The saga of the 1.5 dci delphi fuel pump!

[triumph2.5man]

80 bhp 2003 1.5dci 110k on the clock.
Thanks to CLIP i have known for some time that my fuel rail pressure was low (650 bar at 200rpm cranking speed - injectors disconnected, spare IMV in use), should be at least 1050 bar according to Delphi. Looked around for ages but could not find a pump locally so bought one from ebay - big mistake! Said to be low mileage, I fitted it but spent a week trying to start the car - tried everything. Suspected the "plumbers' nightmare" - an airlock but it was not to be. Gave up and refitted the original pump. Dismantled the ebay pump and found the reason -full of rust and clearly had water in at some point. The high pressure valves were rusted in. Luckily I paid only £30 for it. The seller did not respond to messages and ebay would take no action as quite a bit of time had elapsed. Buying injection equipment from ebay is risky (and I have several dud injectors to prove it!)

Off to the local scrappy and now several dci engines available. Picked one I could see was not seized. Dismantled it (easy job and easy to reassemble but watch those springs) and could see the rubbing surfaces were all good. Put the pump body in the vice and filled to the brim before fitting the cast iron end piece (that is where the high pressure is generated). Back in the car, 90 minutes by leaving the sprocket in place - chalk mark the teeth and belt to be safe but the sprocket did not move. All in all an easy job. Now the big moment - start! Fingers crossed..... Started second push and settled down to a smooth idle. A repeat of the CLIP test revealed 1305 bar at 200rpm cranking speed. At last a decent pump for £30! Good bye to the constant level 2 messages STOP injection fault (error code DF053) which I saw dozens of times when accelerating (but ignored and nothing ever happened!) Engine starts now within 2 seconds compared to 6 previously. A pleasure to drive!

Dismantled the old pump and was flabbergasted. It was totally worn out (although the low pressure pump at the front was all OK). The rollers which create the pressure were flat on both sides and I could see the roller carriers were also worn. Thinking back this problem probably started 3 years ago and it seems that several grams of fine filings (or swarf) have passed through the system with minimal difficulty. At the time of writing the car runs like a dream and ticks over like a watch. Clearly no swarf in the injectors and as the tank is nearly empty, probably not a lot in there either.
I have attached a few photos. The final pressure is obtained by two small "pistons" that are squeezed together by the rollers and these can be seen in one of the photos.. All this takes place inside the heavy end piece. It is interesting to see how the pump works by following the various passageways and through the IMV.

I will be writing an addendum to this post to explain why the filings have not stopped the engine or blocked an injector.
First photo is "rusty pump internals"
Second photo "high pressure valves fit in these four orifices"





Mike

[Stevie67]

Was this the ebay pump, or was this the pump you had running the car?
Your rollers look in worse condition than mine did, but mine wouldn't run.

[triumph2.5man]

The first three photos are of the useless pump from ebay. The last photo is of my badly worn pump.

Now, how come my engine has largely managed to run reasonably well for the last three years with so much swarf in the system with just the odd hiccup? We have all heard of cars (not just Renaults) that have been scrapped prematurely because of pump failure and swarf in the pipework. Why has this not happened to my old bus? Why is it not misfiring and leaking badly now?
Having closely studied the workings of the pump I think I can come up with a solution.
Although clearly not foolproof, the system is cleverly designed to resist such a situation.

Clean fuel is sucked into the pump low pressure inlet having just passed through the filter. The suction is strong and a lift pump is not needed.
The vanes of the low pressure pump boost the pressure to 5 bar and pass it on to the high pressure side via a drilling at the top. Some of the fuel leaks out and builds up inside the pump cavity to lubricate the front and rear bearings and this is where the swarf is collected as the parts wear. When the cavity is full, excess returns to the venturi .
Fuel (still clean) at 5 bar passes through the rear of the pump where it arrives at the IMV (the Inlet Metering Valve). The IMV has a fine gauze filter which will capture any large pieces of swarf or filings that might make there way to here. From the IMV fuel passes through the high pressure inlet and discharge valves where the pressure is ramped up to around 1400 bar by the small pistons sqeezed by the rollers. Then out through the end fitting to the rail. The fuel is still clean at this point and the exact pressure is determined by the needs of the engine controlled by the voltage at the IMV following input to the injection computer by various sensors. It all happens in the blink of an eye - faster than it has taken me to describe. Two seconds??

