the bottom of the front wing.
Everything ok but the smell still came back on the way home.
Into the garage and the breather pipe was slightly damp and smelling of petrol.
However the fuel pump was very noisy,it does seem to get very noisy after a good run.
My dilemma is this,
Is the fuel pump causing the fuel smells when it gets noisy,but no leaks etc.
Is the breather pipe damp because of fuel expansion particularly in this hot weather.
Am i missing something?
Any ideas.
Cheers
Most external EFI pumps get noisier when its warm, look elswhere try looking around the fuel injector area and check both fuel pipes on the rear of the plenum, a sprinkle of talcum powder around unions and fittings should help you source your smell, as the fuel cap been modified/messed with? Check the fuel return back from the fuel rail to tge tank this only leaks/sweats when the car is running.
I have had similar comments from Erin Doors when we have been sitting in traffic, or on switching off in a car park. I assumed it was just that the car was running rich in such circumstances.......but it's only at low speed, not in general running. Question remains - could it just be over-fuelling? What's your mpg like? Which engine size is it?
Thanks for the info.
4.O ltr and i've never bothered checking mpg,it gets what it needs.
Just fitted a new coolant temp sensor anyway,to assist with engine management.
I have made and fitted a new fuel cap seal.
The fuel pump noise is quite excessive,you can definately hear it when driving and on tickover.
Already done a good visual on all the fuel system but when i put her back on the ramps this weekend i'll have another look.
4.O ltr and i've never bothered checking mpg,it gets what it needs.
Just fitted a new coolant temp sensor anyway,to assist with engine management.
I have made and fitted a new fuel cap seal.
The fuel pump noise is quite excessive,you can definately hear it when driving and on tickover.
Already done a good visual on all the fuel system but when i put her back on the ramps this weekend i'll have another look.
jod said:
Thanks for the info.
4.O ltr and i've never bothered checking mpg,it gets what it needs.
Just fitted a new coolant temp sensor anyway,to assist with engine management.
I have made and fitted a new fuel cap seal.
The fuel pump noise is quite excessive,you can definately hear it when driving and on tickover.
Already done a good visual on all the fuel system but when i put her back on the ramps this weekend i'll have another look.
May be worth checking the short fuel hose stub from tank to pump (surrounded by lots of Silkaflex/sealer gunk) this one seldom gets changed (pig job) 4.O ltr and i've never bothered checking mpg,it gets what it needs.
Just fitted a new coolant temp sensor anyway,to assist with engine management.
I have made and fitted a new fuel cap seal.
The fuel pump noise is quite excessive,you can definately hear it when driving and on tickover.
Already done a good visual on all the fuel system but when i put her back on the ramps this weekend i'll have another look.
if the pump draws aerated fluid it will become noisier 
If your fuel pump becomes noisy it's because its working too hard.
This can be either an issue with the supply or return elements of the fuel circuit.
Place your hand on your petrol tank when the pump starts to become noisy.
You may find at idle after a long hot run the tank is extremely hot, this is because the fuel pump is straining either to pull fuel from the tank or work against excessive pressure due to a restricted return line or a faulty fuel pressure regulator.
As the pump works harder it generates a huge amount of heat, the fuel vaporises in the pump & it cavitates.
Fuel pumps need fuel passing though to keep them cool, the pockets of vapourised fuel not only cause the pump to scream or buzz loudly but also cause the pump to run still hotter.
It's an escalating problem that can cause issues further down the fuel line directly relating to combustion, mixture & potentially a smell of fuel.
Here's how!
Fuel supply issues normally generate a weak mixture condition, this is due to an abnormal reduction in fuel pressure at the rail.
The usual suspects being a blocked fuel filter or a weak fuel pump, you will not get petrol smells with a weak mixture but the car may stall just as it would if the mixture went very rich.
Petrol smells that coincide with a very rich mixture are normally associated with a faulty fuel pressure regulator or a restriction in the return line, check also for black smoke from the exhaust that smells of raw fuel.
If the fuel pressure is too high due to a restricted return line the injectors will be overcome & leak, generating a massively over rich mixture.
If the diaphragm in the fuel pressure regulator has become split, manifold depression will not be able to act on the diaphragm to pull the spring, so the return port is not opened sufficiently to maintain the 36psi pressure at the rail.
Just like a return line restriction, a split FPR diaphragm will also cause excessive pressure in the rail at idle, & again the injectors will be overcome generating excessive fuel in the cylinders, an extremely rich mixture & a strong smell of raw fuel.
Check the diaphragm holds vacuum by using a vac tester or suck on the pipe holding the vacuum with the tip of your tongue, it should hold the vacuum indefinitely.
If you can suck on the pipe with little or no resistance or it fails to hold vacuum, the diaphragm is split.
Also check for the presence of fuel at the vac pipe itself, no fuel should be present on the vacuum side of the fuel pressure regulator, if fuel is present here the diaphragm is split.
A fuel pressure gauge is an invaluable tool for diagnosing fuel injection faults.
