Mk7 won't start no fuel

[Rossgal]

Hi all,

New to this forum, so hope someone can help!!

I have a 2008 115 2.4 with a starting issue, no codes showing although management light is on when cranking.

Breif history is that engine was running, taken out to sort out broken glow plugs in head, now won't start. Seems as though no fuel is going through the fuel pump, is there an old fashioned solenoid or something that would cause this?? Or something electrical?? Is there any way to test the pump?? I have tried priming the system many times to no avail.

Any help most appreciated. Thanks.

[knobby1]

No need to prime a Mk7 TDCi....were the injectors removed?? If so did they go back in the same cylinders..??

The TDCi pumps rarely fail.... and cracking a fuel line or similar to bleed the system will stop the PCM from operating the injectors due to low fuel pressure. Might pay to check the PRV to see if it is not blown.

Lord Knobrot

[Rossgal]

Injectors were out and went back in same cylinders, so fuel system was emptied.

It is though there is no fuel getting through the pump no matter what I try. How would I check the PRV? Would this stop fuel going through the pump? Or just building pressure in the rail??

Thanks again.

[Jim Archer]

The pressure in the rail is monitored, and should it fall below a certain level, the pump bypasses to prevent any major leakage of fuel in case the HP side has failed.

You have fuel at the filter? And filter is full?

Put a inline primer between the in-feed from the tank to the filter and purge the LP side, all being well it should then fire up in a couple of seconds.

PRV - simple check is to pull the leak-off return line from the 'rear' end of the fuel rail and see if fuel comes out of the spigot when cranking. More complicated version is to monitor rail pressure using diagnostic kit.

Jim

[Rossgal]

Hi,
Fuel is at the filter and full. Doesn't seem to be building any pressure at all. Is there a solenoid or something stops fuel going through the pump? I have no codes showing on diagnostics

Just seems very little fuel going through the pump when cranking. I am at my wits end!!!

Thanks for the help.

[Jim Archer]

The Suction Control Valve (SCV) - posh term for what is effectively the stop solenoid - controls pump output to the HP side, and thus rail pressure.

How do you know that there is very little fuel going through the pump? The only way to tell how much is passing through the pump is to put a flow meter in the pump return line back to the tank - once primed up, most of the fuel will bypass the HP side anyway until full delivery is required.

If you are cracking HP unions off, the PCM/pump/SCV instantly dumps/bypasses straight into the pump return back to the tank when it sees the rail pressure drop off.

Have you got Crank and Cam Position Sync? Again, the HP side won't pressurise if there is no injector demand/requirement. If the motor has been out, it's easy to forget the Crank sensor and/or damage the wiring. Diagnostic should see both senders, and confirm Sync.

Jim

[Rossgal]

Thanks Jim,

The crank and cam sensor show sync on diagnostic.
Someone had suggested cranking over drawing fuel through the pump and it fills up a bottle on the leak back side.

Does the PRV remain open and just let fuel through if it is faulty? Or does it need pressure to actually work?

I had cracked the pipe feeding the fuel rail and seems I get nothing or very little through it, surely it should pump out? Hence why I think maybe something is stopping it.

I think it must be something simple as the van ran fine before and I wouldn't have thought the pump would have just died since it was disconnected.

Thanks again for the help.

Stephen.

[Rossgal]

Ok, so an update on this.

SCV seems ok as had it out and it was going in and out freely with power on off.

Is there any way of testing the PRV?
I have no pressure in the fuel rail so is this the most likely cause? It doesnt leak fuel from it if I prime it up, fuel comes out the leak off pipes first.

Is the pump knackered? If I crank it over I don't seem to be building any pressure.? How can I check it?

Thanks for any help

[davyjcb]

The scv is NOT a solenoid it is a pwm valve it ossilates and that is how pump pressure is governed
The prv is always closed unless the pressure builds too high and only then does it open to protect the system
Cracking a fuel line when cranking will not allow fuel to pump, with the rail full of fuel pressure can build very quickly if the rail or any associated high pressure pipes are disconnected the pump won't even try to make pressure
The only way you are going to find out if the pump is working is to connect it to a suitable diagnostic interface and read the pressure from the rail

[Rossgal]

Hi thanks,
But as I've said before I have no pressure in the fuel rail, there are no diagnostic codes and I can only crank it over.

Does that mean if I turn the pump with a pipe off it will not pump anything? How do I check if the pump is actually pumping anything?

Would the scv stop the pump from allowing fuel to be primed through it? I have had it out and it was moving frwely under power. Is there no way to prime fuel through the pump to the fuel rail?

Thanks if you can answer any of these!!!

[davyjcb]

With a pipe open it will not try to generate any pressure or flow
As Jim says remove the return pipe from the prv and crank over,there should be no fuel leakage coming out of the rail your pump could be fine but the prv if leaking can drop the fuel pressure below the threshold that the pump must make in order for the engine to start

[v8dave]

Is there any way of testing the PRV?
I have no pressure in the fuel rail so is this the most likely cause? It doesnt leak fuel from it if I prime it up, fuel comes out the leak off pipes first.

There is a leak off pipe from the fuel pump, another from the prv and four from the injectors. They all connect together before the return line gets to the fuel filter.
If fuel comes out of the injector leak off ports when you prime it then it can only be getting there through the fuel pump and rail.
If it is coming out of the pipework it must be coming from the pump leak off if the injectors and prv are disconnected.

Have you cranked it with the prv leak off pipe disconnected?

The fuel rail and injection volumes are very small so very little fuel flow is needed to create lots of pressure.

You say the sync is good so you have diagnostics. What is the rpm when cranking? what is the fuel pressure?
Does the diagnostics offer a engine crank no start test, ford ids has this test.

On the transit the scv is open when unpowered, if it is unplugged you should get a fault code for it's control circuit and if the engine starts the fuel pressure will be too high.

Is the fuel pump turning when the engine is turned? Have a look in through the access cover on the timing cover.

[knobby1]

Have you tried cranking it with a sniff of easystart..?? If it runs on easystart you'll at least know it's capable of running. You mentioned your crank and cam are in sych so we can probably rule out a cam timing issue.

Lord Knobrot

[Rossgal]

Hi guys,

I have tried starting with the scv both connected and disconnected. No joy.
My next step will be to see if the pump is actually turning, what would stop it?
I have the inlet off at the moment but I will crank it over and get the rail pressure reading

I haven't tried using easy start
I will ad my findings later

Thanks again.

[Rossgal]

Ok, so another update.
After much head scratching and testing with made up pipe blanks it looks as though one of the injectors is allowing fuel to leak right through it.
With this injector blanked off got the engine to fire.
New injector on the shopping list.

Thanks for the help.