Returning to the fuel in the main body of the pump, it does contain filings or swarf from the roller path and the worn parts as seen in the above photo, (and in my case, a very large amount!) but these go out through the venturi where it mixes with fuel and bubbles from the injector leak-off pipes. This mixture is returned to the fuel filter when cold and dumped around the edge of the internal filter for reuse. This contaminated fuel must pass through the filter again before returning to the pump. Any swarf will have been removed by the filter. When the fuel is hot, the bi-metal strip in the filter canister expands allowing the internal ball bearing to drop and close the port to the filter. Leak-off fuel is then returned directly to the tank. The process then starts all over again and filings are removed from the fuel by the filter and so it continues. Clever n'est-ce pas Monsewer Renault?

Why then, has my car escaped the usual problems of leaking or blocked injectors. The answer is simple - I have always changed the fuel filter regularly. The current one is a genuine Delphi (the best to use -- shake it and the internal ball bearing can be heard rattling) and has been in place only a few hundred miles. May I suggest then that any vehicles that have suffered swarf damage have not had their filters replaced regularly? Now that my pump is no longer shedding swarf I am confident it will go on for many more miles yet and what little contamination is remaining in the system will soon be removed by the filter. I have considered an extra inline filter before the primer bulb and also one on the leak-off line to the tank but can't see the need. Replacing the Delphi filter in a year will ensure long-term reliability.
All the filters I have removed from my car, I have dissected and examined for filings. Same with injectors - I have dismantled many and found all but the odd piece of swarf. Every single injector I have examined had five clear spray nozzles.
The moral of this story (sorry to ramble on) is change your fuel filter regularly and use an original part. I must confess a bit of guilt here. What with all this work on the mark 2 I have neglected our mark 3 and have yet to change its filter (which has an internal heater). In fact the mark 2 now starts quicker than the mark 3. Time to plug in CLIP and learn how to use the Borneo3 system which is different to the Borneo2 in the mark 2!
No retirement for me....

Mike

[quaker@eircom.net]

Hello Mike...
I use the main dealer fuel filter ( renault part) and change every 20,000 miles. I cut the old one in half looking for metal filings but found nothing yet.
On inspection of the internals of this filter, it turns out that it is actually a Delphi filter. I did notice the ball bearing noise from time to time but never knew what it was until you described it on another post. Re the injectors...how much can you refurbish/fix these before you have to recode them.
rgds Maurice

[triumph2.5man]

Hello Maurice, the Renault original part filter is made by Delphi and is available from Ebay at a great saving! A non-original filter will not have the ball bearing but a similar plastic part and will not rattle when shaken.

About the injectors; I have split, cleaned, modified many without recoding them and this has worked well. I have swapped internals from known working Mondeo injectors to the Megane and rarely had trouble. The internals are all the same anyway. I do have the facility to recode but sometimes this does not work. "Code writing failed....contact techline!"
At the risk of repeating myself, my car is running like a watch and two of the injectors in use have not been coded. One has got internal bits from goodness knows where - a box of odds and ends on the workbench! It is handy to have a box of bits for the annoying occasions when small parts disappear and believe me, they certainly do!

