I have an issue that maybe someone out there in motorhome land can give me some advice.
As you can see...I drive a big bus and the fuel tank contains apporox 350 litres.
My useage is about 2.5 to 2.8 klms per litre....So I should be able to travel well over 600+ Ks.
However on recent trips I only get to about 300 ks and I 'run out' but the tank is still half full (or half empty)
Fortunately I have been stationary when I have stalled and discovered that 'Ive run out'.
When refueling I've only tanked just over the 100 lts.
My suspicions are that the pick up pipe is sitting at the half way mark and I cannot access the bottom of the tank.
You might say "locate the pick-up tube on top of the tank and pull it out to see where it sits".... but the fuel tank is somewhat burried and is difficult to get to.
And ....What am I likely to find on the bottom of the pick-up tube....I have never seen what's down there.
Well these type problems can be hard to fathom sometimes.
It is unlikely IMHO that the fuel pick up pipe is broken say 1/2 way along its length.
If you can undo the fuel line a blow back into the tank with your mouth only or very limited compressed air say 10-15 psi (with the filler cap OFF as you don't want to distort the tank) it may be that the pick up tube has filter on the end and becomes clogged. By blowing you may clear it and ask someone to listen for bubbles at the same time. Strange as it may seem bubbles near the surface of the fuel (if pick up is broken) will/may sound different to bubbles with a "deeper" sound coming from the bottom.
Drain any water from the tank also to check for other solids etc that may be there.
If you can blow back into the tank at least the fuel line has been "back-flushed a bit.
Other wise drain the tank and use torch to see inside or wire inside to get an idea if the pick up is close to the bottom. How do you do this,,,, wire about the diameter of a coat hangers is good, bend it as you work it in so that it follows the bottom of the tank toward the pick up (use a mirror to find it on the outside of the tank) and move wire around to see if you can find it. Can be very difficult and frustrating but may just help.
__________________
Why is it so? Professor Julius Sumner Miller, a profound influence on my life, who explained science to us on TV in the 60's.
Well these type problems can be hard to fathom sometimes.
It is unlikely IMHO that the fuel pick up pipe is broken say 1/2 way along its length.
If you can undo the fuel line a blow back into the tank with your mouth only or very limited compressed air say 10-15 psi (with the filler cap OFF as you don't want to distort the tank) it may be that the pick up tube has filter on the end and becomes clogged. By blowing you may clear it and ask someone to listen for bubbles at the same time. Strange as it may seem bubbles near the surface of the fuel (if pick up is broken) will/may sound different to bubbles with a "deeper" sound coming from the bottom.
Drain any water from the tank also to check for other solids etc that may be there.
If you can blow back into the tank at least the fuel line has been "back-flushed a bit.
Other wise drain the tank and use torch to see inside or wire inside to get an idea if the pick up is close to the bottom. How do you do this,,,, wire about the diameter of a coat hangers is good, bend it as you work it in so that it follows the bottom of the tank toward the pick up (use a mirror to find it on the outside of the tank) and move wire around to see if you can find it. Can be very difficult and frustrating but may just help.
Gee Baz to do that on my bus I would have to become a contortionist but I do understand what you are saying..
I do have an access panel in the floor that is currently covered by cupboards but with a little effort I can get to it and then remove the fuel gauge float and get a good look into the tank.. Like Baz said maybe blowing the fuel line back could clear some rubbish in the line, there is a very small chance you have a virus in your tank and it is blocking the pick up line.
maybe syphon out the fuel in the tank and have a close look at it, it may contain some solids that are causing some the problem. If I was doing the job I would syphon into an open container and tip the clean fuel into sealable containers untill you have the tank empty, you may be surprised what comes out of the tank..
Other than that I cant think of any other reason except for a broken pick up tube.. Which I hope it isn't..
Well these type problems can be hard to fathom sometimes.
It is unlikely IMHO that the fuel pick up pipe is broken say 1/2 way along its length.
If you can undo the fuel line a blow back into the tank with your mouth only or very limited compressed air say 10-15 psi (with the filler cap OFF as you don't want to distort the tank) it may be that the pick up tube has filter on the end and becomes clogged. By blowing you may clear it and ask someone to listen for bubbles at the same time. Strange as it may seem bubbles near the surface of the fuel (if pick up is broken) will/may sound different to bubbles with a "deeper" sound coming from the bottom.
Drain any water from the tank also to check for other solids etc that may be there.
If you can blow back into the tank at least the fuel line has been "back-flushed a bit.
Other wise drain the tank and use torch to see inside or wire inside to get an idea if the pick up is close to the bottom. How do you do this,,,, wire about the diameter of a coat hangers is good, bend it as you work it in so that it follows the bottom of the tank toward the pick up (use a mirror to find it on the outside of the tank) and move wire around to see if you can find it. Can be very difficult and frustrating but may just help.
