Fuel starve problem

HI guys,

So I have had an intermitent issue whereby the car would be running fine (mkiv gte to single conversion auto) and then start to run rough, similar to how a misfiring engine would sound, however as soon as it happens the afrs jump straight to the max at 17-1 upwards, so is leaning out horrendously...this happend for about 10 seconds until it sorted it self out...I then drove it a couple of times and it was fine...however it started doing It again on start up and wouldn't stop, I suspected a blocked fuel filter so changed it, it was then fine for about 4 miles and then then started doing it again, but would cut in and out of normal running and what I think is fuel starving (the pump is new)...

The car on the whole is very reliable and this is the first running issue is have had with it for about 2 years...when it first started doing it I had about 2 bars of fuel and then did it again after a fuel fill up and was about 1 or 2 bars from the bottom, however I have run the car in the past way lower on fuel supply and never reacted like this, and nothing has changed in the way of fueling.

It has stopped doing it now, but don't want to be out far away if it does it again...just wanted to know people's guesses to what it could be...and please don't just say the tanks empty hahaha.

Cheers in advance

check the wiring to the pump and the condition of the pipes from the pump in the tank

Pumps are cheap enough perhaps just replace it?

Do you have any fuel pressure logging on your ecu?

Yea, I don't mind changing the pump again, just don't want to replace loads of things in succession to find out that it's something else, as I have changed most of the parts on it for new replacements anyway and all has worked well till now...and no I don't have pressure login on the ecu

Jist wanted to see if anyone would jump out saying that they have either had the issue before and know what it is, or if anyone knows straight off the bat what it could be

Get the map checked? Pull the logs?

AFR's going lean does NOT necessarily mean fuel starvation, a bad misfire with un burnt fuel can also show lean, so don;t discount the ignition. In fact I personally would be looking at plugs and coil packs and their wiring first.

I had similar symptoms on my car and after changing a whole load of things, it turned out to be a failing Bosch fuel pump.

Changed it for a high flow Walbro and all was good again.

I had similar symptoms on my car and after changing a whole load of things, it turned out to be a failing Bosch fuel pump.

 

Changed it for a high flow Walbro and all was good again.

Hi,

Yea I have a walbro 255lph pump in there at the moment and is undef a year old

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AFR's going lean does NOT necessarily mean fuel starvation, a bad misfire with un burnt fuel can also show lean, so don;t discount the ignition. In fact I personally would be looking at plugs and coil packs and their wiring first.

Is what I wanted to hear to be honest haha, as I don't fancy going to buy a new set of injectors, wiring or a new pump when all of it is fairly new...will checking the plugs and packs first off

AFR's going lean does NOT necessarily mean fuel starvation, a bad misfire with un burnt fuel can also show lean, so don;t discount the ignition. In fact I personally would be looking at plugs and coil packs and their wiring first.

Is what I wanted to hear to be honest haha, as I don't fancy going to buy a new set of injectors, wiring or a new pump when all of it is fairly new...will checking the plugs and packs first off

So I have changed the pump, changed the filter and it still does the bad leaning out...

It starts and drives perfectly, but once you turn it off and don't leave it over night upon start up to will run lean and very lumpy, on the as we are looking at 16 to 1... after a few minutes it usually sorts itself out, but not always.

What else can it be? Does it sound like the reg?

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So I have changed the pump, changed the filter and it still does the bad leaning out...

It starts and drives perfectly, but once you turn it off and don't leave it over night upon start up to will run lean and very lumpy, on the as we are looking at 16 to 1... after a few minutes it usually sorts itself out, but not always.

What else can it be? Does it sound like the reg?

What does the fuel pressure look like pre start up (does the rail hold pressure on turn off), and on start up?

What does the fuel pressure look like pre start up (does the rail hold pressure on turn off), and on start up?

I am not sure as it is a stock rail and stock reg, however it is single converted and tuned, but been running well for the past year...

On start up its the same as it always has been, is only ever once it's been driven and turned off and turned on again...before I changed the pump it was doing it all the time, but now just after it has been driven.

Best guess is fuel vaporisation in the rail or elsewhere because the one way valve in the pump is faulty. the system SHOULD hold near idle pressure on engine shut off for a LONG time. A leak would cause it, but you'd see or smell fuel. I would make an adapter to fit a gauge on the fuel filter or on the top of the fuel pump plate in the boot and monitor fule pressure if i were trying to fix it. Second best guess is a faulty engine ecu water temp sender or air temp sender. What ecu is it and has it got data logging capability?

Best guess is fuel vaporisation in the rail or elsewhere because the one way valve in the pump is faulty. the system SHOULD hold near idle pressure on engine shut off for a LONG time. A leak would cause it, but you'd see or smell fuel. I would make an adapter to fit a gauge on the fuel filter or on the top of the fuel pump plate in the boot and monitor fule pressure if i were trying to fix it. Second best guess is a faulty engine ecu water temp sender or air temp sender. What ecu is it and has it got data logging capability?

The pump has been changed for a new one and is still proceeding to have the same symptoms, so would that rule it out?

Could it be the fuel pressure regulator? Or would it do it all the time if it was that?

I can't see or smell fuel, so don't think it's leaking.

It's only a piggyback greddy emanage as it's only running just under 500 at the crank, the setup is very simple sith the stock plenum, rail etc...so the ecu doesn't have data logging unfortunately.

It has a walbro 255lph pump

Sard side feed 800cc injectors

Other than that and the emanage piggyback that's the fuel system I am running with.

With the pressure gauge, as the system is braided line, should I make up an adaptor to fit before the filter? If so that should be ok, just not sure where the buy the gauge on its own that won't piss fuel everywhere haha.

Thanks again