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80 Fuel tank breather
- Thread starter Paul
- Start date
Well I swapped out my fuel filter tonight. Never actually seen much dirt in a filter. But this one actually had solids in it. Not in very good order at all. Fired it up and it was rather smokey for a bit. Put filler cap back on this time and went for a blast. Well it keeps getting better. Engine feels much free-er. Actually hit 80 at one point. It is sounding better to. Much more like the roar of a 4.2 straight six.
The wiring for the water trap sensor is stuffed though. Been wound round and round by some clusterflop.
Chris
The wiring for the water trap sensor is stuffed though. Been wound round and round by some clusterflop.
Chris
Toby
Active Member
- Joined
- Feb 26, 2010
- Messages
- 86
Adrian,
If you go for a Walbro then fit it as close to the tank end as you can. There is a useful space above the big centre exhaust box heat shield, though you'll need to make up your own bracket - try to fix this to the chassis rather than the body, to reduce the noise and vibration transmitted into the cabin (though the new pumps might be better in this respect, both mine are the old type).
Bear in mind that a pusher pump is really fixing the symptom not the cause - a worn lift pump section in the injection pump or air leaks in the fuel system. However it is cheaper than stripping down the injection pump to fix a tired lift pump and will much reduce or eliminate any air leaks (it might even turn them into fuel leaks).
I fitted one to cure a tired lift pump on a 250K mile 80, the other on an overland car to help supply fuel from the long range rear tank - not only was the length of pipe from the tank pickup to the IP greater, the fuel from both tanks had to go through a changeover valve which was potentially a little restrictive, so I added the pump after the valve as a belt and braces solution.
A pusher pump would probably help overcome the effect of a blocked tank cap breather, though Rob's fix would definitely be easier and cheaper...
On the positive/negative pressure question, I can't see how you'd get positive pressure in the tank without (a) the relief valve being blocked and (b) a really dramatic temperature rise. A as I can see a slight vacuum is normal.
All the best,
Toby
1990 HDJ80 UK 'some minor bodywork imperfections'.
1994 HDJ80. Ditto.
If you go for a Walbro then fit it as close to the tank end as you can. There is a useful space above the big centre exhaust box heat shield, though you'll need to make up your own bracket - try to fix this to the chassis rather than the body, to reduce the noise and vibration transmitted into the cabin (though the new pumps might be better in this respect, both mine are the old type).
Bear in mind that a pusher pump is really fixing the symptom not the cause - a worn lift pump section in the injection pump or air leaks in the fuel system. However it is cheaper than stripping down the injection pump to fix a tired lift pump and will much reduce or eliminate any air leaks (it might even turn them into fuel leaks).
I fitted one to cure a tired lift pump on a 250K mile 80, the other on an overland car to help supply fuel from the long range rear tank - not only was the length of pipe from the tank pickup to the IP greater, the fuel from both tanks had to go through a changeover valve which was potentially a little restrictive, so I added the pump after the valve as a belt and braces solution.
A pusher pump would probably help overcome the effect of a blocked tank cap breather, though Rob's fix would definitely be easier and cheaper...
On the positive/negative pressure question, I can't see how you'd get positive pressure in the tank without (a) the relief valve being blocked and (b) a really dramatic temperature rise. A as I can see a slight vacuum is normal.
All the best,
Toby
1990 HDJ80 UK 'some minor bodywork imperfections'.
1994 HDJ80. Ditto.
Hi Toby
Thanks for that. Very useful.
My truck is actually really well. Thankfully. Just enjoy tinkering and checking and replacing things as or before they come up. If the walbro helps the current set up last even longer then it'll be a good thing in my world.
Regards
Thanks for that. Very useful.
My truck is actually really well. Thankfully. Just enjoy tinkering and checking and replacing things as or before they come up. If the walbro helps the current set up last even longer then it'll be a good thing in my world.
Regards
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Toby
Active Member
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- Feb 26, 2010
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- 86
Hi Adrian,
If ain't broke...
I wouldn't add a Walbro unless you actually have a problem to solve, the old ones are quite noisy and you're adding another component capable of failing and stopping your truck.
All the best,
Toby
1990 HDJ80 UK 'some minor bodywork imperfections'.
1994 HDJ80. Ditto.
If ain't broke...
I wouldn't add a Walbro unless you actually have a problem to solve, the old ones are quite noisy and you're adding another component capable of failing and stopping your truck.