Conveniently on a Chimaera the rail has a service port fitted, this is nothing more complicated than a Shraeder valve.
In fact, at a push, you can even use an old school tyre gauge to check your fuel pressure at the Schraeder valve/rail.
If your fuel pressure goes high at idle followed by black smoke from the exhaust and a smell of raw petrol, it is extremely likely to have either a split diaphragm in your FPR or a restriction in the return line.
When the car is at idle it is essential the return line is free from restrictions & the FPR opens the return port fully, or the pressure in the rail will rocket, the injectors will become overloaded and too much fuel will enter the cylinders.
The engine is incapable of burning such a large amount of fuel because there simply is insufficient air present at idle.
The results are a massively rich condition indicated by black smoke from the exhaust &.....
A smell of raw fuel!!!!
Below is a classic case of a fuel return restriction from SILICONEKID343HP.
This can be either an issue with the supply or return elements of the fuel circuit.
Place your hand on your petrol tank when the pump starts to become noisy.
You may find at idle after a long hot run the tank is extremely hot, this is because the fuel pump is straining either to pull fuel from the tank or work against excessive pressure due to a restricted return line or a faulty fuel pressure regulator.
As the pump works harder it generates a huge amount of heat, the fuel vaporises in the pump & it cavitates.
Fuel pumps need fuel passing though to keep them cool, the pockets of vapourised fuel not only cause the pump to scream or buzz loudly but also cause the pump to run still hotter.
It's an escalating problem that can cause issues further down the fuel line directly relating to combustion, mixture & potentially a smell of fuel.
Here's how!
Fuel supply issues normally generate a weak mixture condition, this is due to an abnormal reduction in fuel pressure at the rail.
The usual suspects being a blocked fuel filter or a weak fuel pump, you will not get petrol smells with a weak mixture but the car may stall just as it would if the mixture went very rich.
Petrol smells that coincide with a very rich mixture are normally associated with a faulty fuel pressure regulator or a restriction in the return line, check also for black smoke from the exhaust that smells of raw fuel.
If the fuel pressure is too high due to a restricted return line the injectors will be overcome & leak, generating a massively over rich mixture.
If the diaphragm in the fuel pressure regulator has become split, manifold depression will not be able to act on the diaphragm to pull the spring, so the return port is not opened sufficiently to maintain the 36psi pressure at the rail.
Just like a return line restriction, a split FPR diaphragm will also cause excessive pressure in the rail at idle, & again the injectors will be overcome generating excessive fuel in the cylinders, an extremely rich mixture & a strong smell of raw fuel.
Check the diaphragm holds vacuum by using a vac tester or suck on the pipe holding the vacuum with the tip of your tongue, it should hold the vacuum indefinitely.
If you can suck on the pipe with little or no resistance or it fails to hold vacuum, the diaphragm is split.
Also check for the presence of fuel at the vac pipe itself, no fuel should be present on the vacuum side of the fuel pressure regulator, if fuel is present here the diaphragm is split.
A fuel pressure gauge is an invaluable tool for diagnosing fuel injection faults.
Conveniently on a Chimaera the rail has a service port fitted, this is nothing more complicated than a Shraeder valve.
In fact, at a push, you can even use an old school tyre gauge to check your fuel pressure at the Schraeder valve/rail.
If your fuel pressure goes high at idle followed by black smoke from the exhaust and a smell of raw petrol, it is extremely likely to have either a split diaphragm in your FPR or a restriction in the return line.
When the car is at idle it is essential the return line is free from restrictions & the FPR opens the return port fully, or the pressure in the rail will rocket, the injectors will become overloaded and too much fuel will enter the cylinders.
The engine is incapable of burning such a large amount of fuel because there simply is insufficient air present at idle.
The results are a massively rich condition indicated by black smoke from the exhaust &.....
A smell of raw fuel!!!!
Below is a classic case of a fuel return restriction from SILICONEKID343HP.
SILICONEKID343HP said:
Check if the fuel is returning back to the petrol tank ,I had the same problem and then found the cause.. crushed copper fuel line .
Edited by ChimpOnGas on Monday 22 July 12:19
Dave all external EFI pumps emit more noise in this heat it does not mean you have a problem 
the Fords & VW's fitted with the old K/KE Bosch Jetronic systems did this in the warmer weather this was not an indication of a knackered pump or system malfunction 
fuel temps fluctuate and there lies the problem 
the Fords & VW's fitted with the old K/KE Bosch Jetronic systems did this in the warmer weather this was not an indication of a knackered pump or system malfunction fuel temps fluctuate and there lies the problem The carbon canisters are intended to be service items & replaced, after so long the active ingredients become depleted.. IIRC they were replaced at 5 year service according to Rover / LR.
