3tgte prolonged fuel problem?

[The GW]

OK im starting to get a little fed up with this problem so ive decided to post on tech to gather a few opinions and give me some new things to try.

My 3tgte in a ta22 (running a haltech E6, 440cc injectors, intercooled, battery relocated recently) has started to play up. Only just got it registered so havent driven it enough to determine any big trends however: I can drive it around and boost it ok for a while and it will have no problems - sometimes an hour, sometimes 20 minutes and then all of a sudden it will start idling really bad, develop no power and will eventually stall (within about 100 meters). At this stage it is really unhealthy when i try to rev it. When i try to start it, it wont kick in and if it does it back fires out the intake and sounds terrible - i gather this indicates a lack of fuel?

Now, everytime it does this, it has been around 3/4 of a petrol tank full(my guage is accurate). When i chuck some fuel in it (like 10 litres when i get stranded), it seems to pipe up and clear itself out and goes fine again - most of the time.

I have replaced both fuel pumps, im now using a VL turbo pump main and a big bosch pump as a pre pump. I have also had the pre pump mounted pretty low. Hasnt fixed the problem. When its been stranded i also chucked a spark plug in the lead and it seem to ark fine, so i gather the spark is good? my coils dont feel excessively hot. ive put new leads, plugs, fuel filters etc on the car, also done a road tune.

im thinking it may be a leak in the pickup hose, it may suck air when it is under 3/4s full or something like that? either that or a heat soak issue?

i dont know, it is frustrating...please guys give me a new list of stuff to check, if you need anymore details just ask
cheers, grant

[blacktop]

have you checked the fuel return, or it might not be venting. just a thought

[Duk]

What sought of air/fuel ratios are you running?

[oldcorollas]

can you hear any change in the fuel pump at those times? like getting louder (air leak ,blockage) or quieter (fuel reg not reg`ing) etc

[allencr]

I think a'fuel problem' is impossible to have at idle if you haven't had a problem at WOT in 3rd gear!

[TA22 GT]

You might have a faulty fuel pressure regulator. Its fitted to the rear of teh fuel rail and in stock form is set to 275kpa.

Put a temporary pressure gauge on the incoming line and check the pressure when it plays up, if it not maintaining around 275kpa then its either the pump, filter or regulator.

Hope this helps,
Simon

[The GW]

ok thanks very much guys ill try that all out. i havent given any thought to the regulator, good idea gt, ive put on new filters and replaced the fuel pumps and it still does it.

oldcorollas, ive only driven it once with the bosch pump as the prepump, so didnt give that enough attention, i will listen next time however. when the pre pump was just a facet pump it used to get very loud after spirited driving, it sounded like it was working hard, so i mounted it lower (still has the problem) then replaced it with the big bosch pump (which is high volume AND high pressure...) and the problem is still there.

not sure if it is worth noting, but when the car does idle ok, it runs REALLY rich - that is, it sprays large quantities of petrol out the exhaust when you rev it in neutral.

[The GW]

havent got an air/fuel guage in the car as yet

[Duk]

Sounds like the engine is flooding, fouling the plugs and leaving you with the pain in the arse you're suffering from .
Spraying actual fuel out of the exhaust is pretty dramatic . Even black smoke would indicate excess fuel. Can you at least adjust the accelerator pump settings to try and get a clean free rev?
Air/fuel ratio meters are essential when tuning, and are well priced these days. I have an Innovate AFR, got it new off e-bay for a very good price.
Best of luck.

[thechuckster]

gut feeling - you've disabled the breather from the tank to the charcoal cannister (or you dont have one) - as temps rise in the tank, it's pressurising and the fuel pump is having difficulty delivering the right pressure up the fuel rail.

I think earlier Celicas dont have the 3rd line from the tank which means you rely on the correct filler cap for equalising pressure in the tank.

Query: when removing cap to fill up fuel, does it release a lot of fumes/pressure? or does it suck in a whole lot of air?

Test - loosen fuel filler cap and see if problem goes away.

[The GW]

we have already given it a quick tune with the laptop and wideband sensor...still runs pretty rich though. i wouldve thought the backfiring out the intake would indicate lack of fuel plonka? it seems like that, because it actually did it about half an hour after we gave the haltech a comprehensive road tune.

chuckster - it definately makes a 'sss' noise when i release the cap, just tried to test it then, but couldnt tell if it was blowing or sucking. im assuming it blows a small amount of fumes out? atleast thats what it sounds like, but it doesnt seem overly excessive? next time it does it, i will loosen the cap for sure. your theory actually does seem pretty good, as when we put the 10 litres of fuel in it goes again (as we have opened the cap). Also, had the tank out and it never had this particular problem before then. Ill definately keep you posted. thanks.

another method im going to try if that doesnt work is undoing the bottom hose on the surge tank, and seeing how much petrol is in there. then ill be able to isolate if the problem is before or after the surge tank.

another thing i forgot to mention is that on a full tank about a week ago, i boosted around fine on and off for around an hour, car went fine, the only time it stuffed up was twice BRIEFLY as it surged when i cornered hard to the right.....

keep the suggestions coming guys its much appreciated!

[allencr]

it runs REALLY rich - that is, it sprays large
quantities of petrol out the exhaust when you rev it in neutral.

You DO NOT have this symptom/problem, because it is pretty much impossible, and has never happened to you or anyone else!

[The GW]

say what? allen the car is running rich at idle, it sprays black liquid on your hand which smells like petrol when you put your hand behind the muffler and someone revs it. also sprays it all over my garage floor. Dont get what your angle is there...

[thechuckster]

if it was petrol, you engine would be hydralicising (spell?)

it's more likely to be moisture in the zorst

[ONCE-NA]

Running ultra rich isn't going to be good for piston, bore, ring wear, washing the oil away...

Yeah like he said it would pedominatly be moisture comming from the exhaust, but running righ there would be an unburt fuel smell