JamieP Posted May 16, 2011 Author Share Posted May 16, 2011 Fuel pressure sensor is wired to the ecu now, any drop in pressure and the ecu will go into safe mode. We have a few ideas to try now and I will report back, first off fitting a new filter inside the big in line filter under the car, also the braided fuel lines are covered in a protective plastic shield that won't be helping we think, so going to remove that, also going to change the pump setup so just the one pump is running for off boost driving, and lastly Lee is going to fit a bigger return line as the one on it now may be restricting flow when at idle. Quote Link to comment Share on other sites More sharing options...
Ian C Posted May 16, 2011 Share Posted May 16, 2011 Fuel pressure sensor is wired to the ecu now, any drop in pressure and the ecu will go into safe mode. Have you got some trick logic going on to recognise that the fuel pressure fluctuates with boost/vacuum? Otherwise it'll trip as soon as you start the car We have a few ideas to try now and I will report back, first off fitting a new filter inside the big in line filter under the car, also the braided fuel lines are covered in a protective plastic shield that won't be helping we think, so going to remove that, also going to change the pump setup so just the one pump is running for off boost driving, and lastly Lee is going to fit a bigger return line as the one on it now may be restricting flow when at idle. You could check the temperature of the braided hose using a simple thermometer or thermistor multimeter and see how warmer it is than ambient - that'll tell you if the plastic shield is insulating it. I imagine the rubber hose is a much bigger insulation factor and I wouldn't like to see a protective shield removed for no reason, especially on your car I think your most effective move by an order of magnitude will be running just one pump most of the time. It's the act of "compressing" the fuel to pump it/increase pressure that heats it up, conduction from the ambient temps of the pump etc would be minimal. Quote Link to comment Share on other sites More sharing options...
JamieP Posted May 16, 2011 Author Share Posted May 16, 2011 You would have to ask Ryan about that one Ian, all i know is the fuel pressure sensor is wired to the ecu, any fuel pressure problems the ecu should look after the engine is what i have been told. Quote Link to comment Share on other sites More sharing options...
Ian C Posted May 16, 2011 Share Posted May 16, 2011 You would have to ask Ryan about that one Ian, all i know is the fuel pressure sensor is wired to the ecu, any fuel pressure problems the ecu should look after the engine is what i have been told. Ah, of course. Knowing him it'll make the tea and give you a massage as well Quote Link to comment Share on other sites More sharing options...
jagman Posted May 17, 2011 Share Posted May 17, 2011 How difficult would a control circuit be to shut the pumps down if line pressure dropped due to a rupture anywhere except the return line, yet still allow starting if line pressure was zero due to maintenance work? You can use the low oil pressure switch as an engine running logic to supply a relay and also fit a fuel low pressure switch again to the relay . The relay then removes power to the fuel pumps . Ie engine running (oil pressure) and fuel leak (low pressure) the pumps are switched off Quote Link to comment Share on other sites More sharing options...
Guest jaredb-123 Posted May 19, 2011 Share Posted May 19, 2011 Have you changed the filter ? if so have you notice a change in pitch of the pumps ? Quote Link to comment Share on other sites More sharing options...
JamieP Posted May 19, 2011 Author Share Posted May 19, 2011 Not touched it yet, going into SRD in a couple weeks. Quote Link to comment Share on other sites More sharing options...
Ricky49 Posted May 21, 2011 Share Posted May 21, 2011 Just to report on my fuel issue. I'm still having problems. After fitting the new pumps and also having the protective plastic removed after about 1.5 hours of driving my AFR's slowly creep to lean and then off the scale. Today I really struggled to get the car home and it sounded like it wanted to cut out. After speaking to one of Lee P friends he seems to think it could be the fuel injector heating the fuel up as it pass through the last bit of the injector. As he said if the injector is hot and the fuel is getting forced through a small hole and there would be a small amount of it it wouldn't take long for it to heat up. Next on the SRD check list is to fit a fuel temp gauge to see what temps we get when it starts to go wrong and maybe swap the injectors and see what happens then. I'm getting a bit down with this but we have to do these little changes to try and nail the problem. Quote Link to comment Share on other sites More sharing options...
JamieP Posted May 21, 2011 Author Share Posted May 21, 2011 Im not buying the hot injector idea as that would happen as soon as the car is up to temp if that was the case. Im surprised you are having this issue with twin walbros, my old twin walbro setup was fine, looking forward to seeing what your fuel temps do when you get the gauge fitted. Quote Link to comment Share on other sites More sharing options...
Ricky49 Posted May 21, 2011 Share Posted May 21, 2011 I know that's what I said to Lee you were running a similar setup and similar power to me when you were 730hp with no issues. But Lee's mate was saying that high imp injectors run hotter that the low imp and that's what lee's car run's other than that we have the same fuel setup. Quote Link to comment Share on other sites More sharing options...