I know the theory about how the fuel flow is measured at various pressures and the injection computer amends the timing accordingly. This was done to the injectors in your car when it was new. All well and good. But now 110k later (say), the flow pattern will have altered beyond belief. The needle and nozzle will have worn. The nozzle spring will have lost strength. The most sensitive part, the control valve will have worn resulting in excess leakage. The control valve spring (the long, thin one) will also have weakened. The coil will have changed Thus by now the flow pattern will have altered completely. What are the alternatives? Have the injectors recoded at great cost? I think not. Throw them away and buy an expensive new set? This is not my way. Buying injectors from ebay is a risk but I have got some good ones which are running well. That is the crux of the matter. As long as the car is running well, idling on all 4 cylinders, not smoking, all will be OK The proof of the pudding is in the eating!
A leak-off test is a good indication of condition. For an early 1.5dci the recommended method (CLIP command AC029) used on an engine with coolant over 60deg C revs the engine hard four times, then repeats ie 8 times in all. Leak off fuel is measured and any injector returning more than 35ml should be replaced. Instead of replacing the injector one could buy a new control valve which is where the cause of the excess leak is . You can get them from China for about £22. There are many difference reference numbers but bizarrely, they are all the same! Most folk fitting these valves (and it is quite easy) will not be recoding the injector.
Thinking of splitting your injectors? Give it a go....
Cheers, Mike

[Stevie67]

Hi Mike,
So if one sticks to the service intervals religiously as you seem to have done, how come the pump still went bad?
At some point did some of the injectors that you were talking about produce foam, and if they did, did they fail the leak off test.
I haven't opened up a fuel filter to see exactly how it works, but I suspect that the returned fuel having been filtered on its way from the tank will not be filtered again, will it?
Steve.

[triumph2.5man]

Hello again Steve. Glad to see somebody reads the rubbish I write!
I attach a pic of a dissected delphi filter. Here you can see the bi-metal strip leading to a nylon circular bit. This is where leak-off fuel returns via the spigot on the right. The ball bearing is inside this nylon bit. You can see that leaked off fuel drops down the side of the filter. Fuel to the pump goes out through the hole in the middle so you can see that the fuel is cleaned twice. When the bi-metal strip expands the ball bearing drops cutting off the leak-fuel and diverting it to the tank. Anybody with a later 1.5dci won't have this system but I don't know when the change was made. Any filter with plug and wires attached or 1.9 will not have this system. I notice the mark 3 1.5 has a heater in the filter housing.



I might be changing the fuel filter regularly now but that has not always been the case which could be why the pump has failed. Thinking back the trouble began about 3 years ago when starting from cold was difficult and filled the road with smoke - never seen owt like it! I suspected the glowplugs and they were all dud. Replacing them made no difference as the clouds of smoke continued.
I did a lot of fiddling with injectors until I found the offending one. Unmetered fuel was clearly leaking into the engine. I did not have access to CLIP then and was unaware of the filter problem. I carried out a series of basic leak-off tests but nothing like the recommended one - 8 heavy pushes on the throttle - with various results. Just connecting up and allowing the engine to idle is a rough guide but not the complete answer. yes I did see lots of foam. I think this is fuel mixing with air and gas from the engine.
I hope I have answered your question. How are things up in bonny Scotland. Bet you need good working glow plugs there this week!
Cheers Mike, in sunny Suffolk!

[Stevie67]

Thanks for the reply Mike, and yes I read all yours and a lot of others posts, I am on an learning curve with type of system.
I haven't had the time yet to investigate my filter, so thanks for the explanation and the photo.
I think then it is safe to say that once the injectors reach a certain age, they start leaking "air" back to the pump, this "air" causes sections of the pump to run un-lubricated briefly which causes the lack of high pressure and swarf over time. Any swarf created in the high pressure end of the pump is either returned for filtering or passed through the high pressure side to the injectors. I still think that I am heading in the right direction by returning my leak off fuel to the tank and returning my pump return to the filter, keeping the bubbles as far away from the pump all the time.
There is a sort of evil destructive symbiotic relationship going on here, the injectors kill the pump and in it's dying days the pump returns the favour and tries to kill the injectors.

Steve.

[triumph2.5man]

that's a fascinating theory Steve. Good luck with your plans and I am sure you will keep us informed. it's all in the book of experience.
Regards, Mike

[triumph2.5man]

stevie, I have today looked over the mark 3 1.5dci and thought you might like to see what changes Monsewer Renault made around the fuel supply - all part of your learning curve. You seem to have an insatiable appetite for Renault knowledge and area quick learner!

