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Discussion Starter · #1 ·
Hi guys hope you are all keeping well. Have not been on for a while but am out of ideas with this one.
This is a 2004 54 plate Kangoo 1.5Dci 70 and the problem appears to be air getting in to the fuel lines. If you pump the air out with the bulb it goes out through the tank return pipe and once the air has gone the van starts and runs perfectly but once you switch off and check the air is back and it will not start first time but it does second attempt even when you do not pump the air out. The air is not coming from the tank but looks like its coming from the pump return to the filter. I have done a leak off from the injectors which all looked perfect and blipped the throttle a few times to make sure there was no air coming from them. I have replaced the fuel filter, crankshaft and camshaft sensors still no joy. I also put some grease on the connectors just in case it was sucking in air The van runs perfect with no issues once started and no engine management light. Just for a bit more info the fuel pump is a Delphi Part No 820005722s I add this as i was told it was the pump but is it as they are damn expensive. Any ideas?
 

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Super Moderator Technical Supremo Platinum Member
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You are describing perfectly a leak somewhere in the fuel feed system.
Pipes to fuel filter is a favourite..grease can help.
Worn pipes..anywhere they may have rubbed?
Injectors leaking...leak test okay so should be okay.
Return pipes from injectors...broken connector?
Worn primer pump..check the back side?
 

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Discussion Starter · #3 ·
You are describing perfectly a leak somewhere in the fuel feed system.
Pipes to fuel filter is a favourite..grease can help.
Worn pipes..anywhere they may have rubbed?
Injectors leaking...leak test okay so should be okay.
Return pipes from injectors...broken connector?
Worn primer pump..check the back side?
Thanks for that I realise that is exactly how it sounds but the amount of air I am getting in would surely be noticeable. As you without doubt know the pipes are all clear. So I think the feed from the tank is good as no sign of air coming in that way which would notice as you squeeze the air out with the primer pump as you are sucking from the tank. All the connectors seem good as they were removed to grease them. Although thinking about it I suppose there could be a leak in the return pipe from the injectors as that has 4 tees in it. Just to also help if you pump the air out none gets in until you start again even after 3 or 4 days so the non return valve in the primer pump seems ok. It does not help that system sucks rather than being under pressure so its possible to have air get in and fuel not getting out. Will have another look tomorrow Thanks and all the best.
 

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Super fantastic Mod Technical Supremo Nice Guy
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Sure Glow plugs are OK
 

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Discussion Starter · #5 ·
Sure Glow plugs are OK
Thanks for the reply. Yes when this all started some time ago I thought the same thing and sure enough 2 dead glow plugs on cylinders 1 and 3 which were changed also tested them before I put the new ones in. Also tested the the power delivery for all 4 which was good. Sorry could have said that in the original question. But thanks for taking the time to ask. All the best.
 

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Discussion Starter · #6 ·
You are describing perfectly a leak somewhere in the fuel feed system.
Pipes to fuel filter is a favourite..grease can help.
Worn pipes..anywhere they may have rubbed?
Injectors leaking...leak test okay so should be okay.
Return pipes from injectors...broken connector?
Worn primer pump..check the back side?
Hi there again, as you suggested checked for leaks. What I did was blocked the return to the fuel tank so that I could put some pressure on the filter onwards. So with this blocked squeezed the pump until it went solid and do mean it was quite hard so there was a fair amount of pressure there, unfortunately no leaks and it was holding the pressure as I pulled the plug off diesel shot up in the air. So I would think that should be ok and also proves the non return valve in the primer pump (maybe) I cannot think of a way to put pressure on the feed from the tank but I have never seen air in that line. Do you think this was a good test or is there anything else I could try. Thanks and all the best.
 

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Super Moderator Technical Supremo Platinum Member
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It does not help that system sucks rather than being under pressure so its possible to have air get in and fuel not getting out.
That's exactly it and why it can be so frustrating finding where.
The fuel feed system is under negative pressure, a partial vacuum.....fuel cannot escape from a minor leak so no obvious signs. But air can get in which breaks the vacuum and lets fuel run back to tank
 

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Discussion Starter · #8 ·
That's exactly it and why it can be so frustrating finding where.
The fuel feed system is under negative pressure, a partial vacuum.....fuel cannot escape from a minor leak so no obvious signs. But air can get in which breaks the vacuum and lets fuel run back to tank
You are telling me frustrating. Correct me if I am wrong here but I believe that the system is self bleeding to a degree. In as far as its possible for air to get in from the tank I mean with diesel fuel sloshing around in the tank I would have thought that a few bubbles could end up going up the feed line. So I would have thought the air should go back via the fuel filter to the tank in the return line, well that is what I thought. That apart I do not know how much of a vacuum should be coming from the pump as if I do not evacuate the air from the filter you can see the fuel the level in the feed pipe to the filter so when you start the engine it sucks the air back into the filter quite slowly is this normal? Unfortunately you never look at these things until there is a problem.
 

