Fuel drains back to tank ... with a Big Twist

[shaby]

Hi all
I replaced diesel fuel filter on my 2012 D40 Spain built as fuel was draining back to the fuel tank and ute needed to be primed before it would start. Has not fixed the problem. It is an intermittent problem. Happens maybe once every few days - then twice in half an hour. Sometimes priming and starting only works when someone is priming and someone else is starting the ignition as the fuel seems to be draining super quick sometimes.

Here is the twist. I know when it is initially going to happen as when I go to start the vehicle it does not crank over for about 2 or 3 turns of the ignition key. It is as if the battery is dead. The battery is brand new so that can't be it. After about 3 attempts the car's starter motor then cranks over but it will not start until I prime the fuel filter. Fuel filter is canister style with 2 pipes and a plastic valve thingy all coming out the top - it is also new (RYCO).

Fuel line from tank to the fuel filter has been checked by mechanic and has no issue - according to mechanic no sign whatsoever of fuel leak...

Would love to hear what the brains trust think of this issue.

shaby

 

[Old.Tony]

The very first rule of fuel leaks in these trucks: overprime it. Don't stop at 4-5 squeezes when it's firm. Go all out - 20 or more. Let it build up so much pressure that diesel starts coming out of the leak - because that points you right at it.

 

[Simon Willems]

I've had a similar issue with an old Mitsubishi tractor, in my case it was a new battery which fixed the problem but not initially, I needed to use the tractor for a big job before it charged the new battery fully. Up to that point it was just as you described. What I'm wondering is if the low voltage is opening up the fuel circuit somehow when it.doesn't start properly and the fuel back siphon some how. Is the alternator putting out a good voltage?

 

[shaby]

A couple of additional points regarding the problem...and it has gone to 3 mechanics in the last month and none of them can find a problem with the fuel line.

1. It seems to be triggered more often by reversing before turning the engine off...but this may just be a coincidence
2. When I go to restart and there is no response at all to turning the ignition - so the starter motor does not even crank over (for about 3 or 4 attempts) the red light on the dash with a key inside a car (I think it is an immobiliser light) is on. When it starts normailly this light is not on.

 

[shaby]

The very first rule of fuel leaks in these trucks: overprime it. Don't stop at 4-5 squeezes when it's firm. Go all out - 20 or more. Let it build up so much pressure that diesel starts coming out of the leak - because that points you right at it.

Thanks Tony. I've been doing about 20 pumps and it works most of the time...if it doesn't then I have to get someone to be starting the ignition while I prime the fuel filter cannister...that has worked every time except 1 where an NRMA guy sprayed some stuff in the air intake and it started. He put me on to "Start ya Bastard" - bought a can but have not needed it as yet...they say to be careful using it with diesels.
Since reading your post I've been doing 50 pumps and it has worked each time...would still prefer a fix to a workaround...but a workaround at least gets me home...

I've added a couple of additional observations to the posts...

 

[shaby]

I've had a similar issue with an old Mitsubishi tractor, in my case it was a new battery which fixed the problem but not initially, I needed to use the tractor for a big job before it charged the new battery fully. Up to that point it was just as you described. What I'm wondering is if the low voltage is opening up the fuel circuit somehow when it.doesn't start properly and the fuel back siphon some how. Is the alternator putting out a good voltage?

Hi Simon
Thanks for your response. I've added an observation to the post thread, but you may be onto something. I've started noticing that each time it is about to not even crank over, the immobiliser light is on (car with key through it). Maybe the immobiliser does something to the fuel circuit like you are suggesting? Perhaps someone here knows about what an immobiliser actually does to the car (besides immobilise it)...

 

[Old.Tony]

Thanks Tony. I've been doing about 20 pumps and it works most of the time...if it doesn't then I have to get someone to be starting the ignition while I prime the fuel filter cannister...that has worked every time except 1 where an NRMA guy sprayed some stuff in the air intake and it started. He put me on to "Start ya Bastard" - bought a can but have not needed it as yet...they say to be careful using it with diesels.
Since reading your post I've been doing 50 pumps and it has worked each time...would still prefer a fix to a workaround...but a workaround at least gets me home...

I've added a couple of additional observations to the posts...

If you prime it that much, it should leak fuel out somewhere! There's obviously air getting in somehow, because it should not need more than 4-5 primes before it's firm and full of fuel.

 

[shaby]

If you prime it that much, it should leak fuel out somewhere! There's obviously air getting in somehow, because it should not need more than 4-5 primes before it's firm and full of fuel.

Hi Old Tony
No leak...first 5-7 pumps - the bulb is 'soft'. Then gets hard by 8. After that, each squeeze only depresses the bulb by about 1cm max...following you advice to do more than 20.
Didn't fail at all yesterday. This morning went to get my morning 'V'. Parked. Didn't central lock the ute. Came back and turned the key - immobiliser light came on and stayed on. 5 total turns before there was any response from the starter motor (then no immobiliser light). Had to go pump the bulb (50 times...seems to work). Was in the shop for 30 seconds max. So fuel drained back to tank in that short time. No evidence of fuel on the ground once I got moving again. It is becoming a conundrum wrapped in a mystery...

 

[Simon Willems]

Hi Old Tony
No leak...first 5-7 pumps - the bulb is 'soft'. Then gets hard by 8. After that, each squeeze only depresses the bulb by about 1cm max...following you advice to do more than 20.
Didn't fail at all yesterday. This morning went to get my morning 'V'. Parked. Didn't central lock the ute. Came back and turned the key - immobiliser light came on and stayed on. 5 total turns before there was any response from the starter motor (then no immobiliser light). Had to go pump the bulb (50 times...seems to work). Was in the shop for 30 seconds max. So fuel drained back to tank in that short time. No evidence of fuel on the ground once I got moving again. It is becoming a conundrum wrapped in a mystery...

Just a thought, if the immobiliser light is on, would this disable the fuel pump?

 

[shaby]

Yeah...maybe I'll repost in another section with that as the Lead question

 

[shaby]

OK ... I think I fixed the issue. One morning the ute got to the corner and then just stopped dead. It was as if it had just been turned off. I figured battery...which was correct - the positive bushing wasn't touching the terminal well enough. So I went and purchased a new terminal and attached that to the positive cable and Voila...the problem hasn't happened since. Still wondering what happens when an immobiliser is 'triggered' - how that leads to a drain of the fuel filter, but that is perhaps a question for another day. Thanks for your help and ideas folks.