And then you **** yourself big time, and start looking for all sorts of excuses as to why it happened

[Edited by Dave T-S - 11/6/2002 8:23:49 PM]

 

Please don't start a fight/debate or I'll report this thread to the mods!

I just want to know why fuel surge is called what it is because if you look up the word 'surge' in a thesaurus it says stuff such as 'flow' and 'rush forward' My understanding of the word is that if you said, 'there was a surge in water levels' it would mean there was a sudden 'increase'

My experiences of this problem have involved the engine pretty much stalling because of an apparent lack of fuel and I can't see how an increase in fuel would cause a problem. Its no doubt my lack of grasp of English but I thought I'd ask just to be sure I wasn't missing something

 

Ever considered that it might be surging AWAY from the fuel pick-up?

 

yep basically the fuel surges to one side of the tank, you experience the effects of fuel surge if the line is on the other side.

 

Jesus squizz I was only asking Thanks for clarifying Jay m A

 

I think the techinal term is feul starvation but then again i may be wrong.

Mel.

 

Sorry should read Fuel not Feul just cant seem to edit my post.


Mel.

 

The word starvation would seem a lot more acurate to me.

 

The engine suffers fuel starvation due to a fuel surge away from the fuel pickup in the tank

 

A stated previously it is the surging of fuel in the tank to one side which causes a starvation at the fuel pump pick up point.
An Impreza fuel pick up is on the drivers side of a wide fuel tank which straddles the propshaft.
When you corner to the right the fuel 'surges' to the left side of the tank, the fuel pump draws in air and the fuel pressure to the engine drops causing the power to cut instantly.
The effect is actually worse than just lifting off the throttle. If the throttle is open then the engine braking is greater due to the pumping losses.

Andy

 

DTS ouch

 

FB
Had to

 

"Please don't start a fight/debate or I'll report this thread to the mods"

Nobber

 

And the award for most contructive post of the day goes to.......MRK IV

 

Exactly as Andy says but you can also get it under hard straight line acceleration when at low fuel levels. The fuel in the tank surges to the rear away from the pump pick up causing a temporary loss in acceleration. There is no danger of stalling unless the clutch is depressed but even then fuel flow is restored as soon as the cornering force or acceleration reduce.

 

I thought there were baffles within the tank to prevent this?

Also: When I had the GTIR I fitted a resevoir just before the fuel pump to prevent this. Dunno if you can do the same on the scoobies?

 

I still don't understand why you'd get this on a long sweeping bend though.

I've only ever had this sort of problem pulling away sharply or going around a roundabout whilst running on (literally) vapours (i.e. praying that I can make it to the petrol station with 2 litres of fuel left).

In 3.5yrs of Scoob ownership, I've never had this at any other time, including fast driving with low fuel levels (i.e. warning light on).

Only times I've heard folk complaining is hard-rights, quick launches, hairpins after heaving braking (i.e. Knockhill). In fact, those who mentioned getting this at Knockhill haven't said they got it at any other corner other than the hairpin.

Stefan

 

The reason many people have not experienced this on corners is because it is most likely to occur when you are on the power fairly hard ie needing lots of fuel flow and pressure. Knockhill hairpin is the type of corner you turn in then give it plenty to get round the uphill corner !
The inlet filter to the fuel pump also acts as a sort of reservoir, it absorbes probably a few seconds worth of fuel. This is why you don't always get the 'surge' effect instantly ie you may be able to accelerate hard in 1st then it bogs in second as the air gets through to the pump.

Andy

 

The bend Saxo mentions is a turn in - power on type of bend.

 

K/hill hairpin is the only place I got it too, except when I had one of the early Walbro uprated fuel pumps when we did not know to use the original pickup which is longer.

And it isn't really THAT unsettling to the car it just dies like a slow version of fuel cut. I'm not too worried about it becuase if you have a high enough lateral g like the knockhill hairpin you are not flat out around it, it is when you floor it onto the straight that it happens after a second or two. It has that slow dying swan oh **** my engine has blown, but then it comes back and you carry on chasing whatever you were chasing (or in my case accelerate away from the driver behind who caught me in the corner but hasn't enough power to pass on the straight - well some of them like Andy F and those Mitsoobi$hi things )

 

The effect varies from car to car, I would expect your scoob would initially go faster with fuel surge John as it leans out to the 'sweet' zone

 

Andy, is your 0-100 time up hill?

John, I would have thought no one could catch you on the corners with those AP brakes

Stefan

 

Km/hr

 

Andy mine is already in MY sweet zone thanks very much LOL.

I was logging yesterday and had an 830 mV lambda reading on full load and thought of you and smiled The lambda sensor was hot though. Will be using the wideband to get it right with the 550s and induction kit which both mess it all up a bit.

 

I get surge all too easily I think? I'm surprised by the number of people that have never had it?? Hmmmm? Maybe I'm just particularly brutal!

The difference with the knockhill hairpin is by the time your likely to get surge the speed must be pretty low (sorry don't know KH that well but I'd guess maybe 40mph) At the time I got it I was doing twice that which is maybe why the effects were so much more severe?