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Big Green View Drop Down
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    Posted: 25 Sep 08 at 18:48

Hello everyone, love the site. first post in this section. have already posted in the tech section.i dont know anything about engines,but i think i have air in the fuel line.van wont start but if i try to turn it over there seems to be air bubbles in what i would think is the return if that makes any sense at all.when i say return i mean that i can see fuel going from filter to pump then down lower theres another clear plastic pipe with what i think is fuel with air bubbles in it. if that makes sense to anyone is there some way to get the air out.thanking you in advance.

1993 vw lt35 2.4d
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thal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote thal Quote  Post ReplyReply Direct Link To This Post Posted: 25 Sep 08 at 20:56
it may just be an airlock after running low on fuel. Start by loosening the feed pipes at the injectors 1/2 turn while turning the engine over till you get fuel coming out retighten the nuts, then undo the banjo bolt on the return pipe where it connects to the pump 1/2 turn wait for fuel, retighten. if you still have air bubbles the air must be coming from somewhere else in the system, first of all nip up any joints in the pipe ie where it joins filter ect if this doesnt stop it then there may be a leak in the pipe itself and you will have to trace it from the fuel tank forwards, look for oily patches on the pipes as an indicator. Replace any that look dodgy.
TERRY
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MostlyMonki Quote  Post ReplyReply Direct Link To This Post Posted: 26 Sep 08 at 15:10

i had the same problem. take the fuel line off the diesel filter and run it to a jerry can with diesel in (so you've got a line from that can directly to the fuel pump) - see if it starts ok. if so then swap round the 2 pipes on the fuel tank for a quick fix if you need it running pronto.

"LT Massive"
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thal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote thal Quote  Post ReplyReply Direct Link To This Post Posted: 26 Sep 08 at 20:56
swapping the lines will certainly get you running quick and once started itll be easier to find where the bubbles are comming from
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Big Green View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Big Green Quote  Post ReplyReply Direct Link To This Post Posted: 27 Sep 08 at 18:01
thanks for replys.have van running again.followed thal advice and it worked a treat.i am thinking of fitting a non return valve on fuel line as i am getting fuel flowing back into tank if van is idle for any lenght of time.
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thal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote thal Quote  Post ReplyReply Direct Link To This Post Posted: 27 Sep 08 at 18:10
a smple nonreturn valve cost me afiver fit it between filter and pump for best results
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Post Options Post Options   Thanks (0) Thanks(0)   Quote madra Quote  Post ReplyReply Direct Link To This Post Posted: 11 Feb 09 at 16:03
i've got the same problem myself.  if i leave the van standing for a day or two, it's a bugger to start and i can see air bubbles in the transparent section of pipe leading from the fuel filter to the injector pump.

although it looks a nailed-on air leak in a fuel pipe somewhere, the weird thing is that - once i've sooked the air out of the system, the engine seems to start and run fine and the remaining bubbles clear after about five mins or so.  i have an old isuzu trooper which has suffered similar air in the fuel problems in the past and, on that, it's always been really obvious that one of the pipes is sucking in air, because the engine will start but then will refuse to accelerate above idling speed: if i press the accelerator, the revs momentarily pick up but then just drop down to idle again.  since those are the symptoms i'm used to when there's air being sucked into the system on my trooper, i'm a bit puzzled by the different behaviour of my van. 

the fact that the bubbles clear after a few minutes and the engine revs OK once started makes it seem like there's no air being sucked in while the engine is running, but that somehow air is getting into the system when the van is left standing for a couple of days.  it's almost like diesel is draining back out of the injector pump, coz when i bled it today, i watched quite a bit of diesel being pumped up the transparent tube from the filter into the injector pump before any came out at the loosened injector nozzles.

do you reckon one of those non-return valves would help? - or have i got a leak somewhere that's so small it's going to be needle-in-haystack time, trying to find it?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bushbandit Quote  Post ReplyReply Direct Link To This Post Posted: 11 Feb 09 at 17:36

I had the same problem too.  but when i went to start the van it would take 30sec or more of cranking to get it to fire,  you could then watch the airbubbles flow up to the diesel pump.  Then it would run fine.  When you turned the engine off you would then see all the fuel flow back out again.  I put in a non return vulve in that i got off ebay.  Then found out the diesel pump was wet and dripping round where the belt was, turns out the sharft was worn and letting in air from the so breaking the vacume the pump was making. 