Gee Baz to do that on my bus I would have to become a contortionist but I do understand what you are saying..
I do have an access panel in the floor that is currently covered by cupboards but with a little effort I can get to it and then remove the fuel gauge float and get a good look into the tank.. Like Baz said maybe blowing the fuel line back could clear some rubbish in the line, there is a very small chance you have a virus in your tank and it is blocking the pick up line.
maybe syphon out the fuel in the tank and have a close look at it, it may contain some solids that are causing some the problem. If I was doing the job I would syphon into an open container and tip the clean fuel into sealable containers untill you have the tank empty, you may be surprised what comes out of the tank..
Other than that I cant think of any other reason except for a broken pick up tube.. Which I hope it isn't..
Yep Bob us old timers had to "fix" things and not replace em eh. Have physically done this but can be a pain in the u know what I agree,,, but if it's the only access!!!!!!
__________________
Why is it so? Professor Julius Sumner Miller, a profound influence on my life, who explained science to us on TV in the 60's.
I have had that problem with a coach before and it was the pick up pipe, its a very big job if that is it as you will have to pull the whole tank out and that will take two people .
Something else that you may wish to check is the fuel line fitting to the tank pickup unit.
I have come across this before where the connection s not fully tight, works OK while fuel level is high, as the fuel level drops the lift becomes higher,if there is a minor air leak then it becomes easier for the lift pump to suck air rather than fuel.
Same could apply to any joiner within the length of the line. Like said,I have seen this happen.
JC.
__________________
Be your self; there's no body better qualified ! "I came into this world with nothing , I still have most of it"
Had a similar issue with one of my trucks. The fuel pickup pipe was made of steel and had a rust hole part way along. All was fine when the tank was full but when it got down a bit it sucked air.
I have an issue that maybe someone out there in motorhome land can give me some advice.
As you can see...I drive a big bus and the fuel tank contains apporox 350 litres.
My useage is about 2.5 to 2.8 klms per litre....So I should be able to travel well over 600+ Ks.
However on recent trips I only get to about 300 ks and I 'run out' but the tank is still half full (or half empty)
Fortunately I have been stationary when I have stalled and discovered that 'Ive run out'.
When refueling I've only tanked just over the 100 lts.
My suspicions are that the pick up pipe is sitting at the half way mark and I cannot access the bottom of the tank.
You might say "locate the pick-up tube on top of the tank and pull it out to see where it sits".... but the fuel tank is somewhat burried and is difficult to get to.
And ....What am I likely to find on the bottom of the pick-up tube....I have never seen what's down there.
Any help from you Teckies....muchly appreciated.
Cheers
Frank
Depending on the bus and model, along with the engine you have in it, it may be a simple problem to fix. if it has another engine and not the original, the fuel system may not be quite right for the engine, so over time may create problems. Our Bedford had a 500 diesel in it, we put in a bigger capacity turbo Isuzu and 12mm fuel lines to compensate for the fuel draw. We also changed the return line and looped it back into the fuel intake, removing more pressure on the fuel lines. A bit of over engineering, but it works nicely for us.
Many English buses had a small mesh filter on the end of the pickup which can become blocked restricting fuel pickup when levels get low, as the weight of fuel on the pickup drops. You should be able to unscrew the pickup out of the top of the tank and lift it out, then you can see if there is a problem. If there is a mesh filter on the end, take it off and install an in line throw away filter between the tank and engine at a low point of the fuel system. Then if you need to change it, you refill the new filter by gravity and not have to bleed. It also lengthens the life of your main filter and gives you an easily inspected filter, we used them all the time on big long runs into the bush, no matter what you do, dust or something always gets into the fuel system, over time.
Or it may be what we used to call ghost blockages, they come and go, but you can never seem to find them, until you drain the tank. For some reason baffled tanks which may have some junk in them, seem to push the junk well away from the pick up, but as fuel gets low the junk is drawn the to pickup and blocks it. When you put fuel in the junk is pushed under the baffles and away from the pickup. All you can do is drain the tank and see what comes out, in fact you should drain your fuel tank regularly because of buildup when being fueled, as moisture and junk does get in and diesel does create a build up in the tank. This bus we have now, we drained and flushed the tank with BD and there was a lot of junk in it. The quality of fuels is some times not up to standard, so if you have a clean fuel system, you've got a better chance of avoiding problems.
Then again it may be your fuel pump, having trouble drawing fuel, to overcome that, we use in line facet pumps, which assist, or take over from the main pump if something goes wrong. Understand most wouldn't bother doing what we do, but it keeps us on the road and when you are a long way from the local garage or service people, you're mostly on your own.