JamieP Posted May 21, 2011 Author Share Posted May 21, 2011 when i was 730bhp i was single 044, 894bhp was twin walbro and high imp injectors with no issue, now twin 044 im having problems, its not an injector issue im sure. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 21, 2011 Share Posted May 21, 2011 How hot does the tank feel? The fuel would have to be damned hot to have a noticeable effect on AFR, or on 944 performance. Maybe the injectors themselves are getting hot and having issues, what make are they? Once you get over 800 cc I prefer to run staged injection, with two sets of lower flow injectors, only adding the second stage when needed. More complication, but hey, when was 730 BHP from a six pot 3 litre ever easy? Quote Link to comment Share on other sites More sharing options...
Ricky49 Posted May 21, 2011 Share Posted May 21, 2011 Well what ever it is it's testing my patience. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 21, 2011 Share Posted May 21, 2011 You aren't running the wiring to the 2 pumps through the stock connector on the tank top are you? It won't like that at all.... Quote Link to comment Share on other sites More sharing options...
Ricky49 Posted May 21, 2011 Share Posted May 21, 2011 You aren't running the wiring to the 2 pumps through the stock connector on the tank top are you? It won't like that at all.... Er I don't know to be honest Chris Lee would be the best person to ask. I felt the fuel lines, rail and filter and it wasn't too hot Lee also said it was not as hot as he thought it would be. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 21, 2011 Share Posted May 21, 2011 Even a single 044's current draw can overheat the terminals in the tank top stock plug and socket, and melt the plastic. Two would definitely be too much draw for them, they could well start to get mad hot and go high resistance after some time. I use proper sealed wire run through pedestals in an alloy top hat I turn. The feed throughs are available from ATL and from Demon Tweeks. ATL also do a proper multi pin plug and socket for tank usage, but it's mega money, and I am not sure what *its* terminals are rated at. Quote Link to comment Share on other sites More sharing options...
Ricky49 Posted May 21, 2011 Share Posted May 21, 2011 Would that apply to twin Walbros aswell Chris or twin Bosch's. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 21, 2011 Share Posted May 21, 2011 I wouldn't think the stock plug and socket would like twin anythings, to be honest, the pins are tiny. Have you got a fuel pressure gauge? With your mods I would use one, even if it's just for a short while until everything is tickety-boo. I prefer mechanical ones, but some people don't like high pressure fuel lines in the car. You can buy isolators for such fuel gauge hoses from Raceparts. http://content.yudu.com/Library/A1jzmx/2010RacepartsCatalog/resources/index.htm?referrerUrl=http%3A%2F%2Fwww.raceparts.co.uk%2Findex.asp pages 8/ 9 The feed throughs were in the Tweeks catalogue with the race fuel tank stuff. Quote Link to comment Share on other sites More sharing options...
Ricky49 Posted May 21, 2011 Share Posted May 21, 2011 I have a fuel pressure gauge and all the pressures are fine even when it goes tits up. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 21, 2011 Share Posted May 21, 2011 What do the AFR's do, change suddenly, or change slowly? From what you say re the fuel pressure it won't be a pump issue. Maybe injectors, maybe a sensor issue of some kind. I don't know what ecu it has, can you do some data logging? Is it running closed or open loop? Quote Link to comment Share on other sites More sharing options...
Ricky49 Posted May 21, 2011 Share Posted May 21, 2011 It has the syvecs and it has been back to ryan who has seen first hand the problem he diagnosed a faulty pump which I then changed both walbros for new ones. For about 1-1.5 hours of driving it's as it should be then you can watch the AFR drop to 17's then off the scale in 6th doing about 50mph it will be in the 16's then as you drive for longer it gets worse when eventually the car becomes undrivable like it doesn't want to run. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 21, 2011 Share Posted May 21, 2011 You need to data log some things. If it were my car I'd log AFR's, injector duty, fuel pressure, % closed loop correction (if it runs closed loop), TPS position, and engine coolant sensor and IAT sensor outputs. It's not using a fuel temp correction, is it? Quote Link to comment Share on other sites More sharing options...
Ricky49 Posted May 21, 2011 Share Posted May 21, 2011 Yes I think it is but I could say how much. Quote Link to comment Share on other sites More sharing options...
JamieP Posted May 21, 2011 Author Share Posted May 21, 2011 You need to data log some things. If it were my car I'd log AFR's, injector duty, fuel pressure, % closed loop correction (if it runs closed loop), TPS position, and engine coolant sensor and IAT sensor outputs. It's not using a fuel temp correction, is it? I agree, but all this is not a job for the average punter, i could be wrong here but reading between the lines the car went to Ryan for fault finding and he diagnosed it as a faulty pump, i presume he diagnosed this because the car was losing fuel pressure, (is that the case rick?) im now wondering if this could be an fpr issue, ive read of aeromotive fpr's having issues on supraforums, what fpr unit do you have Rick? Quote Link to comment Share on other sites More sharing options...
dandan Posted May 21, 2011 Share Posted May 21, 2011 .....what fpr unit do you have Rick? And where/how is it mounted? I think the chat on SF was related to excess heat affecting the regulator - presumably the spring? Quote Link to comment Share on other sites More sharing options...
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