All the best,
Toby
1990 HDJ80 UK 'some minor bodywork imperfections'.
1994 HDJ80. Ditto.
OK as I have some weird idle problems which I posted on the TLOC forum http://www.tlocuk.co.uk/forums/viewtopi ... 2eff0b9afd
As you can see I have pretty much covered the bases, one thing I did investigate was the fact that when I bought the car it had a OE cap that was looking rather grotty and I treated the car to a new shiny locking one. After awhile I noticed a 'hiss' when opening the cap. I was unsure if this was air being sucked in or blown out. I drove the car without the cap and it had zero effect on it's performance and it drove as well as it always has. I checked the breather which is under the car and stuffed in the rear crossmember you know where all the water and crap gets? Well there is a breather flap there and it is pretty much the same as the ones on the axles and works in the same way, the one way valve is normally closed and when excessive pressure builds in the tank it is vented out however, please note that a certain amount of pressure is need to overcome the action of the spring within the valve hence the tank will have some positive pressure. If the car hits cold water the tank air acts the same as a chilled axle, the air contracts the pressure falls and the flap closes under the action of the spring. The amount of pressure needed to open even my dirty old valve was minimal, even allowing for a weak spring it is a very low pressure indeed, so yes the tank is at positive pressure but not much, I have to assume the old cap was faulty and letting air in and out because nothing was going in or out of the breather pipe.
My valve was caked with crud and no amount of cleaning was going to help, I simply cut of the valve and extended the breather up into the engine bay with a plastic fuel filter, this is a temporary measure until my breather manifold is ordered. The hissing when I open the cap is now gone and there is still no detectable change in performance or MPG which sits around 27/27 MPG with no effort.
I hope that helps?
regards
Dave
As you can see I have pretty much covered the bases, one thing I did investigate was the fact that when I bought the car it had a OE cap that was looking rather grotty and I treated the car to a new shiny locking one. After awhile I noticed a 'hiss' when opening the cap. I was unsure if this was air being sucked in or blown out. I drove the car without the cap and it had zero effect on it's performance and it drove as well as it always has. I checked the breather which is under the car and stuffed in the rear crossmember you know where all the water and crap gets? Well there is a breather flap there and it is pretty much the same as the ones on the axles and works in the same way, the one way valve is normally closed and when excessive pressure builds in the tank it is vented out however, please note that a certain amount of pressure is need to overcome the action of the spring within the valve hence the tank will have some positive pressure. If the car hits cold water the tank air acts the same as a chilled axle, the air contracts the pressure falls and the flap closes under the action of the spring. The amount of pressure needed to open even my dirty old valve was minimal, even allowing for a weak spring it is a very low pressure indeed, so yes the tank is at positive pressure but not much, I have to assume the old cap was faulty and letting air in and out because nothing was going in or out of the breather pipe.
My valve was caked with crud and no amount of cleaning was going to help, I simply cut of the valve and extended the breather up into the engine bay with a plastic fuel filter, this is a temporary measure until my breather manifold is ordered. The hissing when I open the cap is now gone and there is still no detectable change in performance or MPG which sits around 27/27 MPG with no effort.
I hope that helps?
regards
Dave
Julian Voelcker
Well-Known Member
- Joined
- Mar 5, 2010
- Messages
- 313
Just to clear up some confusions...
The breather on the tank is a one way expansion valve designed to counter any pressure build up in the tank which is most commonly caused by the heating of the fuel and air in the tank leading to an increase in volume during the day.
The breather in the cap is also a one way valve, but to allow air into the tank to replace the fuel being taken out of it whilst driving or to couner drops in pressure as the fuel and air in the tank cools and shrinks in volume.
Under normal driving conditions the tank experiences negative pressure as the fuel comes out of the tank. Yes some fuel is returned to the tank but obviously only a fraction of what comes out of it.
Now I have had hissing from my fuel cap for ages and have tried stripping and cleaning the valve in my cap a couple of times but it made no difference. I have also often run without the cap done up properly, but it made little difference to the performance so I wasn't that fussed.
However the other day I thought that I would treat myself to a new cap in a last attempt to prevent the hissing, but it made no difference so I lost patience and drilled a 2mm hole right throught the middle of the cap - I don't get any hissing now
.
On the walbro pump front it tends to make a reasonable difference to most trucks and a massive difference on others. It appears to take the strain off the IP making it more lively, particularly at higher revs and also climbing steep hills. We always fit the pump where Toby suggests but mount it on anti vibration mounts so that we don't get any noise issues and it can be wired in easily to come on with the ignition.
The breather on the tank is a one way expansion valve designed to counter any pressure build up in the tank which is most commonly caused by the heating of the fuel and air in the tank leading to an increase in volume during the day.
The breather in the cap is also a one way valve, but to allow air into the tank to replace the fuel being taken out of it whilst driving or to couner drops in pressure as the fuel and air in the tank cools and shrinks in volume.
Under normal driving conditions the tank experiences negative pressure as the fuel comes out of the tank. Yes some fuel is returned to the tank but obviously only a fraction of what comes out of it.
Now I have had hissing from my fuel cap for ages and have tried stripping and cleaning the valve in my cap a couple of times but it made no difference. I have also often run without the cap done up properly, but it made little difference to the performance so I wasn't that fussed.
However the other day I thought that I would treat myself to a new cap in a last attempt to prevent the hissing, but it made no difference so I lost patience and drilled a 2mm hole right throught the middle of the cap - I don't get any hissing now
.On the walbro pump front it tends to make a reasonable difference to most trucks and a massive difference on others. It appears to take the strain off the IP making it more lively, particularly at higher revs and also climbing steep hills. We always fit the pump where Toby suggests but mount it on anti vibration mounts so that we don't get any noise issues and it can be wired in easily to come on with the ignition.
