air in fuel

based on what i've read in a number of posts by some of the oracles on here, i cut my sedimentor out the other day. seems to have made a difference, which is great, but only when run in for a couple mins. luckily only pipe i found to patch it up was clear n on start up i noticed bubbles comin from tank outlet, followed by a rythmic squirtin noise (in time with pump delivery) 1-2 mins later, then solid fuel after another 1-2 mins. cant see it bein loss of vaccuum due to cuttin pipe, but im probably wrong?

so my other thought was sender pipes on top of tank? am i in the right direction? any pointer/advice be great!

i would be looking there ,good thing bypassing sedimentor,the pipes are fairly good till under bulkhead

i plan to bypass the sedimenter today, ive got 2 meters of 8mm fuel pipe and hose clips. i plan to go from the tank outlet, but not exactly sure where in front of the sedimenter to cut. any thoughts please
Gary

OP,the pipes on the top of the tank and the unions there are a trap for all sorts of wet crap that leads to pinhole rot that isnt that obvious to the eye. Take up the access panel in the loadspace and give the area a good scrub clean,blow the thing over with an airline if you have one.How sure are you of your lift pump ? I cant see how it would be pulling air instead of fuel from the tank but its worth a look in case air is getting in and working back while the engine is off.

Theres a trick you can do when joining rubber/plastic hose to metal,which is to try and get a plumbing compression fitting olive of the correct size and fix that on the metal about a quarter inch from the end.Araldite will do if you cant solder there.Then heat the rubber pipe end in hot water and slide it onto the metal and over and past the olive for an inch or so.Then use your jubilee clip in the middle of that inch. Its called a Corbin Joint,after the brother of the politician of that name who popularised it.May not be able to do it in this case,but its worth knowing and bearing in mind as it makes a very fuel and air tight union.

Gary,that all depends on how confident you are in the state of the piping already there. If you are planning to go right from the tank head it may be worth getting a new part as then you will know that its good and not have to go back and do it again. Otherwise find a place for the join that can be accessed but isnt a crap-trap and has good condition pipe.As I say,all depends.

job done took all of ten minutes and i think a positive result, no air when i bled system.
thankyou shocker, i found an area to cut just before the first clip after the sedimeter.

jamesmartin said:

i would be looking there ,good thing bypassing sedimentor,the pipes are fairly good till under bulkhead

Click to expand...

thought you may say that james, urs was the most common advise i followed. does make sense as the metal pipes were bolloxd

shocker said:

OP,the pipes on the top of the tank and the unions there are a trap for all sorts of wet crap that leads to pinhole rot that isnt that obvious to the eye. Take up the access panel in the loadspace and give the area a good scrub clean,blow the thing over with an airline if you have one.How sure are you of your lift pump ? I cant see how it would be pulling air instead of fuel from the tank but its worth a look in case air is getting in and working back while the engine is off.

Click to expand...

are they easy replacable or is it worth a new unit? lift pump is a newish 1 borrowed from a mate, did sort a few issues but spose it could be on its way out too...

worth fitting uncoroded one if you can one which may mean new ,i usually do both and lift pump so you know systems good

Its normally not the unit itself on top of the tank but the unions and pipes adjacent,but thats not set in stone,you will have to clean it up and decide.Fiddly to do the pipes but no more so than any others.The tank entry unit is easy enough to do but hopefully you wont need to.Let us know how it goes

shocker said:

Its normally not the unit itself on top of the tank but the unions and pipes adjacent,but thats not set in stone,you will have to clean it up and decide.Fiddly to do the pipes but no more so than any others.The tank entry unit is easy enough to do but hopefully you wont need to.Let us know how it goes

Click to expand...

not to sound stupid, but your advisin to get rid of union joints and make new? which explains instructions to do with olive and clips? (just had 2nd baby so heads still with fairies , hence takin a while to process info :doh

Eh ? Im advising what ? two different things,tank and sedimentor,two different jobs...in fact three..that I gave advice on,viz;

1 - possible methods of locally bypassing sedimentor,including use of olives and clips to make better seal on join between metal pipe and hose,if that is the chosen approach

2 - looking for air ingress due to degradation around tank top pipe entries

3 - replacing tank entry unit and/or complete new pipe from there to front of vehicle

I merely suggested common problems and possible approachs to them,as I said,and you quoted me,these things are not set in stone.....clear now ?

shocker said:

Eh ? Im advising what ? two different things,tank and sedimentor,two different jobs...in fact three..that I gave advice on,viz;

1 - possible methods of locally bypassing sedimentor,including use of olives and clips to make better seal on join between metal pipe and hose,if that is the chosen approach

2 - looking for air ingress due to degradation around tank top pipe entries

3 - replacing tank entry unit and/or complete new pipe from there to front of vehicle

I merely suggested common problems and possible approachs to them,as I said,and you quoted me,these things are not set in stone.....clear now ?

Click to expand...

yeah i get that, missunderstood what you were sayin i think :doh:. sedimentor - done, fine. air defo comin in before the new pipe section. i though you were sugestin replacin tank unions to try and erradicate the issue, as i dont understand how just cleanin top of sender could stop air ingress? . is there gonna be any signs of air after its clean?
i value your input & help, you clearly know what your talkin about, we've all got to start somewhere and or me this is the startin point

there 2 places at rear where air gets in seimentor and pipes coming from sender unit those pipes rust and only cure is new or good second hand one,whether you use hose clips and rubber pipe or plastic and nut and olive makes no difference ,passenger side pipe is suction one

jamesmartin said:

there 2 places at rear where air gets in seimentor and pipes coming from sender unit those pipes rust and only cure is new or good second hand one,whether you use hose clips and rubber pipe or plastic and nut and olive makes no difference ,passenger side pipe is suction one

Click to expand...

yeah, thats what i were thinkin. cleaned the pipes up and they still look pretty shiny under all the ****e. bluntly - how do i tell if it is leakin? if theres even a cut n dry way to determine? i get the feelin its gona be one of them 'change everythin till it works' jobs.

Mate,you are right,its a process of elimination. You do the cleaning to see if there is any obvious damage to the pipes,often if they are leaking air in its due to degradation of the surface and consequently obvious.All you can really do is the old sherlock holmes - when all the other possibilities have been eliminated,whatever is left must be the truth.

....and you picked a pretty tricky area to start on !

shocker said:

Mate,you are right,its a process of elimination. You do the cleaning to see if there is any obvious damage to the pipes,often if they are leaking air in its due to degradation of the surface and consequently obvious.All you can really do is the old sherlock holmes - when all the other possibilities have been eliminated,whatever is left must be the truth.

....and you picked a pretty tricky area to start on !

Click to expand...

glad im not jus bein completely 'tarded then ha. like i said, the pipes have all scrubbed up pretty well, id go as far as to say the unit looks almost new. within the last few years anyway. having no receipts from prev owner for any work its hard to tell (service stamps up till 2008 tho). think im gona start with new lift pump as its cheapest to replace . was thinkin of removin union nuts off sender and sleavin fuel pipes straight over metal pipes (which is what i were tryin to say other night, but my head werent all there) worth a try, as if the unit is knackered, its gota come out anyway, so cuttin pipes wont matter and if it works, great

That,if you could get a secure fit (maybe heat the plastic pipes in water first?) ,would certainly take faulty unions out of the equation....but dont go chopping things up until you have eliminated everything else,mate......diesel work is like working on an old clock - one thing at a time and thoroughly done.Dont get distracted and start jumping from one place to another,be methodical.Its all very logical really,just bloody frustrating !