Biopowered - vegetable oil and biodiesel forum
General => Chatter => Topic started by: Head Womble on May 05, 2016, 08:32:35 PM
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Help guys, the disco is going through fuel filters again.
I was using cheap crap, but swapped over to MANN filters last year, over winter I was running dino (don't ask), as soon as I filled up with bio the filter blocked, this was swapped for another MANN filter that has lasted just 700 miles.
Now what has me stumped is when I took it off it was not full of fuel, as the disco has a lift pump before the filter how is air getting into the filter causing running issues yet when a new one is fitted all is ok.
the lift pump is working (pumps fuel from the outlet when cranking), but air is still getting in.
I'm thinking the ally casting of the filter housing may be porous allowimg air in when the filter starts to block.
Any other ideas ?
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I've run on Britpart £2.50 filters for years and never had a problem.
Air could be getting in before the lift pump ... have you check the sedimenter ... conveniently located on the inside of the chassis rail above the rear axle?
Can't remember the exact problem, but I lent my neighbour a length of griflex hose to bypass his sedimenter and said I'd like it back once he'd cleaned the sedimenter out. It cured the problem and guess what, I've never seen the hose again.
Fuel pipes on the tank outlet corrode sometimes and I've seen rusty pickup pipes in the tank.
Got a fuel filter body and a fuel pickup / sender unit (just needs the fuel gauge wire re-soldering) and a sedimenter if you need them.
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If it was getting in before the lift pump changing the filter would make no difference, this one of the things that puzzling me.
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Aren't you talking about two different problems here?
1) Filter blocking
2) Air entrainment
I don't think the two have the same cause.
There's a bleed screw on top of the filter. Have you tried cracking that while it's running?
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Aren't you talking about two different problems here?
1) Filter blocking
2) Air entrainment
I don't think the two have the same cause.
There's a bleed screw on top of the filter. Have you tried cracking that while it's running?
No, I haven't messed with the bleed screw, even when changing the filter I don't prefill it, just start the engine and give it some throttle until the revs rise and off I go.
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It's a LawnRoamer what else do you expect?
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I expect to be able to cut the lawn with it.
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Aren't you talking about two different problems here?
1) Filter blocking
2) Air entrainment
I don't think the two have the same cause.
There's a bleed screw on top of the filter. Have you tried cracking that while it's running?
No, I haven't messed with the bleed screw, even when changing the filter I don't prefill it, just start the engine and give it some throttle until the revs rise and off I go.
Yes, I do the same thing but I do bleed air off the top of the filter once it's running. If you do that and then check it a little later, it will be a good indication of air entrainment.
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I'll give that a go at the weekend.
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if there's a small air leak it might be ok wih a new filter in.... then once the filter starts to block (even slightly) there's a bit more restriction so it either sucks in more air, or the air that's in there makes more of a difference ?
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There's also a strainer in the lift pump. Not all of them are removable depending on what brand you have fitted...
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I wouldn't discount a failing lift pump. I've been caught out like that more than once.
It'll look like it's working perfectly, but as soon as the pressure comes on, either wanting more fuel, or a slightly blocked filter, and it just hasn't quite got it.
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if there's a small air leak it might be ok wih a new filter in.... then once the filter starts to block (even slightly) there's a bit more restriction so it either sucks in more air, or the air that's in there makes more of a difference ?
This is my thoughts,
When a new filter is fitted is back to full power, it then drops off slowly until that critical point when it tails off very quickly.
It's not my fuel as the wife's car doesn't suffer at all.
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There's also a strainer in the lift pump. Not all of them are removable depending on what brand you have fitted...
It has a Delphe lift pump, the one with the filter and I checked it a few weeks ago, all was clean.
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I wouldn't discount a failing lift pump. I've been caught out like that more than once.
It'll look like it's working perfectly, but as soon as the pressure comes on, either wanting more fuel, or a slightly blocked filter, and it just hasn't quite got it.
I replaced the lift pump a while back, it was doing this before and since.
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Today I checked the filter and yes there was air in it, so I removed all the copper washers and annealed them.
Got 5 miles and it was chugging again.
I've now run a clear pipe from lift pump to IP (bypassing the filter) and there's air in the pipe.
So it's either the lift pump, sedimenter or the pipes on the top of the sender.
I'll investigate more tomorrow.
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Today I got time to have a look, I've run a new fuel pipe from tank to lift pump (bypassing the sedimenter) and still had air, so I ran a .3
temp supply to the lift pump, nice clean fuel going in and milky stuff coming out.
A new lift pump is on order.
