300tdi Starting Problem

I've got a 300Tdi disco and it stuggles starting. I have to give it plenty of throttle to get it to go. I don't think its the glow plugs as it does it even when the engine's hot. Could it be fuel running back?

I had this - perhaps....

Hard to start but eventually it will - 15 seconds of cranking always did the trick. Belch of whits smoke then ran like a watch for the whole day, next time it was left for a few hours though - hard to start again. It was indeed "runback", I'm not sure if it was the pipe or the sedimenter though as I took no chances :


I got a box of jubilee clips and a length of fuel pipe from halfords, they do it on the roll, replaced the entire "suction" side from tank to fuel pump and just for good measure swapped the pipes at the tank - the return goes almost all the way to the bottom of the tank (about 1/4" shorter than the feed on my tank).

Problem fixed, starts at first turn every time. Cost £30, time 1 hour.

Yes that sounds similar. If i start it with my foot to the floor it will go but not otherwise. My mate suggested a non-return valve?

The valve, jubilee clips and a couple of short bits of fuel hose will not cost far from a whole length and from what I have read, a lot of the time the problems are actually attributable to the sedimenter, which would still let your line fill with air, although this should be slurped through pretty quickly once you start.

As said, a full length hose replacement did the job for me.

I am still having the same problem, it was described better by another member about a year ago - http://www.landyzone.co.uk/lz/f8/weird-starting-issue-31053.html?highlight=solonoid

Does anyone know any more about this? I can't find any more threads about it.

Tom.

Sounds like a different problem to me, the one I described is sometimes called "runback" and is to do with fuel from the suction line dribbling back into the tank so the line fills with air, when you start cranking you cannot pressurise the lift pump and air spills into the injector pump, crank for long enough and it will start but not without the big white cloud I mentioned.

This is often caused by porosity in the lines, sedimenter, connections, leaky joints and duff pump diaphragms. The only one I'm sure was not contributing to my problem was the fuel pump and diaphragm as replacing that made no difference. Running a completely new fuel line from tank to lift pump replaced all the rest in one go, so I've no idea which was at fault.

As of right now, it still starts the instant it is cranked. Fixed.

nucleus, your problem sounds just like mine at the moment.

was the lenght of pipe straight from the tank to the lift pump?
can you remember what length it was/ size pipe?
or did you put a non return valve in too?
what about the sedimeter ? has this been by passed?
what about the pupply pipe was this renewed too?

just looking for a clearer picture of what to do/ what i need to buy

asking silly questions as i have a serious back injury and have restricted movement so the more infomation i can get the better, as keep getting under the discovery is very difficult.

if i can get all the bits i may be able to persuade a volenteer to give me a hand

any and all info/comments welcome

I ran two lwnghts of hose from the tank pickup and return to the fuel pump and return lines under the bonnet, bypassing the sedimenter on the way.

It ws a while ago now but I think the hose was 8mm bore, it came from halfords, they do not display it but have it available on a roll. I think I bought eight metres and had about a foot left at the end, I'd suggest you measure up using tape measure and add a couple of feet on.

I cut the existing fuel lines leaving about 2" of the rigid plastic and slid this inside the rubber hose, it was a snug fit. I then WELL tightened the jubilee clips so they were tight enough to "pinch" the hose, giving them a good tug confirmed that thet were not going to come off very easily.

I did not use a non-return valve but I note that others have used them, I guess I was lucky.

The hoses were run under the car, being secured to the normal fuel lines using cable ties every 6" or so, I left the old lines in place just so I could tie on to them.

I have had absolutely no starting problems since replacing the fuel lines in this way, once the heaters go off, turn the key and its running within ~2 seconds.

The most tricky bit was getting the lines from where I joined them near the tank / sender out to the chassis to clip them onto the old lines - the first time I just poked them through and I got a load of muck up the end - that will do the pupm no good at all so I flushed the hose and put a bit of tape on the end before trying again.