But that could be just one cause.
 
T
1985 LT31 LWB 2.4D, Diamond RV custom conversion, with all the whistles and bangs!!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote madra Quote  Post ReplyReply Direct Link To This Post Posted: 11 Feb 09 at 18:24
Originally posted by bushbandit bushbandit wrote:

...found out the diesel pump was wet and dripping round where the belt was, turns out the sharft was worn and letting in air...


ouch! that must have been a pisser.  fingers crossed mine's just a leaking pipe then.  if the pump's knackered i'll be getting rid of the van - a new diesel pump would set me back more than i paid for the van in the first place.

speaking of possible air-leaks - there's some kind of weird plastic plug on the top of my fuel filter that the return pipe [?] passes through.  the plug seems quite loose in that i can twist it round quite easily. i've never seen a plug like this on any other diesel fuel filter i've come across.  anyone know what it might be? - coz if there's air getting into the system anywhere and this plug thing is supposed to be airtight, then it'd be my number one suspect for leaking like a seive.

sorry - that was a bit of a crap description, but it's too dark to get a photo now, so that'll have to do til i can snap it tomorrow.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote madra Quote  Post ReplyReply Direct Link To This Post Posted: 11 Feb 09 at 19:20
[FOLLOW-UP]

silly me.  forgot i had a flash on the camera:

anyway, here's the mysterious plug on the top of my fuel filter and - as i said above - prime candidate for the 'letting air in' prize in my book, as it's possible to twist it round by hand, so if it's meant to be airtight it probably isnae.

anyone know what it is?  the pin on the top looks like sommit off a hand grenade!


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thal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote thal Quote  Post ReplyReply Direct Link To This Post Posted: 11 Feb 09 at 19:25
check the cnections on all your pipes are tight including the copper washers on the banjo conections.also check the return pipes are in good condition Fit a none return valve £5 from most car shops between the filter and the pump it usualy works
Terry
2.4 td high top home conversion And2.4td LWB high top van
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mike38 Quote  Post ReplyReply Direct Link To This Post Posted: 11 Feb 09 at 20:02
I took that type of filter off and put one on the same as the one under the wheel arch it looks the same has 2 pipes but the bit with the clips not there i then joined the two pipes together that used to go to the plug .Someone on here recomended it when a speacilist tuned there van think its an escourt filter ?.

Mike
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Post Options Post Options   Thanks (0) Thanks(0)   Quote madra Quote  Post ReplyReply Direct Link To This Post Posted: 11 Feb 09 at 20:07
so does that plug thing actually go into the filter, or is it just clipped onto the top?

if it's just clipped onto the top, i was actually thinking of just joining the two pipes together and bypassing it - one less potential source of an air leak to worry about
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mike38 Quote  Post ReplyReply Direct Link To This Post Posted: 11 Feb 09 at 20:35
its some kind of valve think it allows fuel back into the filter mine cracked when i was changing the filter so i binned it and by passed it but yes you will need a filter without it then or you will have a big hole in the top of the filter lol.

Mike
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PRODIGY69 Quote  Post ReplyReply Direct Link To This Post Posted: 17 Aug 11 at 11:58
can anyone tell me wht size return valve i need please for me lt 1993 thanks diesel non turbo
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Toggs Quote  Post ReplyReply Direct Link To This Post Posted: 18 Apr 18 at 22:34
Hope You got it Sorted?
I know its a few years since these symptoms were raised and I am curious to what the outcomes are. I am new to this site and I am hoping someone could suggest or know what I need to next? I have an LT35 2.4D (1992) which I have had for 18yrs which I converted into a Camper. I love it! Recently I noticed air bubbles in the Feed Pipe between the Engine Bay Fuel Filter and the Pump. I checked all Hoses and connections all the way back to Wheel arch Filter (All ok). I then exchanged both Filters and filled with Diesel. Ran great until Fuel ran out of Filters. I checked the Fuel Line which connects the input of the Wheel Arch Filter which when I primed with a hand held Primer Pump into a Container it was drawing Air in from somewhere between Tank and Filter. How easy is it to drop the Tank to check connections? Could I swap the fuel lines around on the Tank to test output Hose to see if it still draws air or air these strictly for supply and return?
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