Fuel runs back into tank

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Dazza63

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I have had this issue stop me a couple of times in my 2008 D40 Spain built when I park it on a steep hill. The fuel runs back into tank and you have to try and pump it back up to filter. Also now it starts first up of a morning and idles fine but by the time I get my seat belt on it cuts out and you have to wind it for about 5 - 10 seconds before it starts again. Any ideas what that is.
Is it possible to put an electric fuel pump inline so if it runs back into tank I can flip a switch and it pumps up. Or can I put a one way stop valve inline or even up near fuel filter would that work or help. Open to anything the starting and stopping of a morning is slowly getting more constant but only just started in the last couple of months.
Any ideas help greatly appreciated.
Thanks for any help.
 

bods

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Have you changed the fuel filter recently? Normally that is caused by a slight air leak somewhere causing the fuel to drain back. I don't know what sort of primer you have for your fuel filter, but there has been mention on here of the rubber diaphragm in the primer splitting and causing air to be let in. From the factory they have non return valves fitted so fuel draining back shouldn't be a problem.

When the motor is cold, open the bonnet and give the primer a few squeezes, it shouldn't take any more than maybe 2 or 3 before it gets noticeably harder to push. If you keep squeezing it once it gets harder, you may notice fuel leaking out of wherever the air is leaking in...
 

Dazza63

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Thanks bods Ill give it a try info greatly appreciated...I did do service and did fuel filter about two weeks ago but problem was before that but Ill check hose clamps and try priming looking for leaks....
 

Dazza63

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It wouldn't have anything to do with the suction control valve ???????
 

bods

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It could, but that's not usually an issue if you are parked on a hill... Generally that will cause it to start and rev up and down, not always stall, especially when cold as the computer is trying to regulate fuel pressure but the scv is moving too slowly... Normally with a scv it will still start and idle again straight away but revs may fluctuate and stall again.

Yours sounds for sure like you're getting air into the system somewhere...

I should add, you can add an electric lift pump, however as has been mentioned on here before, you really need a bypass set up too in case the pump fails and causes a fuel line restriction. I have 2 fuel filters on my D22 (a 30 micron pre filter plus the factory filter) and haven't had any issues with fuel draining back to the tank even when it used to sit for 2 weeks while I was away for work, so there's definitely something going on with yours.

Do you have the big metal filter head which the filter screws on under and has the primer on top or have you got a separate primer bulb and an inline sort of style filter?
 
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Dazza63

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No bods I have the type with the pipes coming out the top I have put nes hose clamps replacing factory ones. Just strange it has stared in last few weeks. Always started first hit of the key and away she goes but this is a new issue Ill have to check all fuel lines and hoses then to see if it has splits or leaks anywhere. Great idea about the by bass setup too brilliant. As usual to all who give great help many thanks Ill let you know if I find anything again thanks for the info greatly appreciated.
 

Old.Tony

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I'd give the fuel primer bulb a few squeezes in the morning and see how many it takes for the bulb to get firm.

Once it does, if it takes more than 5-6 squeezes, I'd keep squeezing it, because you'll pressurise the filter and might discover the leak.

On my car, the mechanic didn't install the water sensor (bottom of the filter) properly and caused the fuel to run back to the tank overnight. It would start because there was still a filter full of juice, but it would cut out a couple of seconds later. Turns out the mechanic had turned the sensor just enough for it to feel firm, but you have to turn it so that its electrical connector lines up with the black knob above it.

Otherwise, it could be cracked hoses, cracked primer bulb etc.
 

Dazza63

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Thanks guys Ill check the water sensor as I had not all that long changed the filter so may well be thanks Tony I will check first thing tomorrow .
 

Maddo71

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Hi Dazza,
I have a 2008 D40 and when I park nose down a steep driveway I have a similar issue. Happens when I have less than quarter tank of fuel. It is not that the fuel drains back as mine starts ok but like you mentioned by the time you put belt on etc it has used the fuel in the lines and I have to get it on a level surface and prime the filter. Only happens when low fuel and steep drive nose down.

So that leads me to think it is internal pickup and tank design. As I don't let my tank get that low it normally is not a problem.

Hope that helps.
 

grumpy too

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Think you might have an air leak in the suction line or from the filter back, have struck this before a few years ago with a farm vehicle not sure if it was a Navarra but it took some finding as there was no external fuel leak, it just let air in very slowly and allowed the fuel to fall back into the tank overnight which required priming or as the bosses wife did cranking it over until the battery went flat every day.
 
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tweak'e

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Hi Dazza,
I have a 2008 D40 and when I park nose down a steep driveway I have a similar issue. Happens when I have less than quarter tank of fuel. It is not that the fuel drains back as mine starts ok but like you mentioned by the time you put belt on etc it has used the fuel in the lines and I have to get it on a level surface and prime the filter. Only happens when low fuel and steep drive nose down.

So that leads me to think it is internal pickup and tank design. As I don't let my tank get that low it normally is not a problem.

Hope that helps.
i know this is late but it may help someone.

running out of fuel when on steep angles and low fuel is a tank issue.
i believe the fix they did for it was to change the angle of the return pipe in the tank. i presume that it would put fuel next to the intake pipe. good for not running out of fuel but lousy for fuel cooling.
 

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