Single fuel tank
Discussion
Evening all,
Has anyone removed one of the fuel tanks to just leave the drivers side one? Ive read a few tank related posts tonight and many people seem to have difficulty filling both tanks with modern fast fuel pumps, ive also had issues with parking at an angle so the fuel runs into the 1st tank and overflows out the back (ruining a new tarmac drive at a B&B), hot weather seems to do the same with expansion. I figured it may not be as well balanced but the second tank probably doesn't fill most times anyway and since it overflowed i usually only put small amounts of fuel in.
I can't remember because the body has been off for so long but it may even give better access to the rear brakes?
All the best.
Jon
Has anyone removed one of the fuel tanks to just leave the drivers side one? Ive read a few tank related posts tonight and many people seem to have difficulty filling both tanks with modern fast fuel pumps, ive also had issues with parking at an angle so the fuel runs into the 1st tank and overflows out the back (ruining a new tarmac drive at a B&B), hot weather seems to do the same with expansion. I figured it may not be as well balanced but the second tank probably doesn't fill most times anyway and since it overflowed i usually only put small amounts of fuel in.
I can't remember because the body has been off for so long but it may even give better access to the rear brakes?
All the best.
Jon
No not from the filler, from the small vent/ overflow pipe in the filler neck which runs round the boot and exits near the passenger side wheel. It is the filling that is the main problem as the tanks have a small joining pipe at the bottom and a large 2" ish pipe at the top, because of the high fuel pump rate of modern petrol stations the two tanks don't seem to equalise from the bottom, they appear to overflow from one tank to the other through the top connector which is at a far slower rate than fuel is going in at.
The overflowing out the back is (i assume) caused by the top of the tanks being fairly high in relation to the filler neck vent/ overflow, when parked on an angle the fuel stays level and ends up going back up the filler. I would think that as the injection system uses a fuel return line the tank could be sealed with no need for a vent?
Modern fuel tanks tend to be fairly flat to keep the centre of gravity down, this means they are sat much lower than the filler with no chance of overflowing. Am i right in thinking that the more modern TVRs had a top filler cap in the boot? Again very little chance of overflowing.
I am only weigh up my options before i put the body back on, it would also be one less thing to refurbish etc. if i only fitted one (lazy).
Regards
Jon
The overflowing out the back is (i assume) caused by the top of the tanks being fairly high in relation to the filler neck vent/ overflow, when parked on an angle the fuel stays level and ends up going back up the filler. I would think that as the injection system uses a fuel return line the tank could be sealed with no need for a vent?
Modern fuel tanks tend to be fairly flat to keep the centre of gravity down, this means they are sat much lower than the filler with no chance of overflowing. Am i right in thinking that the more modern TVRs had a top filler cap in the boot? Again very little chance of overflowing.
I am only weigh up my options before i put the body back on, it would also be one less thing to refurbish etc. if i only fitted one (lazy).
Regards
Jon
Another factor is that once it starts to siphon out then its a PITA to stop...I nearly burnt down an ancient Belgium forest..
I know the US cars had a rollover valve, however there is a factor of open and closed loop fuel systems....You should have a non-vented fuel cap.
One tank only holds around 30 litres so just over 100 miles on a full tank....
The 280i had a 2" connecting hose compared to the smaller hose on the 350i....I agree that the balance pipe is way too small...
I know the US cars had a rollover valve, however there is a factor of open and closed loop fuel systems....You should have a non-vented fuel cap.
One tank only holds around 30 litres so just over 100 miles on a full tank....
The 280i had a 2" connecting hose compared to the smaller hose on the 350i....I agree that the balance pipe is way too small...
Always had an issue with filling my 400SE with fast flow pumps ... they put too much air into the tank with the fuel that causes an air bubble. if pulling the trigger slowly, its possible that the pump will time out before the tanks are full. parking at an angle has, in the past meant I get anything from 50 litres (if the angle is towards the passenger side) to around 20 (if angling towards the filler cap).
I visited an Esso garage in the south east recently and they had new digital pump nozzles...Haven't seen them anywhere else yet, There is a fast fill and a slow fill that you select on the actual hand part...(There was also an attendant...Blimey that takes me back)...
Fast fill was fine for 25 litres but after that slow fill was in order...
One thing I did notice was that the nozzle went all the way in to the filler neck and there was no pump shut off due to gas build up..Technology is a wonderful thing...Until someone drops an EMP device on us...
Fast fill was fine for 25 litres but after that slow fill was in order...
One thing I did notice was that the nozzle went all the way in to the filler neck and there was no pump shut off due to gas build up..Technology is a wonderful thing...Until someone drops an EMP device on us...
I think Mr Zig is in the Matrix. the EMP is only in the Fast and Furious. The rozzers got me with there emp gun when i had my skyline r34 nismo spec II back in the day. now i just wait till the pump stops, go and get wallet out of center console, put another tenner in, 40 Quid puts the guage near the top.
mrcrappy said:
It is the filling that is the main problem as the tanks have a small joining pipe at the bottom and a large 2" ish pipe at the top...
You know, fuel is a very "thin" liquid and usually has no problem filling the left hand tank through these pipes.I too fill on fast until the first "click" then after that squeeze it in gently, never have a problem, only the very occasional splashback if too enthusiastic.
Yeah you don't want to fill right up unless you know you're going to do at least 15 miles to avoid overflow problems.