IME you will find a lot more cases of fuel hoses crushed against the chassis with cable ties than metal fuel pipes crushed (an old common 'cat-in-hell' method of attempting to tune the lucas efi)
IME you will find a lot more cases of fuel hoses crushed against the chassis with cable ties than metal fuel pipes crushed (an old common 'cat-in-hell' method of attempting to tune the lucas efi)
Sardonicus said:
Dave all external EFI pumps emit more noise in this heat it does not mean you have a problem the Fords & VW's fitted with the old K/KE Bosch Jetronic systems did this in the warmer weather this was not an indication of a knackered pump or system malfunction fuel temps fluctuate and there lies the problem
Over the last few weeks I have had this very same problem. the Fords & VW's fitted with the old K/KE Bosch Jetronic systems did this in the warmer weather this was not an indication of a knackered pump or system malfunction fuel temps fluctuate and there lies the problem Pump quiet at the start of the day & fine for an hour or more.
But just like the OP my pump starts to buzz when idling after a long hot run of 1.5 hours or more.
This is often accompanied by a ragged idle & occasional stalling which can be extremely frustrating.
The condition appeared to worsen as the fuel level falls, and is certainly worse on my car now I have a small auxiliary fuel tank.
At the same time the fuel in the tank gets extremely hot as the tank is very hot to the touch.
All this seemed to point to high fuel temps causing vaporisation.
So I fitted a fuel cooler, which worked extremely well reducing fuel temps dramatically.
But sadly it didn't solve the problem, in fact the addition restriction may well have made it worse.
Return to idle after a long hot run on petrol and it's fine for two or three minutes, then it goes way rich.
I mean black smoke my eyes are bleeding, rich.
A pressure test confirmed excessive pressure at the rail.
A quick test of the FPR confirmed it was working correctly.
So I removed & extend the return line placing it in a jerry can & the rough idle, very rich running & fuel smell immediately disappeared.
And very quickly the pump goes quite too.
So I check the pressure at the rail & sure enough it's dropped to 36/7 psi.
That's a return restriction, no question!
It's actually worse for me now I have the cooler and my new auxiliary petrol tank sits 12" higher than the original Chimaera one too because it sits on top of two LPG tanks, so I'm asking even more of my fuel pump to get that returned petrol back to the tank.
And it definitely gets worse in the hot weather, perhaps that restriction is actually a vapour lock
I'll have it sorted by the end of this week, or if I run out of gas in the south of France I'll be forced to run petrol until I find some GPL.
And I can just see myself getting stuck in one of those 40 degree traffic South of France jams I seem find every year
Edited by ChimpOnGas on Monday 22 July 13:27
Check the copper pipe return line where it exits from inbetween the body and chassis just behind the drivers seat. When I took the body off mine this return line was creased at that point. I imagine it was done when the car was built, fuel pipe positioned incorrectly and then when the body is lowered onto the chassis the body digs into the copper fuel line.
Sardonicus said:
Got the noisy pump when its hot Dave but I am also running at 3BAR but idle problems or rough running none sounds like your on the right track with your anyway
But as long as you're getting it back to the tank at a relative & sufficient rate/volume it wouldn't matter if you're running 5BAR. sounds like your on the right track with your anyway Test it.
Simply pinch the return pipe near the back of the O/S rocker cover and see what happens, pressure at the rail will rise immediately, all that pressure has to go somewhere & the injectors will be overcome.
She'll go massively rich..... smell that fuel
No traditional union or pipe leaks as such, it's just raw fuel coming out of the exhaust.
The other influencer is on a Chimaera the amps & volts at the fuel pump are marginal at best in the first place, any heat may take it over the edge.
As the pump gets hotter its internal resistance goes up, so it becomes less efficient.
My pump now has to push the returned fuel though the fuel cooler & 12" more up hill to get it back to the tank.
Perhaps it's a combination of low amps at the hot pump causing the pump to struggle, a vapour lock, & the fact my return line is now more of a challenge?
Edited by ChimpOnGas on Monday 22 July 13:44
carsy said:
Check the copper pipe return line where it exits from inbetween the body and chassis just behind the drivers seat. When I took the body off mine this return line was creased at that point. I imagine it was done when the car was built, fuel pipe positioned incorrectly and then when the body is lowered onto the chassis the body digs into the copper fuel line.
Very interesting, many thanks for the tip.ChimpOnGas said:
Very interesting, many thanks for the tip.
I`m wondering if its that Gizmo Dave you fitted ! the double non return valve (roll over valve). Since losing the carbon canister and fitting a small K&N breather (mini airfilter) next to the diff and got rid of the 044 pump ,it`s been fantastic .The ugraded pump I fitted used on Cerbera`s work fantastic ,it`s silent .
All my fuel pipes have been replaced from the tank right through to the engine and back to the petrol tank ..all nice and free. Watch out for the crap petrol connection on the tank ,it1s rubbish .
Forgot to mention I have fitted a simple ballafix valve on the vent for if I over fill to stop back siphonage.
Edited by SILICONEKID343HP on Monday 22 July 14:32
Following tip found elsewhere - Carefully check the seals around the boot. It's been found, especially during longer drives, that even a small gap will draw exhaust fumes into the boot and from there into the cabin. Not sure it applies to every car as may also depend on the existence of any vents or speaker cavities around the rear deck or behind the seats.
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