Hmm.....interesting comment on the fuel heater Peter.

(Yes, air ingress is almost definately the issue, just a matter of finding it). I've made up a transparent link from the output of the pump/filter to the injector pump that I intend to use as a diagnostic aid. I had a couple of spare bosch connectors.

The problem is, is that it's not very easy to bypass.

Unfortunately the feed to it, from the tank, uses quite hard black plastic tubing that is heat shrunk onto it.

(As mentioned previously, I replaced the output from it to the primer/filter housing with some clear tube and used copper wire around the output of the heater to tightly bind it. (The other end uses a propietary (Bosch) fitting that is a push fit onto he pump/filter).

Any ideas how I could bypass it as a diagnostic aid ? The only way I can think it to cut the black tube and somehow rig a connection from the cut to the pump/filter housing.

I assume the hard black plastic tube is installed with a special tool/heater as it's also bent where it needs to be and maintains shape.

(I had toyed with the idea of having a small test tank of fuel, under the bonnet, fed straight into the injector pump !!!

I think the only option is to cut the pipe, can you get some flexible pipe to slide over it? or a length of clear plastic pipe would be even better, you have the diagnostics in place for the next time! If you can't get some the right size, can you find a bit that will fit inside it, or a metal section with plastic at each end - I'm sure you can find something.

Vent pipes? IIRC the diesel has a red filler cap(vented)and petrol a non-vented black cap(for evaporative emissions).The pipe from the top of the tank has nothing to do with tank venting whilst running-it is there to get air out of the top of the tank whilst filling and for this reason the filler nozzle should be put as far into the filler as possible to avoid the venting air.

Oh dear, back to the drawing board. It seems certain from your last comments that the problem is due to air ingress, why it doesn't do it from cold is puzzling, the only thought I have is that the leak is occuring in something that expands when it gets hot.

The only way you can be sure to find the leak is to replace sections of the fuel line with clear plastic, starting as far back as you can get to make sure the fault isn't at the tank end. You could try either side of the primer pump and then the filter, at least that will tell you where abouts in the system the problem is.

If you can park the car for a while on a steep hill, facing downwards, so that the tank is higher than the engine - you might be able to see a leak.

Peter

Just a thought Peter.

When I get to town, maybe I'll pull the inlet of the primer pump/filter off. I assume that oher than a little residual fuel, nothing else should come out as the (inlet) one way valve should stop this.

I wish I had one of those bulb primers that I oculd put in circuit.......ebt

You won't get a fuel leak unless you put the system under pressure i.e. park on a hill, as the transfer pump in the injector pump is drawing fuel in so the whole system is under a vacuum. Forgot about your clear pipe,

If there are no bubbles when it won't start from hot, I would think there are only two options, either the transfer pump has lost efficiency, although I have never heard of that happening, or there is a restriction in the fuel supply which it can't overcome, the only way you can check that for sure is to run the engine from a container of fuel under the bonnet.

Peter

Yes Pete, I had (and will) consider that). I think I have worked out a way to route the incoming diesel from the tank direct to the injection pump. I need to ensure however that the tube I use is full of fuel, as there will be no primer in circuit. As always, I'll keep you posted.....

If you have a good battery you should be able to start it without priming, it will take a while to draw the fuel up but it should do it. If you can jack the rear up it will help.

I wonder if you have an obstrution in the supply line? Tank filter perhaps, Can you disconnect the pipe and blow it through to the tank with compressed air.

Well ,that's a good start, a pump leak is possible but the fuel is under presure once its inside so it should be leaking fuel if that were the case. I think it uses a Lucas pump doesn't it? Bosch pumps suffer if the injector leak off pipes are leaking. The only possible pump fault I would think could cause the problem would be a worn transfer pump, but as I said, I have never heard of that problem although it is of course possible, I would remedy that by fitting an external electric pump.

Peter

In the unlikely event of that being the problem, you don't have to worry about pressure regulation as surplus fuel goes back to the tank via the return pipe.

Many years ago I used an SU electric pump on a Morris Oxford that I had fitted a diesel engine to.

Peter

No problem. Later type pumps are of the 'through flow' type, well I say later, probably since the '70s, the idea is that there is a continual flow of fuel through the pump, this makes it much easier to start again if you run out of fuel and also allows air to flow back to the tank without going into the pump, but of course if there is enough air ir will still stop it.