I think this was a problem when the cars were new (I've seen it referred to in magazine articles). The design isn't great... I no longer 'brim' my cars as they will overflow through the vent if I do; especially if you park at an angle, corner enthusiatically or if the ambient temperature is high.
Fuel tank design should allow for an expansion volume above the fuel that stops 'overfilling' and allows for heat expansion; I'm pretty sure our cars do not have that; or if they do the volume is not big enough, especially for modern high volativity fuels.
I don't think the 'overflowing' problem is related to the balancing between the two tanks. My RH tanks ('86 cars) have an internal link pipe connecting the fill spigot to the 2" link pipe to the LH tank. The internal link pipe has holes in it; but it means that the LH tank is fed directly from the filler so you are not relying on the lower balance pipes to equalise the fill level - I suspect with a 'fast fill' pump that the LH tank fills before the RH tank. Removing one of the tanks won't help, especially as you'd have to keep the fuel level high as otherwise you'd be running out of fuel all the time!
Fuel tank design should allow for an expansion volume above the fuel that stops 'overfilling' and allows for heat expansion; I'm pretty sure our cars do not have that; or if they do the volume is not big enough, especially for modern high volativity fuels.
I don't think the 'overflowing' problem is related to the balancing between the two tanks. My RH tanks ('86 cars) have an internal link pipe connecting the fill spigot to the 2" link pipe to the LH tank. The internal link pipe has holes in it; but it means that the LH tank is fed directly from the filler so you are not relying on the lower balance pipes to equalise the fill level - I suspect with a 'fast fill' pump that the LH tank fills before the RH tank. Removing one of the tanks won't help, especially as you'd have to keep the fuel level high as otherwise you'd be running out of fuel all the time!
Until yesterday, a fill to the click always resulted in 3/4 of a tank - no matter how much I feather the gun. Never normally let the gauge go below 1/4, so it's usually less than £30 of super to fill to that 3/4 level.
Yesterday morning, decided on a last minute "drive it day" jaunt. Left home with the gauge about 3 or 4mm above half full. By the time I got into Rye, the gauge was floating between "0" and a few mm above. That's when I found that the nearest fuel station was 20 minutes away in Hastings... Got there with the gauge still reading nigh-on empty. Filled up and I mean filled up (even sloshed out, due to a lazy cut-out) - never managed to get that much in before, but it was 32 litres! Gauge showed "full" for the first time since I've had it.
Anyway, another spirited drive home and the gauge was still reading above 3/4. Very odd. The run back from Rye to Maidstone is twisty and bumpy (in places), so any equalising of the tanks should have happened, yet the gauge never showed this. I can only surmise one thing or another - either the tanks are half full when the gauge shows empty, or I am running off of one tank.
Yesterday morning, decided on a last minute "drive it day" jaunt. Left home with the gauge about 3 or 4mm above half full. By the time I got into Rye, the gauge was floating between "0" and a few mm above. That's when I found that the nearest fuel station was 20 minutes away in Hastings... Got there with the gauge still reading nigh-on empty. Filled up and I mean filled up (even sloshed out, due to a lazy cut-out) - never managed to get that much in before, but it was 32 litres! Gauge showed "full" for the first time since I've had it.
Anyway, another spirited drive home and the gauge was still reading above 3/4. Very odd. The run back from Rye to Maidstone is twisty and bumpy (in places), so any equalising of the tanks should have happened, yet the gauge never showed this. I can only surmise one thing or another - either the tanks are half full when the gauge shows empty, or I am running off of one tank.
I think a conclusion is that the fuel sender is pants and we shouldn't rely on it...I keep mine at just over half unless im going 100 miles +...This is what I was going to have fitted in the 280i...
https://www.google.co.uk/url?sa=t&rct=j&q=...
https://www.google.co.uk/url?sa=t&rct=j&q=...
mrzigazaga said:
This is what I was going to have fitted in the 280i...
We use those - would have been no use in a Wedge. It's a series of reed switches which vary the resistance in steps - in our case 10 of them over 250mm (length vs steps is a constant ratio). Makes for quite a course reading - which is okay for the equipment we produce, but not a car. You'd also need a gauge calibrated especially - or, like we do, have a microprocessor reading the resistance and outputting to a fully electronic dash...Edited by eesbad on Monday 24th April 13:29
I did wonder whether i could move the overflow in the filler neck and re route it back to the tank, assuming i never filled the tank to the top to leave an air gap for heat expansion i guess i would be ok? Failing that a pressure relief valve in the top of the tank but to be honest i cannot imagine enough pressure would build up to do any damage. Back when i found this issue i used to push one of these in the rear overflow and in never blew out or leaked. 
I Suppose while they are both out i could have a bigger bottom connector welded to each tank, i cannot for the life of me remember how much clearance there is down there though, seem to remember it being tight.
I Suppose while they are both out i could have a bigger bottom connector welded to each tank, i cannot for the life of me remember how much clearance there is down there though, seem to remember it being tight.
I have had the same problem on my old Wedge which Eesbad now has filled up to the top which took ages then when I was on a slight slope petrol came out of overflow
It seems even worse on the Gredge takes forever to fill up but gauge only ever reads 3/4 full I am tempted to have a can of petrol in the boot till it runs out to see how far it will go before I run out if that makes sense
It seems even worse on the Gredge takes forever to fill up but gauge only ever reads 3/4 full I am tempted to have a can of petrol in the boot till it runs out to see how far it will go before I run out if that makes sense
Edited by billynobrakes on Monday 24th April 17:56
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