Julian Voelcker
Well-Known Member
- Joined
- Mar 5, 2010
- Messages
- 313
Chris said:
If you are patient you can dig out around where the wires enter the sensor and solder the wires back on and then secure in place with something like Araldite.
Just a thought guys on the pusher pump, without wishing to pull to far off topic but...........the fuel heater on the 80 IIRC works when it detects excessive vacuum from the pump trying to pull through cold (heavy) fuel, is that correct?
If that is right then fitting a 'pusher' will stop that from working in very cold weather, am I right on this or will we (I am going to fit one) need to fit in a temperature sensitive switch?
regards
Dave
If that is right then fitting a 'pusher' will stop that from working in very cold weather, am I right on this or will we (I am going to fit one) need to fit in a temperature sensitive switch?
regards
Dave
Toby
Active Member
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- Feb 26, 2010
- Messages
- 86
Dave,
I think you're right. If so, a pusher pump equipped 80 won't turn on it's fuel heater until the fuel lines are completely waxed up (i.e. the pusher pump can't create any pressure at the filter).
I'd guess if the temperature has fallen far enough for the lines to be waxed this badly, then the heater is irrelevant anyway? Sure, it might melt enough at the filter housing to start the engine (if the filter to engine hose and IP itself aren't blocked) but even then it won't run for long.
In theory, if the fuel lines are only partially waxed then pusher pump will still be able to pump some fuel through anyway mitigating the need for heating. Once running the IP itself will start to heat the fuel.
I've had pusher pumps on both 80s since late 2006 and haven't had any cold starting issues, though in fairness the climate here in Surrey isn't exactly extreme;-)
All the best,
Toby
I think you're right. If so, a pusher pump equipped 80 won't turn on it's fuel heater until the fuel lines are completely waxed up (i.e. the pusher pump can't create any pressure at the filter).
I'd guess if the temperature has fallen far enough for the lines to be waxed this badly, then the heater is irrelevant anyway? Sure, it might melt enough at the filter housing to start the engine (if the filter to engine hose and IP itself aren't blocked) but even then it won't run for long.
In theory, if the fuel lines are only partially waxed then pusher pump will still be able to pump some fuel through anyway mitigating the need for heating. Once running the IP itself will start to heat the fuel.
I've had pusher pumps on both 80s since late 2006 and haven't had any cold starting issues, though in fairness the climate here in Surrey isn't exactly extreme;-)
All the best,
Toby
Rob
Well-Known Member
I suspect this will be an issue if you use UK fuel in Siberia during winter as local diesel usually has the appropriate additives to stop it from freezing.
EDIT: you can always light a fire under the truck, I've been told it works really well
EDIT: you can always light a fire under the truck, I've been told it works really well
This issue of waxing used to be a big problem in the UK but as mentioned a lot of additives are now in use however, the waxing rarely blocks the fuel line, it is when it meets the fuel filter medium along with particles of water plus any water that is lying in the separator at the bottom.
Having driven HGV's or as they are now called LGV's for quit awhile I can confirm that changing the fuel filter on a non running engine and pouring in some parafin will usually get you up and running, either way I might fit a 'fuel heat' switch or some kind of thermo switch.
Oh and the idea about lighting fire under the fuel tank is brilliant I would recommend it on those plastic tanks because the heat gets through real quick
regards
Dave
Having driven HGV's or as they are now called LGV's for quit awhile I can confirm that changing the fuel filter on a non running engine and pouring in some parafin will usually get you up and running, either way I might fit a 'fuel heat' switch or some kind of thermo switch.
Oh and the idea about lighting fire under the fuel tank is brilliant I would recommend it on those plastic tanks because the heat gets through real quick
regards
Dave
Paul
Well-Known Member
Siberia does have a special diesel that is sold in winter but it is extremely crap. The locals will not usually switch off engines in an effort to keep them going and I've seen lots of solutions to waxing including routing exhausts through the middle of fuel tanks to hanging a lit 12v bulb in the tank to keep it warm. If you have more than one vehicle you can fit a length of pipe on one exhaust and point it at the tank of the other so you don't have to run both all night.
The best cold start device I used to use is a blow lamp in the air intake pipe to get hot air going in. I wonder if toyota do an electric block heater?
There are some very good extra filters about with a built in heater but that doesn't heat the tank.
The best cold start device I used to use is a blow lamp in the air intake pipe to get hot air going in. I wonder if toyota do an electric block heater?
There are some very good extra filters about with a built in heater but that doesn't heat the tank.
pugwash
Well-Known Member
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- Mar 1, 2010
- Messages
- 484
- Country Flag
you can get in tank heaters, as well as block heaters, sump heaters and gerbox heaters if you are going somewhere very cold- they don't take much power, but massively help the engine out.
The chaps who drove their Yota to north Alaska in The overland Journal used them.
Can pull out the link if anyoner is really interested.
The chaps who drove their Yota to north Alaska in The overland Journal used them.
Can pull out the link if anyoner is really interested.