Hope this helps. If you want any addidional info, just ask.

great thanks for that,

when joining the pipes, you said you just slid the new pipe inside the 2" of the old pipe.did you put any connectors in or just pushed then together and used a jubilee clip?

sounds easy enough to do,and not expensive either.
did ask for price for fuel lines recently and told £90+ special order and 3 weeks delivery.
this i could get these pipes etc from most good car accessory shops.

did you have to bleed the system?
did you change fuel filter while you were at it?

have read a variety of opinions but would prefere to do the same way as been proven that works.

have you had any problems by passing the sedimeter?

sorry for going on but i like to know everything i need before i start a job as keep getting up and down is murder.

hi i,ve got a starting problem with my disco 300tdi,
it just will not turn over fast enough,then the battery starts to run
down so i have this every morning i have to jump it off a spare battery
i,ve got and the it does,nt turn it over as it should, i,ve changed the glow plugs well three of then i could,nt get the forth it,s an es and i did,nt want to mess with the aircon motor,it should,nt make that much difference changeing three should it??
any ideas what i should do when it,s run it has run it,s fine could drive to hell and back no probs,i,ve been told i could have a lazy starter
motor but it starts it,s doin my head in..
please if anyone,s got the same or had the same probs and what
i would be greatfull, thanks for reading, regards dereklcg
ps i,ve had the battery tested standing and running
a it,s putting out full wack????

dereklcg said:

hi i,ve got a starting problem with my disco 300tdi,
it just will not turn over fast enough,then the battery starts to run
down so i have this every morning i have to jump it off a spare battery
i,ve got and the it does,nt turn it over as it should, i,ve changed the glow plugs well three of then i could,nt get the forth it,s an es and i did,nt want to mess with the aircon motor,it should,nt make that much difference changeing three should it??
any ideas what i should do when it,s run it has run it,s fine could drive to hell and back no probs,i,ve been told i could have a lazy starter
motor but it starts it,s doin my head in..
please if anyone,s got the same or had the same probs and what
i would be greatfull, thanks for reading, regards dereklcg
ps i,ve had the battery tested standing and running
a it,s putting out full wack????

Click to expand...

I think I might know what the problem is.

As you said you have enough juice in the battery, so it's not getting to the starter motor. One reason this often happens is a bad earth. Check and clean as neccesary the following:

1. Earth connection from the battery to the chassis/engine;

2. The earth connection between the starter and the chassis/engine; this is where the problem is likely to be.

A quick and easy way to check if it's an earth problem is to connect a thick bit of cable onto the starter neg/earth side and then connect that straight to the battery. This will give the starter an alternative path - if it starts better, you now know it's an earth problem. If you've got any old solid core copper cable/flat twin& earth knocking about that'll do, so long as it's thick.

Hope that helps

Cheers
Dave

in reply to markw:

Yes, I just cut off the hard plastic pipes, leaving about 2" behind, slid the fuel hose over this stub and did up the jubilee clip, very tight. I gauged it by looking and tugging but my objective was to pinch the plastic pipe a bit to make sure that the new hose cannot easily come off, whilst not collapsing it to the extent that fuel flow is restricted.

I did bleed the system - I cracked open the nut on the outlet of the mechanical fuel pump and pumped the lever for an AGE until fuel came out, then I did it all up and started the engine (was just as difficult as before the repair), once it was running I did the naughty thing that is not recommended or endorsed by anyone sensible... slightly loosen each of the injector hoses in turn and let them "spit" just a tiny bit, then torgue them up again.

I'm confident that if I had gone for a drive, the injector bleed would not have been necessary, so dont consider doing it unless essential, the fuel mist ignites much easier than a whole bucket of diesel will.

I did not change the filter but since that time I have changed the entire filter and the housing/bracket thingy that it hangs on - I got the pair for £15 online, much better than the genuine price! I think it was a link somewhere on this forum that I followed to find the cheap parts.

I did this in late 2005 (see date on the original post) and the car still starts on the button, and now has 125k on it so I'm pretty confident that bypassign the sedimenter has caused no problems, then again, this is a town & towing car, it does not get dirty, I do use it on the local slipway but am careful to keep it dry!!, not least because I have watched my jetski trailer get corroded away.

If you are concerned about doing this work you might want to consider just fitting a non-return valve about 6" before the mechanical fuel pump, if your starting improves a bit then it would be safe to suspect runback and spend the time replacing the lines right through, I have never tried this though, I just bit the bullet, replaced the lines and it worked for me.