Non return valve on fuel line

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TRANSPORTER
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Non return valve on fuel line

Post by TRANSPORTER »

Hi guys, 1998 406 2.1 td, new glow plugs all working, tank pick up cleaned, fuel filter replaced and fuel filter housing cleaned out, fuel line changed from bulkhead to first section of clear pipe including new primer bulb.
So I’m thinking, we’ll going to fit a non return valve onto my fuel line after the primer bulb and before the fuel filter reason for this is due to poor starting in the mornings after all these changes. My primer bulb doesn’t stay firm overnight. I did have a lot of air in the system but since swapping out that part of the fuel line and primer bulb the air has now gone.
But when starting in the morning I give it a couple of go’s on the glow plugs before cranking, she fires for about a second then stops, then it’s bonnet up, a couple of pumps of the primer bulb and she starts. I can also get her started if I time a boot full of throttle just as she cranks but If I time this wrong it’s the primer bulb method.
Now the only parts I haven’t changed are the spill return lines, but they all look in good condition with no signs of wear or leaks.
As for the non return valve what are your thoughts on fitting one to see if it stops the obvious drain back of fuel to the tank?
Could the fuel be draining back overnight through the return pipe to the tank and not back through the feed pipe????
GingerMagic
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Re: Non return valve on fuel line

Post by GingerMagic »

I'm no expert, but I was under the impression that the fuel would only go back towards the tank if air was getting in therefore pushing the fuel backwards?

I guess you could fit the valve in various places to help locate the guilty party..
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Re: Non return valve on fuel line

Post by TRANSPORTER »

You are correct mate, air must be getting in, or there is a sting vacuum dragging the fuel back away from the fuel pump, so the theory is to fit the non return valve in a hope that it temporarily solves the problem.
I’ve a Lucas pump, driven by the cam belt and from what I have seen on the net the fuel stop solenoid is buried in the fuel injection pump and required drastic action to reveal it, is this correct or was I watching something completely wrong? As I’m also thinking that maybe the stop solenoid may not be closing fully thus allowing the fuel to flow backwards.
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Doggy
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Re: Non return valve on fuel line

Post by Doggy »

I agree with GM on this one, the problem is almost certain to be a minor leak between the primer bulb and filter or filter to injection pump. These typically aren't serious enough to let fuel escape, but let air in allowing the system to partially drain back to the tank. N/R valve shouldn't be necessary and any additional joints/fittings may impair the already marginal suction performance of the pump at cranking speed.

Is it spinning over at a reasonable rate?
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Re: Non return valve on fuel line

Post by TRANSPORTER »

Hi and thanks for the reply, yep she spins over fine with a good turn of speed on the starter, this morning I tried a quick experiment. Before starting i pumped the bulb 9 times before it got hard, I then done a single cycle of the glow plugs and she started like new, so definitely fuel pressure related.
I have looked for new clear pipes but Peugeot no longer hold any parts for the fuel system and if I go 2nd hand I might be facing the same problem.
Does anyone know where the stop solenoid is located on the fuel injection pump? Is it easy to get to?
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Re: Non return valve on fuel line

Post by TRANSPORTER »

Quick experiment tonight, had the old girl running for a little while on the driveway. Stopped engine and used one of my brake line clamps to clamp off the fuel line it’s one of the ones I replaced from the bulkhead to the first clear pipe to the fuel filter.
Come the morning I will see if she fires up first turn of the key, if she does then I’ll know a non return valve will temporarily solve my issue and then I can look from that clamp back down the fuel feed pipe from the tank for the air leak
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Re: Non return valve on fuel line

Post by GingerMagic »

I was going to suggest the same thing but with mole grips - you could try to stem the flow at a given point to see what happens the next morning....
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2019 Citroen C3 something - the wife's
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Re: Non return valve on fuel line

Post by TRANSPORTER »

I think mole grips might be a tad over kill :) the old brake fluid clamps ( plier style ) are a bit gentler on the rubber fuel hose. I’ll let you know my findings in the morning
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Re: Non return valve on fuel line

Post by TRANSPORTER »

Ok so very cold last night and I had clamped the fuel line as I said in the last post, so this morning I went out and done one cycle of the glow plugs and started her up, just a turn of the key no throttle, started straight away with no hesitation, whipped off the clamp and got the kink out the pipe. So tomorrow I’ll fit the non return valve as that will hopefully sort the problem👍
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Doggy
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Re: Non return valve on fuel line

Post by Doggy »

Well done, sounds like good progress there. 8)
2002 HDi 2.2 Exec Estate, (2008-12) (wonderful)
2003 HDi 2.2 6-speed Exec Estate (2012-19) (also a gem)
2009 Citroen C5 2.0 HDi VTR+ Estate (godawful heap)
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2007 BMW E91 325i touring (slower smoother quieter)
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Re: Non return valve on fuel line

Post by TRANSPORTER »

Fingers crossed, still doesn’t help me with the actual reason for the drop in pressure in the fuel line and the starting problems caused by that, but atleast fingers crossed I’ll have a cod morning starter without the need to pump the primer bulb
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Re: Non return valve on fuel line

Post by PeterN »

Does it have a fuel heater on the gearbox end of the head? That engine in the XM did and they used to go porous and let air in.

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Re: Non return valve on fuel line

Post by TRANSPORTER »

Not too sure about the heater on the gearbox end, what should I be looking for? As for the one way valve, I’ve fitted it and it worked great for the first morning but then the next morning it fired up and ran for approx 2 seconds then cut out. I pumped then primer again approx 10 times to get it solid then turned the key again.
It took a good few turns to get started again but once going drives like a train.
Quick question, once primed and running should the primer bulb stay hard or be pretty squishy?
The only thing I can think of changing out next is the spill return pipes ( leak off pipes ) but they aren’t showing any sign of leaks so I’m doubtful they are the problem,
And if they are then how come I need to prime the primer on the feed side, would the fuel not be going back to the tank via the fuel return line to the tank?
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Doggy
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Re: Non return valve on fuel line

Post by Doggy »

Can't remember the exact layout, but any minute leak in the feed side, filter, filter to pump line will do it. There may be an interconnection between the leak-off pipes/return line and the filter as well

You are probably draining the injection pump each time this happens, I have heard of this damaging HDi HP pumps as the fuel is also the pump lubricant. I believe your injection pump is similar, but don't honestly know.
2002 HDi 2.2 Exec Estate, (2008-12) (wonderful)
2003 HDi 2.2 6-speed Exec Estate (2012-19) (also a gem)
2009 Citroen C5 2.0 HDi VTR+ Estate (godawful heap)
2008 BMW E91 330i touring (great fun - murdered by a reversing SUV)
2007 BMW E91 325i touring (slower smoother quieter)
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Re: Non return valve on fuel line

Post by TRANSPORTER »

Yes the pump is lubricated by the diesel so Im very careful about not turning it dry so to speak, that’s why if she doesn’t start straight away I’m pumping that primer bulb to put fuel back in the system.
I’ll have a good look at the pipe layout and routing to see if I can work out the return journey of the fuel, I’m sure it doesn’t mix with the feed pipes though.
I don’t suppose you know the location of the stop solenoid?
I’m also looking in that direction, but even if that was opening overnight surely the non return valve fitted and the non return valve in the primer bulb would stop the fuel pressure dropping overnight
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