300TDI faulty fuel sender??

Hi.

I'm currently trying to solve a problem with a 97 300TDI discovery.
It cuts out under revs and only revs to about 3000. On releasing throttle it cuts out then.

I have traced the problem to the fuel sender in the fuel tank. I extended the fuel lines from the sender and put them in another diesel tank and it runs fine so would seem to be the sender at fault.

The sender itself looks quite new. I removed it, checked for blockages etc but it seems fine. Does the sender actaully do anything? I was under the impression that it was just two lengths of pipe and the reader for the fuel guage. What I'm asking is there anything, internally, within a fuel sender that can go faulty before i buy a replacement and pay good money after bad!!

Thanks in advance.

Faulty/weak lift pump?? When using the secondary fuel reservoir was this higher than the vehicle`s tank? Maybe a weak lift pump can`t supply enough fuel but with a gravity aided supply it can?

remove it and have a look some have filter at bottom ,some have rubber pipe inside

I don't think it needed it but I replaced the lift pump yesterday and it made no difference. I removed the sender today and ran some brake cleaner through it and it seemed fine????

Have you cleaned the sedimentor? also check fuel lines at connections for any signs that air may be getting in to the system, check 2 elbows on top of sender, if corroded they could be pin holed & let air in. you could also fit clear fuel pipe between lift pump & filter that way you will know if there is any air in system. Try tapping into fuel system with piece of pipe & can of fuel as process of elimination. Been there & done that.

Sedimentor has been by passed in the past. Sender is plastic so no metal elbows visible. I've had it running by putting the fuel lines from the sender into a can of diesel so process of elimination says it's the sender but I can't see what could be wrong with it to be drawing in air!!

Have you checked the fuel cap vent is not blocked ?

Ive fitted the new sender unit but still loads of air from bleed screw. Im thinking must be sedimenter now. Will have to bypass it.

bleed it from front fuel pipe on pump ,it gets rid of all the air

jamesmartin said:

bleed it from front fuel pipe on pump ,it gets rid of all the air

Click to expand...

Ive had the banjo bolt loose on fuel pump and it was ****ing out. How long do you need to let it run ? Fuel filter keeps emptying so when I start engine it takes a minute for any fuel to appear at bleed screw. Still full of tiny bubbles. It must be getting in on sedimenter.

I think you will find that every time your fuel filter empties, air will be entering the system. So you seem to be going round in circles.

Discodave2011 said:

I think you will find that every time your fuel filter empties, air will be entering the system. So you seem to be going round in circles.

Click to expand...

I was going to bypass the sedimenter originaly but couldn't find anywhere that did fuel pipe in more than 1 metre lengths. Im going to bypass it today. Can't think of anywhere else it could be getting in.

After days of messing around I sorted this. It was a faulty, plastic union on the fuel line to the lift pump. When I tested the pump by putting fuel direct to the pump I disconnected it and must have pushed it back on tight when I tested it from the tank. I'm really annoyed that it took so long and in the process I've checked and replaced every joint in the fuel lines but at least I only forked out for a new lift pump and not a new sender unit!!!

I've had the same issue....changed filter and pump still have champagne at the bleeder. Where was this plastic union? Might be my issue. Glad you sorted yours.

Got a similar issue on my 200tdi disco, although mine has had the sedimentor bypassed (before I bought it) so I'm thinking either letting air in there or rotten metal pipes on tank sender thinggy

Spose I'll have to get dirty

Rich.

Zed. said:

Got a similar issue on my 200tdi disco, although mine has had the sedimentor bypassed (before I bought it) so I'm thinking either letting air in there or rotten metal pipes on tank sender thinggy

Spose I'll have to get dirty

Rich.

Click to expand...

Well, got brave & dirty

Lifted the boot carpet & insulation foam mat thinggy (didn't quite like what I saw )
My '91 Disco has had a new tank sender / pickup recently before I bought it, this was a welcome surprise but the pipe unions looked somewhat horrid So bravery or stupidity happened & the spanners came out to play........

Both feed & return were 'finger tight' although there was no Diesel loss from the return

Tightened up & test driven, back up near its 110bhp now

Rich.



Ps. Anyone know what thread the pipe unions are on the sender? Can feel some new ones in the future

try nrc9770 and nrc9771