bignum Posted December 24, 2008 Share Posted December 24, 2008 (edited) I need to know what should happen to fuel pressure after the engine is shut off, ie how long and what pressure compared to static. Mine drops to about 2 psi after 5 seconds or so which i reckon is not helping my hotstart problem at all, cheers. Oh, merry christmas all. Edited December 24, 2008 by bignum (see edit history) Quote Link to comment Share on other sites More sharing options...
Terminator Posted December 24, 2008 Share Posted December 24, 2008 I need to know what should happen to fuel pressure after the engine is shut off, ie how long and what pressure compared to static. Mine drops to about 2 psi after 5 seconds or so which i reckon is not helping my hotstart problem at all, cheers. Oh, merry christmas all. What set up have you got? Quote Link to comment Share on other sites More sharing options...
bignum Posted December 24, 2008 Author Share Posted December 24, 2008 What set up have you got? I`m using my uk pump with an aeromotive fpr and p/e 800cc injectors/hks rail, aem ecu. Quote Link to comment Share on other sites More sharing options...
dandan Posted December 24, 2008 Share Posted December 24, 2008 When you try the next hot start you could turn ign on for about 2 secs then off for about the same....then repeat maybe three times. Then crank straight away.......fuel pressure would have definitely build up from the pump priming during those initial "ign on" events. See how that fares....might give you another piece of info for diagnosis Quote Link to comment Share on other sites More sharing options...
paul mac Posted December 25, 2008 Share Posted December 25, 2008 I need to know what should happen to fuel pressure after the engine is shut off, ie how long and what pressure compared to static. Mine drops to about 2 psi after 5 seconds or so which i reckon is not helping my hotstart problem at all, cheers. Oh, merry christmas all. really wouldn't think it would effect hot start but mine holds pressure for 20 ish minutes (i've never timed it), it may indicate some other problem in the fuel system, has it just developed this problem ? or is it an ongoing issue with the ecu Quote Link to comment Share on other sites More sharing options...
bignum Posted December 25, 2008 Author Share Posted December 25, 2008 Its been a problem since i fitted the injectors/rail, ecu etc. Quote Link to comment Share on other sites More sharing options...
paul mac Posted December 25, 2008 Share Posted December 25, 2008 i think all ecu's (aftermarket and stock) have a hot start function and it sounds like yours isn't setup, do you have an AFR gauge if so you could watch what you are getting whilst trying to fire it up and post it here, it wont mean jack to me but i'm sure some ecu type would be able to confirm whats what Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 25, 2008 Share Posted December 25, 2008 It should hold the rail pressure for many many minutes, if not hours. There should be a none return valve in the pump, and the injectors shouldn't bleed down, and the FPR should hold pressure. So it's basically a leak somewhere. It certainly won't help hot starting, low rail pressure can cause vaporisation. Leaky injectors cause flooding, blah balah. Quote Link to comment Share on other sites More sharing options...
bignum Posted December 26, 2008 Author Share Posted December 26, 2008 It should hold the rail pressure for many many minutes, if not hours. There should be a none return valve in the pump, and the injectors shouldn't bleed down, and the FPR should hold pressure. So it's basically a leak somewhere. It certainly won't help hot starting, low rail pressure can cause vaporisation. Leaky injectors cause flooding, blah balah. I think i`m getting a vapour lock chris,as my hotstart problem only happens if the car is upto temperature and is left for half an hour or more, i`m going to find out which part of the system is at fault by clamping off the return to test the fpr then before the rail to test pump return valve and injectors, cheers for the input guys Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 26, 2008 Share Posted December 26, 2008 I would first suspect the FPR, then the injectors, assuming no external leak. Quote Link to comment Share on other sites More sharing options...
bignum Posted December 26, 2008 Author Share Posted December 26, 2008 I would first suspect the FPR, then the injectors, assuming no external leak. I hope it is the FPR chris, it will be the easier and cheaper fix, Quote Link to comment Share on other sites More sharing options...
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