I ran the car very low on petrol yesterday, and filled up. Since then the car will drive OKish until roughly 3k revs then it cuts out like there's no fuel?

This happens revving in neutral also.


My guess is fuel pump, anyone had anything similar?

I took it for a 100 mile drive yesterday to see if it self rectified, but no such luck.

Car is a UK classic 99

 

You could have scraped all the crap from the bottom of the tank into your injectors

 

Injectors was my other fear, I'm going to sling a bottle of that injector cleaner in it shortly, worth a blast I guess.

 

Worth a shot

 

Your fuel filter should, um, filter any crap out long before it reaches the injectors. maybe your filter needs changing. Or could be your pump giving up?

 

I've just put a small bottle of fuel system/ injector cleaner in, and also changed over the filter.

Do fuel pumps tend to gradually fail, or is it an on/off with a pump.

 

Sound like all the crap has come up from the bottom .

 

No change as of yet guys.

Would the fuel pump be the first logical swop over?

 

Don't wast cash or u may be loaded so go for it . Take it to a Subaru place find out for sure . What year is it

 

U have done the filters yer

 

Really need ro check fuel pressure before investing in a pump. Could also be the fpr

 

Yer u may be right there . And if its a pump the y not upgrade it . Turn a negative Into a positive . Lol .
Let us all no what it is and what did you sort out in the end for it. Would like to no the out come . And if it happened to me I will no what to look for .

 

Fuel filters been changed yes, I was rather hoping to self diagnose this using advice from the forum. Usually works for me.

 

The pump should have a filter on it, but as its probably 15 years old and not been changed it might be worth doing for piece of mind anyway.
They do not like being run with no fuel.

 

What year is the car. As you ran it so low it may have gone into Limp home mode. You could disconnect the battery (if you have the radio code) overnight and see if this will get the ECU out of Limp home mode.

 

I've never head of this feature before on an impreza

It's a 99

 

Seems to be getting worse, I took it out just now and completely conked out. Exactly like running out of petrol.

Would not start, left it for 10 mins, managed to start and nurse it home.,

 

You should be able to diagnose fuel pump quite easily.

Firstly you should be able to hear it prime when you turn the ignition on as long as you do it within 30 secs of pressing key fob to disable immobiliser.

If it doesn't prime, then you can measure the resistance of the fuel pump at the connector under the back seat (2 bolts to remove the seat pad). If this is much more than 1 ohm its probably dead.

Immobilsers do fail on this era car - check that you are actually getting >12V at the connector when the pump should be priming (will most likely need a second pair of hands to turn the key...)

 

PS, my pump failed quite suddenly at about 165k miles last year, same age car. Car conked out randomly one day and restarted 5 mins later. Then ran fine but a few weeks later failed to start at all and pump was completely dead.

 

It's weird though, if I gradually and gently rev it it will redline, as soon as you pu your foot down more than a few cm it cuts.

I did fill up with BP ultimate, as that's all I could chance getting to. Surely this couldn't be the cause could it? I've just whacked a bottle of octane booster in it but no difference.

Hopefully my replacement pump will be here tomorrow so I can rule that out.

 

You don't need much fuel to get up to red line in neutral if you are gentle with the throttle.

If it is starting to fail but not dead, and cannot maintain required pressure, light throttle might be ok, because ECU will adjust fuelling because of lambda sensor, but at wider throttle it can't supply enough fuel and will just stumble or cut out.

 

Makes sense, I always thought that when a pump failed it just stopped altogether, I didn't realise they. Oils gradually fail.

Fingers crossed it is the pump.

 

Pumps been swopped out for a WRX unit that my mate had lying around, running exactly the same....

Any other ideas on what I could look at guys?

 

Was there a filter on both pumps?
What was the condition of the wiring, and have you tested the voltage at the pump?

 

Yeah, both pumps had the bag filter, no voltage been tested, but if can hear them whirring one cars running so does voltage need to be tested?

 

That old chestnut, it's utter bollocks. Point at which the fuel pump draws fuel from the tank will be about as low as it can possibly be, just where all the supposed "crap" may have accumulated after you've left your card standing for a while.

For starters most of the petrol bought of the average UK forecourt is pretty clean and if you've ever seen the inside of a petrol tank you'll know that there is little or no "crap" in there.

Just another urban motoring myth.

 

Those saying all the crap at the bottom... have you ever seen inside your tank? I have on multiple cars, and they all looked super clean to me!

 

Good to know, any ideas then what it might be?

 

yes , you have sucked loads of crap from the bottom of the tank

 

I guess you are not getting any engine management light on the dash?

Have you checked the fault codes just incase? (http://www.scoobypedia.co.uk/index.p...eadingECUCodes)

You could try changing the fuel filter, but it would take a lot of "crap" to almost completely block the filter.

If fault codes give no clues, I would check you have a decent spark and plugs are good. If you can spend a tenner on a VAG-COM USB cable and have a laptop then you can monitor readings from all the ECU sensors which is very helpful debugging things like this.