If you look on the top of your pump you will see an inlet pipe at the back, and at the front near the throttle lever there is the return pipe, the leak off from the injectors is also connected to it.

As I said before, I would be very surprised if that is the fault - but stranger things have happened. I have been running diesels since 1959 and have never had that problem, although the early ones didn't have that arrangement and if you ran out of fuel you had to bleed the whole system through which you were lucky to do without flattening the battery, but they did have a lift pump on the engine so you got a fuel leak rather than an air leak.

Peter

Peter, whilst waiting, a couple of things sprang to mind.

In a "flow thru" transfer/injection pump, what causes the back pressure felt at the priming pump when depressed a few times. (Would it be the engine stop solonoid ?)

If the ignition was on, should I normally be able to pump, using the primer, feeling no back pressure, as the fuel would simply flow through the injector pump back to the tank ?

Just a thought.........ebt

Just advising that bulb primer and one way valve arrived this morning.

I will try installing the one way valve between the injector pump and the priming pump/filter housing first. If this solves the fault, I will assume I have a leaky valve in the priming pump.

Unfortunately it's -15c outside at present and might be for a few days. As soon as it warms up, I'll install it.............ebt

OK, braved the -19c weather this lunchtime and installed the one-way-valve between priming pump and injection pump.

Now waiting for run to town this week to see is it still fails on a hot engine. I REALLY will be non-plussed if it still does and maybe then the only resolution will be to fit a 12v fuel pump in the same place (after removing the one-way-valve).

However, I will still elimate the priming pump/filter as I now have a bulb primer in my greasy hands !!

Will advise..............ebt

(Is it possible to post photos/jpg's here at all ?)

That doesn't sound to bad for that temperature, my son has one of those engines in his P100 pick up and that's a pig to start at anything near freezing . I have recently bought a Peugeot 406 Hdi diesel and that starts instantly at below freezing without glow plugs! It also has a diesel fired auxilliary heater - fantastic.

Peter

They do have glow plugs but don't generally need them, my glow plug light shows for about a second but if you just get in and turn the key it starts almost instantly.

The reason is that modern common rail and a few previous to that are direct injection, the fuel is injected direct into the cylinder so there is no heat loss as with your engine where the fuel is ignited in a seperate 'swirl' chamber in the head, by the time it has been pushed through a small opening into the chamber and has 'swirled' around in it, to give a good mix, it has cooled significantly and needs the added heat from the plugs.

For years I have fought shy of entertaining such an engine as faults are not easy to diagnose and repair, I have been running Citroen XM td's for the last 15 years, fantastic comfort and space plus 50 mpg on a journey, they have IDI engines but very good ones, about the best made I reckon, good for at least 300,000 miles and super low down torque with the 12 valve head - you do have to use the glow plugs though!

This Peugeot Hdi engine is based on the previous XUD engine as the the XM one, When I was looking at the Peugeot's I noticed that there were quite a few advertised with in excess of 300,000 miles recorded, that did a lot to inspire my confidence. As you can't effectly repair them without the aid of a diagnostic code reader - I have relucantly purchased one.

I have always repaired my own cars but at 71 I don't bend as easily as I did but am hoping to keep it up as long as possible.

Peter

On an IDI engine the swirl chamber is machined into the head and then almost blanked off by an insert, leaving a very small aperture for the air to enter, that's what causes the swirl, the pumping friction loss is partly what gives lower efficiency from the IDI, it also causes heat from the compressed air to be absorbed by the metal and water surrounding the chamber. The fuel is injected into the air in the chamber then the burning gas has to go back through the orifice back into the main part of the cylinder - more friction loss.

If you look at an IDI injector it is quite short as it only has to reach the swirl chamber which is above the cylinder, on a DI engine the injector is much longer as it injects the fuel directly on the the top of the piston, which also has a swirl chamber built into it.

very old diesels were all direct injection but the fuel couldn't be made to mix effectively above about 2000 rpm, the IDI engine was introduced in the late '50s to make an engine suitable for car use, one of the first being the Perkins 4/99 which gave 43 bhp at 4000 rpm. I fitted one to a Vauxhall Velox in 1959. The development of very high pressure injection now allows direct injection at reasonably high speeds.

Yes, your Astra would be a common rail DI engine, 10% or more efficient then and IDI and as a result generating a lot less heat.

Peter

Well done, hope it lasts.

You'r welcome