Ian C Posted September 3, 2011 Share Posted September 3, 2011 I haven't driven my Supra much for aaaages, now I'm enjoying a renaissance However, I've found a new and fun thing it likes to do. It starts just fine when cold or after sitting for 10 minutes ish, but if the car is warm and I stop, then get back in after say filling up with fuel, it turns over and tries to catch but doesn't. Nice of it to only manifest when I'm in public places, for maximum embarassment At the moment I try and start, give up, put accelerator to the floor, try and start for a good few turns, give up, wait for the electrics to power off, try and start again. That seems to eventually get it going, but it's still embarassing. I believe this thing could be vapour lock, where the hot engine fills the fuel lines with petrol vapour instead of liquid? Is this plausible? Is there a fix? I don't think it's an overfuelling issue per se as I haven't changed the map for years and it didn't do it last year. Thoughts please -Ian Quote Link to comment Share on other sites More sharing options...
mellonman Posted September 3, 2011 Share Posted September 3, 2011 i had a problem like this with mine but i have a piggy back ecu, i chucked aload more fuel in at cranking rpm at a higher air preasure, Quote Link to comment Share on other sites More sharing options...
absz Posted September 3, 2011 Share Posted September 3, 2011 Start with checking the coolant sensor first (Resistance) will cause difficult starting on a hot engine as it floods the plugs Quote Link to comment Share on other sites More sharing options...
CanisLupus Posted September 3, 2011 Share Posted September 3, 2011 Had a similar thing. ECU ground was faulty Quote Link to comment Share on other sites More sharing options...
dandan Posted September 3, 2011 Share Posted September 3, 2011 What's your fuel pump and non return valve setup Ian? Quote Link to comment Share on other sites More sharing options...
Ian C Posted September 4, 2011 Author Share Posted September 4, 2011 Start with checking the coolant sensor first (Resistance) will cause difficult starting on a hot engine as it floods the plugs I can get the values off the E-Manage, although as it's fine otherwise and the AFRs are all normal, it's probably not that. Easy check though Had a similar thing. ECU ground was faulty Probably not that as it's only after a couple of minutes of standing with a fully warm engine. A dodgy ECU ground would cause all sorts of other problems under most conditions. What's your fuel pump and non return valve setup Ian? Walbro pump. The whole fuel system is nonstandard up to the metal return pipe in the engine bay, but that bit is stock going back to the fuel tank. I'm not sure if there is a non return valve apart from in the pump, I certainly didn't fit on The fuel pressure slowly drains off, perhaps I should check that. I'd have thought that the first attempt to start would repressurise the system though, that's what is supposed to happen. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted September 4, 2011 Share Posted September 4, 2011 Leaking injectors or a too slow a pump run time to repressurise the system at key on sound likely. Are you monitoring fuel pressures? A mechanical gauge that shows fuel rail pressure with the ignition off should show near running residual pressures at least half an hour after switching off. If not there's fuel leak externally, a leaking injectors(s) or a faulty none return valve in the fuel pump. You can power an electric guage bypassing the ignition switch to do these tests. Quote Link to comment Share on other sites More sharing options...
Ian C Posted September 4, 2011 Author Share Posted September 4, 2011 I have a mechanical pressure gauge on the FPR, I can look at that, see what the pressure is half an hour after keying off a fully warm engine Sounds like a good check but it'll have to wait until I'm not on shift on wednesday. I'll also check fuel pressure on the gauge when it's next having a strop. Quote Link to comment Share on other sites More sharing options...
bignum Posted September 4, 2011 Share Posted September 4, 2011 I had the same problem, turned out to be leaking injectors. Quote Link to comment Share on other sites More sharing options...
suprab Posted September 4, 2011 Share Posted September 4, 2011 what about the crank sensor Quote Link to comment Share on other sites More sharing options...
CanisLupus Posted September 4, 2011 Share Posted September 4, 2011 Probably not that as it's only after a couple of minutes of standing with a fully warm engine. A dodgy ECU ground would cause all sorts of other problems under most conditions. Thing is the car ran fairly normal under all other conditions as the ground was intact to a certain point. Found the mistake by checking the injector pulse with an osciloscope where i saw that the drop just wasn't enough to start when warm. It's unlikely to be your problem too but keep it in mind if the other possibilites aren't the cause Quote Link to comment Share on other sites More sharing options...
Stephendjb Posted September 4, 2011 Share Posted September 4, 2011 Mine is doing this as well. It's turned out the 9v phase of the fuel pump ecu isn't working properly. It'll start from hot but die immediately as the revs drop to tick over & fuel pressure reads zero. I'm going to be doing a modified version of the 12v mod on mine as a temporary fix (Using a relay for safety) until I can find an Aristo ecu as unfortunately it's different to the Supra one. Quote Link to comment Share on other sites More sharing options...
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