Hi all,

I have a Punto that was having issues restarting when warm etc so changed the crank sensor - this fixed the problem.

I now have a new problem. The car won't stay started! It starts everytime but then stalls after 4/5 seconds. The problem first started when I filled up with diesel (definitely diesel) and since then it dies everytime.

I've done a search but most problems are that the car cranks but doesn't actually start. That's why I'm confused with mine as it does actually start but then just dies. :bang:

Got too dark tonight but I'm going to check the fuel filter for dirt although it is only 2 months old.

Anything else I should check on a car that is starting but not staying started?!!

Cheers

Any engine management light/fault code?

id be checking the glowplugs might noy be getting hot enough for starting so it stalls

but it could be a poor connection on crank

ziggy

try turning the ignition on then iff then on again off then on

basically the plugs get 3x heating sessions to aid starting a simple test

ziggy

No engine management light or fault codes.

Tried the ignition 3 times - it started but again just stalled straight away.

It's almost like it's run out of fuel but the tank is completely full. It had been pretty empty (38 litres went in and I believe it's a 40 litre tank?) so I'm wondering if there's a blockage somewhere which is giving the engine enough fuel to start but not enough to keep running.

sounds like a fuel delivery problem

whenbu switch it on do u hear it prime up?

Ziggy

Yes I can hear the pump behind me every time I turn the ignition on.

I'm going to examine the pump tonight and also the fuel filter.

Is there a way of checking the high pressure fuel pump and that the fuel is getting through it?

your car has two fuel pumps, the electronic lift pump in the fuel tank, which will be the one you can hear when you start the car.

the other is a mechanical high pressure pump,

I suspect whats happened is the high pressure pump has failed and as such is not able to deliver enough fuel to keep the engine running however the electric pump is priming the mechanical pump with enough fuel to get it started for a second or two.

while you are there check the air filter and induction hoses as its possible to have a hose delaminate and bloke the air into the engine (this is probably unlikely)

i agree it does sound like a knackered fuel pump but not the one you can hear when you turn the keys

That would make sense.

Is there a way of checking the HP fuel pump? As you've said it's not the one you can hear when the ignition turns on so is there any other way of testing this pump.

It looks a bit fiddly to get to as well - anyone have experience changing one?

Becareful
diesels run mega stupid pressure - Okay the pump "MIGHT" be dead and there is little pressure

but if its upto pressure and its an injector issue that fuel in the pipe will be under a lot of pressure - enough to say Bye bye hand/fingers

Caution should be taken

ziggy

:yeahthat:
Far more likely the lp pump/filter is the problem so I would say stay away from the hp stuff for a while. There is a way to check out the lp side.You didn't hear this from me and I never did it but if you rig up a supply to the hp pump like an iv drip hanging up somewhere convenient it is generally enough pressure for the hp pump and if it then starts you have your problem.
When you say this first started after filling with diesel , was this an unusual event?
Just noticed from your previous post you were having power loss at high revs. This can be a symptom of filter blockage or lp pump failure. Once the car starts the lp pump is not really needed to keep it running and is only required when the hp needs a lift at high consumption.

Not unusual that it was at the petrol station - I just found it bizarre that the car was fine driving there and since then this problem has meant I can't go anywhere.

If the car starts every time, doesn't that rule out the LP side completely anyway? That's obviously doing it's job in starting the car, it's once it's started that it dies.

Forgot to update my power loss thread - that was due to a hose sheering off on the overboost valve. Refitted with a brand new jubilee clip and that problem was gone immediately.

I also had the well known not starting when warm issue so replaced the crank sensor and that was sorted.

I don't think this issue is related as both previous problems were a few months ago and I've done a few thousand miles since then. Could be wrong though.

Tonight I removed the fuel filter and had a peek in - it was only replaced in July so I think it's fine. It was full of diesel.

I also checked all fuses and they are fine.

The battery however was missing it's green light so that is now charging in the kitchen - could this be the problem? Is the HP fuel pump reliant on a fully charged battery?

garysmith21 said:

The battery however was missing it's green light so that is now charging in the kitchen - could this be the problem? Is the HP fuel pump reliant on a fully charged battery?

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Nope it's mechanically driven off the end of the cam shaft, also the 'green light' is just a hydrometer, a float that will only float if the electrolyte in the battery is a predetermined specific gravity it is fairly irrelevant you could charge it for 10 hours and find you still don't see it but the battery is fine and fully charged

AndyRKett said:

Nope it's mechanically driven off the end of the cam shaft, also the 'green light' is just a hydrometer, a float that will only float if the electrolyte in the battery is a predetermined specific gravity it is fairly irrelevant you could charge it for 10 hours and find you still don't see it but the battery is fine and fully charged

Click to expand...

Thanks - I can rule that out then!

Too much of a coincidence that this happened after filling an empty tank. Starting from the top you would have to suspect the fuel itself or the filter is blocked. Diesel tanks have sludge in the bottom and if you run very low it gets sucked into the filter blocking it very quick. The filter can appear full of clean fuel but actually be blocked. Change the filter or run a separate supply to the hp pump preferably with fresh fuel.

Only just seen your reply so not tried your ideas yet.

What I have done is reconnect the fully charged battery - knowing this won't make a difference.

And removed the filter and filter housing, inspected it as much as possible and not seeing anything untoward reconnected it.

Turned the ignition 3 times and heard lots of gurgling as the filter filled back up. Turned the key and started perfectly and revved normally for a few seconds. And then died again...

garysmith21 said:

Only just seen your reply so not tried your ideas yet.

What I have done is reconnect the fully charged battery - knowing this won't make a difference.

And removed the filter and filter housing, inspected it as much as possible and not seeing anything untoward reconnected it.

Turned the ignition 3 times and heard lots of gurgling as the filter filled back up. Turned the key and started perfectly and revved normally for a few seconds. And then died again...

Click to expand...

The 3 key turns was to eliminate the glowplugs not heating sufficiently - however its not bad practice todo when its freezing cold outside

Have you checked the crank sensors plug - clean tight and secure?

I think there is a fueling issue here, enough pressure to feed injectors on prime, but not enough to keep it running.....

Ziggy

Going to try the 'IV drip' tonight! Any tips on how to do this? I'm assuming there'll need to be an airtight seal so would lodging the end of a funnel in the fuel line work? Or even dunking it into a jerry can?!

And I'm also assuming gravity will need to play it's part in supplying some pressure?

Thanks all for your continued help!

Both will work. Just remember it has to be spotlessly clean and secure it well. Look a right fool starting a fire.
And yes about a foot or two of gravity keeps it sucking diesel.
When you disconnect the lp supply you can switch on and direct it into a bucket. There should be a good spurt of fuel. The lp pumps are generally 1.5 - 2 bar. if there is only a dribble then the problem is the pump itself , the filter or some hose somewhere is perished and or blocked.

Don't forget that when you go to crank the lp pump will deliver something so might be a good idea to pull the fuse on the fuel pump before you're ankle deep in fuel.