I recall a couple of years back a truck I was driving at the time developed a unknowing fuel problem. At first the truck at about half full with fuel would what seemed loose power when loaded going up a rise. That night I said to the boss the truck is loosing power, being a regular penny pincher did nothing until one day down the track it played up low on fuel it would of not idle and totally down on power.
Into the dealer for a look see why the engine would not idle as we needed that for pump work being a fuel delivery in their invesigaton they found a small gum nut lodged up the pick up pipe.
The desiel truck I was driving was in it's second year of operation with me as the only driver and fueling regular at our own fuel company terminal.
Also had a experience a long time back where the pick up pipe entered the tank it had a crack causing the engine to suck air and finally stop until fault was found.
Good luck to find pesky fuel fault, remember you can keep the tank full and wait for the fault to get even worse. Cheers
Last line was tongue in cheek but that would be no fun.
-- Edited by Radar on Thursday 27th of March 2014 10:01:21 AM
All you guys are just great ....terrific responses.
I have since cut away the side panel of the bus that covers the fuel tank,
this allows me acess to the top of the tank. Then I disconected the flange where the suction & return line feed to the tank.
This then allowed me to withdraw the suction standpipe. It does have a gauze strainer on the bottom that appers fine.
I will shortly (once it stops raining) get under there to see how I am going to drain the tank.
I am still not able to look inside the tank as my head wont fit in that space above the tank.
One other question....
Someone offline mentioned that the return line should go into the tank at almost the same depth as the pick up...but there is no tube from the return going into the tank...it just terminates at the top where the flange/elbow is at the top of tank.
Should there be a tube down from that into the tank from the return line??
I'v had a lot of fuel pickup assy tubes out of tanks & don't ever recall seeing a second tube returing to the bottom of the tank. Not saying that it has never been done just dont see any reason for it, as long as the excess fuel is returned to the top of tank that should be ok.
The excess fuel works as a cooler for the fuel system.
Q, does this unit have a inline fuel filter with a replaceable spinon cartridge & a primer pump on top?
I have also seen slithers of plastic water hose from siphoning fuel lodged in the non return valve on the tank side of this filter housing, caues the lift pump to stop pumping.
The old saying in the trade, when its not the obvious look for the rediculise.LOL
__________________
Be your self; there's no body better qualified ! "I came into this world with nothing , I still have most of it"
All you guys are just great ....terrific responses.
I have since cut away the side panel of the bus that covers the fuel tank,
this allows me acess to the top of the tank. Then I disconected the flange where the suction & return line feed to the tank.
This then allowed me to withdraw the suction standpipe. It does have a gauze strainer on the bottom that appers fine.
I will shortly (once it stops raining) get under there to see how I am going to drain the tank.
I am still not able to look inside the tank as my head wont fit in that space above the tank.
One other question....
Someone offline mentioned that the return line should go into the tank at almost the same depth as the pick up...but there is no tube from the return going into the tank...it just terminates at the top where the flange/elbow is at the top of tank.
Should there be a tube down from that into the tank from the return line??
Cheers again and thanks for your help.
Frank
The return line is so a lot of fuel flows through the system aiding in lubrication and cooling of the fuel system, if it ends in a "t" joint near the tank, that's fine as it is being put back into the system. It's a common thing and you shouldn't put the return line deep into the tank, as it will create a resistant pressure buildup in the return line and could cause starving of the engine. You could also disconnect the return line at the tank end to see if it has a non return valve in it and if it is flowing freely.
1 blow through the pick up line IN REVERSE direction even if filter looks good.
2 Were the fuel line return fittings tight, it not allow air to be drawn into the pickup line IF THEY HAD A COMMON FITTING
3 Maybe look into the tank with a mirror???? But maybe no usefull especially if fuel pick up line/filter is not blocked.
4 Justcruisin has a good point check blocked filters etc,,, again try to blow back through fuel line from filter inlet to tank pickup
5 Blow back through filter
6 Blow back through fuel line from Injector pump inlet to fuel filter outlet (wherever the fuel pump is disconnect fuel lines each side and blow back)
7 If you still can't find a fault maybe drain the tank,,, but if fuel filter and lines OK suggest this is not a tank problem here.
8 You may have to get fuel pump pressure checked.
One from left field,,, did your engine stall ONLY when idling, if so for how long was it idling, and what was the temperature of the day hot/cold. Temperature variations can sometimes allow air to be drawn into "loose" copper fittings.
Keep going mate and good luck.
__________________
Why is it so? Professor Julius Sumner Miller, a profound influence on my life, who explained science to us on TV in the 60's.