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Every fuel tank should have barriers inside to minimise movement of fuel.
Pick up of fuel is from the low point to avoid suction of air bubbles.
And then, air is much "thinner" then liquid fuel. Where fuel can not pass, air will.
 

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Discussion Starter · #10 ·
You are telling me frustrating. Correct me if I am wrong here but I believe that the system is self bleeding to a degree. In as far as its possible for air to get in from the tank I mean with diesel fuel sloshing around in the tank I would have thought that a few bubbles could end up going up the feed line. So I would have thought the air should go back via the fuel filter to the tank in the return line, well that is what I thought. That apart I do not know how much of a vacuum should be coming from the pump as if I do not evacuate the air from the filter you can see the fuel the level in the feed pipe to the filter so when you start the engine it sucks the air back into the filter quite slowly is this normal? Unfortunately you never look at these things until there is a problem.
Thinking about this I may have answered one of my own questions. I realised that that the vacuum from the pump sucks in fuel from the filter and then the regulator valve sends the excess back to the filter so the suction on the fuel feed from the tank would be quite small I think? as it only needs to replace the fuel that engine has used. I do not think this helps me but but I am trying to put a logical solution onto an illogical problem.
 

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Super Moderator Technical Supremo Platinum Member
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One of the issues is that the HP pump cannot suck air.
Sucks fuel really well but not air...hence the need for the priming pump...to fill the lines.... and starting issues if air gets in.

Can't offer much more then find the leak...wish I could.
 

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Discussion Starter · #12 ·
One of the issues is that the HP pump cannot suck air.
Sucks fuel really well but not air...hence the need for the priming pump...to fill the lines.... and starting issues if air gets in.

Can't offer much more then find the leak...wish I could.
Thanks. Bear with hear as it may help someone else if not me and it may have bearing on my problem. Perhaps someone far brighter than me (not hard) can confirm or not. As far as can work out the HP pump sucks fuel in from the filter and then the regulator sends the excess back to the filter, so to the fuel is basically doing a circle. A very small amount is drawn in from the tank at this point as when the fuel vacuum rises inside the filter the vacuum increases on the line from the tank. So far any air in the filter stays there but as the fuel temperature increases as it does in a HP pump this hot fuel is going through the filter. Now as the temperature increases a bimetallic valve in the filter opens (do not buy cheap filters) and sends fuel back to the tank via the return line and so any air in the filter is sent back to the tank. Hence this pulls cooler fuel from the tank which cools the pump. So in what I am thinking the only time there is a good vacuum on the feed pipe is when that valve is open. So is this the reason I have never seen air in the feed line? .
 

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If you have a injector with excessive leak off you get a lot of air coming back a leak off test may tell you something.
 

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Discussion Starter · #14 ·
If you have a injector with excessive leak off you get a lot of air coming back a leak off test may tell you something.
Thanks Ralph. That is the problem with these epic problems you can miss part 1. Yes I have seen that before that worn injectors can push a lot of air back. But unfortunately that has been done and surprisingly all 4 past with flying colours.
But thanks for trying, all the best.
 

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Discussion Starter · #15 ·
Fixed ? since I changed the cam sensor I was unable to use the van for a couple of days so from looking it did not seem any different but at the moment it now starts first time with no problems 15 times so far and is that is different. The only other thing I have noticed is the air in the pipes has changed when this first happened it looked like foam going round the pipes about 5cm in length that has stopped you still get the odd bubble but from what I have seen that is normal I have no real explanation except this is only a theory if the cam sensor was faulty it could send the injectors the wrong timing and the engine compression is overcoming the pump pressure and forcing air back into the injector when it opens which could push back down return pipe. Very likely rubbish but I cannot think of anything else to explain it.
All the best and thanks for the help.
 

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Transparent fuel lines from HP pump to the engine, I'we seen many times something like bubbles. But engines were fine, running nicely.
No way that engine compression can push fuel back through the injector. Injection is an electric valve. Opening and closing depends only from signal from ECU.
Even if opened at the wrong time, fuel pressure is much bigger then cylinder pressure.
 

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Discussion Starter · #17 ·
Transparent fuel lines from HP pump to the engine, I'we seen many times something like bubbles. But engines were fine, running nicely.
No way that engine compression can push fuel back through the injector. Injection is an electric valve. Opening and closing depends only from signal from ECU.
Even if opened at the wrong time, fuel pressure is much bigger then cylinder pressure.
As I said probably rubbish but would the ECU not get the timing from the cam sensor I have no idea where it was coming from then.
 
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