The old one is a Delfi and has only done about 8 to 10k.
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Glad you sorted it ... and a relatively cheap fix.
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Not sorted yet, still got to fit the lift pump when it arrives.
But £22.50 for the replacement was quite good I thought.
On the down side I noticed my rear diff is leaking oil, well you can't fix one problem on a LR with finding another.
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Not sorted yet, still got to fit the lift pump when it arrives.
But £22.50 for the replacement was quite good I thought.
On the down side I noticed my rear diff is leaking oil, well you can't fix one problem on a LR with finding another.
There's an easy fix for that ... leave it 'till all the oil's drained out ... then it doesn't leak.
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Not sorted yet, still got to fit the lift pump when it arrives.
But £22.50 for the replacement was quite good I thought.
On the down side I noticed my rear diff is leaking oil, well you can't fix one problem on a LR with finding another.
There's an easy fix for that ... leave it 'till all the oil's drained out ... then it doesn't leak.
Well they do say that if an LR doesn't leak then there's no oil in it.
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New lift pump fitted and clear lines run from lift pump to filter, filter to IP.
All looked good, but on a short drive it conked out again, air in the lines, so the only thing left now (I hope) is to replace the sender unit.
After it conked out I bypassed the filter again, and it's got much more power (for a 300dti) so the lift pump was definitely fecked.
Off to evilbay for a sender unit.
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For the second time ... I've got one sitting in the garage!
Let me know if you want it and I'll repair the little wire on the rheostat.
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For the second time ... I've got one sitting in the garage!
Let me know if you want it and I'll repair the little wire on the rheostat.
Bugger, I really should have re-read this thread...
I'm £60 lighter and a new one has been ordered.
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Ah, shame ... I'd have only charged you £55.00.
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Ah, shame ... I'd have only charged you £55.00.
£55 and I'd of had to fix the broken wire, bargain.
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You're right ... you really should read posts more carefully ... I offered to repair the wire before you collected!
It's the least I could do for fifty five quid!
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Well today the new sender unit arrived (quite quick considering it was sent by DPD).
It was fitted as soon as I got home, and guess what, yep, still got air coming from the filter.
So a quick recap, it has a new lift pump, new fuel line from tank to lift pump, clear lines in engine bay.
The only thing left now is the fuel filter housing.
Grovelling time.
Julian, you know how I always read your posts and digest every word at least three times, and imprint them in my teeny tiny mind, well........................urm...............you said something about a filter housing....................
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Hang on ... let me read back through my posts to see what I said.
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Youve done a fair bit of work -
When i re-plumbed the 101, i used clear throughout, and compression fittings with inserts.
When i started it, some were leaking, but i just tightened them up bit by bit on tickover until no air.
SSL will sell you all manor of banjo sizes and inserts for clear nylon tube (i got my tube from a hydraulics place) - if i ever have that kind of issue on another tdi, it will be one of the first things ill try, as it lets you see exactly where the air is getting in.
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ps.
ive changed the lift pump on an, otherwise, known good setup before, and had an issue getting the olives to seal
thinking about it....
if you have a leak post lift pump, then it will be diesel comming out, rather than air going in, surely?
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OK, it's here waiting for you.
Only condition is that I have the old one in exchange ... it's part of a long term (very long term) heated filter project.
It's been a while since I stuck my head under the bonnet but isn't the fuel filter on the pressure side of the lift pump? If you get air from the bleed screw, there must be pressure in there to push the air out.
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thinking about it....
if you have a leak post lift pump, then it will be diesel comming out, rather than air going in, surely?
That is exactly how I saw it and it's bugging me as to why it's doing what it is.
Only if the filter was very badly blocked should you get air being sucked in at / or after the filter.
Maybe I should put on yet another filter and see how I go now the rest of the system is sealed.
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OK, it's here waiting for you.
Only condition is that I have the old one in exchange ... it's part of a long term (very long term) heated filter project.
It's been a while since I stuck my head under the bonnet but isn't the fuel filter on the pressure side of the lift pump? If you get air from the bleed screw, there must be pressure in there to push the air out.
Yes air is pushed out from the bleed screw (after the lift pump) and mine is still doing this, I'll try a new filter before robbing you of a housing.
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My money is on the olive on the suction side of the lift pump.
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A new filter and tightening up all the olives done the trick (for now).
It's now running 50/50 veg/dino (soon to be 100%), time to fit the LPHE that Julian gave me some time ago.
Thanks for you help guys.
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What's a LPHE ?.
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It's, a, um, a, er, flat plate heat exchanger