leelbuk Posted February 22, 2011 Share Posted February 22, 2011 Does anyone here use a 044 with the standard check valve fitted and know roughly how long you sustain residual fuel pressure for? How important is it that this is retained? (May have bearing on my predicament) I have just finished putting together my single and have an issue with starting it and running it. If I fit the injectors and start the car the engine fires instantly and runs, but after it warms up a little and I stop the engine it won't start again at all and doesn't seem to ever want to start again (have left overnight to cool in case it was related to warm start on the map etc). It has only then started again once I have removed and refitted the injectors whilst I have been troubleshooting. As I wasn't confident in the injectors CW kindly flow tested the injectors for me but they are fine (one needed cleaning). I have re-fitted them and the engine fired up but yet again after warming up the car would run progressively worse and not start again. I then wasn't confident about the injectors sealing in the rail properly so I partially removed the rail and pressurised the system and could spot no leaks but noticed my residual fuel pressure would still drop to 0psi after only 5 or 6 seconds. I then started to clamp off various parts of the system and narrowed it down to the check valve on the fuel pump - If I prime the system and then clamp off the pipe between the check valve and the pipe at the top of the hanger then I retain my static fuel pressure (43psi) for 10/20 mins no problem so the rail, injectors, regulator and all connections should be leak free. How likely is this to cause problems? Could this be a symptom of vapour lock? Only reason I ask is that I'm a complete novice at this and rely on reading up on this. After doing some reading I have read about problems such as vapour lock being caused by lack of residual fuel pressure and wondering if this could be affecting me. So far it is the only thing that can explain to me why my engine will run for 5-10 mins and then refuse to start again after this when I haven't changed anything. Only thing I can think about doing now is replacing the check valve and putting everything back together. If this doesn't work I am completely stumped as to what is causing this. If anyone can advise me I'd appreciate it. I'm absolutely itching to drive this! Quote Link to comment Share on other sites More sharing options...
Wez Posted February 22, 2011 Share Posted February 22, 2011 Myself and a few others with the 044 pump removed the check valve and just fitted a fuel line straight to the pump, I always let my pump prime before starting. I have no idea how long the system maintains pressure. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 22, 2011 Share Posted February 22, 2011 My Skyline has a stock 044 pump and check valve. It usually holds rail pressure fore at least 1/2 an hour, sometimes more. Quote Link to comment Share on other sites More sharing options...
leelbuk Posted February 22, 2011 Author Share Posted February 22, 2011 Thanks for the reply Wez - seems like a wild goose chase then if you can run fine without however if my residual pressure drops within 5 or 6 seconds of priming then the injectors might not be able to fire much fuel into the engine? At this rate it might be easier to get a new rail and some tops feeds as I can't get my head around this problem. Since the car was running before all I have changed fuel wise i the pump and injectors so it will most likely be one of the two. Quote Link to comment Share on other sites More sharing options...
leelbuk Posted February 22, 2011 Author Share Posted February 22, 2011 My Skyline has a stock 044 pump and check valve. It usually holds rail pressure fore at least 1/2 an hour, sometimes more. Thanks Chris, is this the one with the banjo fitting that comes out 90 degrees? My check valve definitely seems dodgy so could be worth changing. Anyone know where I can purchase another? This is what mine looks like at the moment: Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 23, 2011 Share Posted February 23, 2011 Most Bosch pumps have a similar valve, see if you can find a scrap one, I threw a few out last month, sorry... Quote Link to comment Share on other sites More sharing options...
leelbuk Posted February 23, 2011 Author Share Posted February 23, 2011 Do the walbros have a check valve? Only reason I ask is that I didn't have the problem before and if the walbro has no check valve then I should be forgetting this check valve business and focusing elsewhere. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted February 23, 2011 Share Posted February 23, 2011 They will have but internal to the pump. The Bosch one can be blown out if you unscrew it from the pump body, it's only a spring and a valve and seat. Quote Link to comment Share on other sites More sharing options...
leelbuk Posted February 23, 2011 Author Share Posted February 23, 2011 Just took mine apart and it seems it's not a check valve at all and the restriction in the pump is causing the residual pressure to drop slowly rather than instantly - just ordered a valve from Burton power so hopefully that should stop this and I can test again. If it's not this then I can only think of putting my 550cc injectors & resistor pack back on and testing againwhich would put the entire system back to how it was apart from the fuel pump itself. Quote Link to comment Share on other sites More sharing options...
bignum Posted February 23, 2011 Share Posted February 23, 2011 A few questions for you, as i doubt it`ll be vapour lock, i had problems with hot start and it turned out to be my injectors weeping when sat full of fuel 1. are the injectors new, 2.what make are the injectors, 3. what ecu are you using, 4.have you had a look at the map yet. Quote Link to comment Share on other sites More sharing options...
leelbuk Posted February 23, 2011 Author Share Posted February 23, 2011 Hi Bignum, happy to answer especially if it helps keep me on the right path! I'm only buying the check valve to rule out the possibility of residual pressure being the cause as I really have no idea what else to think. I agree that vapour lock is unlikely as I've read it is uncommon in cars like the Supra but it is the only problem I have read about with similar symptoms. I'm happy to explore other possibilities that have similar symptoms if anyone knows any 1. are the injectors new, - No. 2nd hand from a member but had very little mileage on them due to the car being written off. Chris Wilson checked them for me and found that 1 injector had a slightly poor spray pattern but an extra clean sorted this. I have pulled the rail from the head and pressurised the system with fuel and nothing leaks from the injector nozzles or the rail and if I clamp off the fuel feed pipe (near the J-pipe/pulsation dampener) the rail will hold static pressure for 10-20mins easy. 2.what make are the injectors SARD 850cc High Imp side feeds - same as Blitz 850 side feeds and require a collar to fit stock rail. When I checked rail for leaks first time I found the lower o-rings weren't quite large enough to seal very well (would leak under pressure if injector was disturbed) so replaced with larger o-rings and now it totally seals even if injector is twisted in the rail whilst rail is pressurised. 3. what ecu are you using AEM EMS v1 4.have you had a look at the map yet I had Ryan round to do my startup map when the problem became apparent and it is supposedly setup ready to start which it does, but after warming and revs drop it stops running so well so I suspect the warm running needs tweaking but to try and eliminate that I let the car cool down again completely and tried starting again from cold without altering anything and it refuses to fire. Not even a splutter. After cranking for a decent time I then removed the plugs, none of which seemed wet with fuel etc so assuming it's no longer getting any. An option I possibly haven't explored with the injectors is if they weep when warm, but then again once the car cools down it still won't start. Quote Link to comment Share on other sites More sharing options...
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