There have been quite a few changes, not least from Delphi to Siemens. (I hope it is for the better......)
The fuel filter contains a heater so the leak-off pipe runs straight back to the tank.
As there is no ball bearing or bi-metal strip, when the primer bulb is squeezed, it goes hard when the pump is full - just like and outboard fuel tank. That's how it should be!
Where the leak-off pipe joins the pump leak-off (on top of the pump and not on the side as mark2), there appears to be a one-way valve just before the venturi, to stop the reverse passage of air I believe. You can just see it in the photo. Another interesting change is a plug with two wires at the venturi junction and I have yet to find out exactly what the purpose of this plug is.
I ran the engine and could see large bubbles in the supply pipe but these do not affect the running. You are probably asking what about the leak-off pipe, any bubbles or foam in there? Impossible to say as the pipe is no longer transparent and connects to steel pipe for its journey to the tank. I suspect most cars have leak-off bubbles and if you can't see 'em, you won't worry about them!
The main supply pipe (which is of larger diameter than mk2) is transparent back through the primer bulb where it joins steel pipe.
Enjoy! Mike

[Stevie67]

Interesting stuff, with the system in my Megane, when you use the primer it seems to pressurise the feed to the pump obviously, but it also pressurises the return pipe from the pump to the filter, but it forces fuel up the pipe in the wrong direction. Because of this we have to prime fuel all the way backwards up the return pipe to the injectors, with my mod this is no longer necessary, this is why I want to develop a bleed valve at the pump because there is nowhere for this air to go. You say your primer goes hard, when it is hard, if you where to keep pressure on the primer would it eventually deflate? If so, I suspect you are forcing fuel through your pump and all the way back to the tank. Your one way valve could be to stop you priming the return pipes from the injectors? Yes, I agree that most diesel engines probably produce bubbles, the difference is how they deal with them. One observation that I made after my conversion was that when bubbles come from the injectors, they get passed to the pump, although it doesn't actually go inside the pump, in the plastic fitting where it joins, it meets return fuel from the pump, this is where the foam is made.

[Stevie67]

I eventually got round to cutting open the Fram fuel filter that was fitted to my 1.5dci. Guess what....ok you got it, it was full of metal filings, and another guess what....there is no ball bearing,but you already knew that, however there is a heat sensitive valve, it uses a small spring steel disc, when cold the disc is concave, when warm the disc pops itself to convex. It is only a tiny movement, but it is enough to open and close the diverter valve inside the filter casing. So, both methods should work as well as each other. The metal disc, when sat on the workbench was concave, when sat in the palm of my hand it went convex, so it is very sensitive to the temperature. Seeing this behaviour made me realise that this disc, or the Delphi bi-metallic strip don,t just wait for the fuel to heat up then dump it all back to the tank, but rather they continually flutter to keep the fuel at a predetermined temperature , if the fuel is getting too hot, they introduce a little cooler fuel from the tank, if the fuel gets too cold it will just recirculate the fuel between the filter and the pump.

[quaker@eircom.net]

Hello there..
Where the overflow diesel leaves the HPP (Meg2 1.5dci 2005), it at first flows through a plastic housing which is attached to the back of this pump, where it is then joined by an overflow pipe from the injectors. It seems there is a reduction in the internal diameter of this housing just where the injector overflow joins it, to create a venturi effect. This venturi effect causes the overflow from the injectors to be effectively sucked in here at this junction, to join the overflow from the HPP.
Could this suction effect possibly cause some bubbles to come from the injectors when they are electronically pulsed ( without injecting any diesel) to relieve/reduce rail pressure ( eg when trottle suddenly released )?
rgds Maurice

[Stevie67]

Hi Maurice,
At first I thought that the returned fuel from the injectors was sucked in by the venturi effect as you describe, however when you see the leek test it is obvious that the fuel is under enough pressure that any venturi effect would be irrelevant. I don't think the injectors can be pulsed without them injecting fuel, I may be wrong, but I think pressure is released from the rail via the pressure regulator solenoid.
Steve.