Doulou Posted May 5, 2020 Report Share Posted May 5, 2020 Morning all I have had a situation for some time now where by when the engine is cold the engine cranks over for around 10 seconds before firing, once fired everything runs fine. My question is, , is there an O ring fitted to the fuel rail other than the one inside the fuel pressure regulator itself? I am thinking that my fuel pressure isn’t high enough and may be leaking from somewhere on the fuel rail or pressure regulator, causing the excessive cranks. also thought it’s worth mentioning that the fuel pump is new. I may be well of the mark so any help appreciated. thanks Paul Quote Link to comment Share on other sites More sharing options...
sailorbob Posted May 5, 2020 Report Share Posted May 5, 2020 I would expect that if you have a fuel leak sufficient to cause cranking issues then you would also be having issues during higher fuel demand. Put a fuel pressure gauge on the fuel rail and see what pressure you are getting during KOEO and how quickly it drops after the fuel pump stops priming. Then see what happens to the pressure during cranking. Quote Link to comment Share on other sites More sharing options...
Doulou Posted May 5, 2020 Author Report Share Posted May 5, 2020 Thanks Bob i will order a fuel pressure testing kit would you happen to know the name of the adaptor on the FPRV when ordering the kit I want to make sure I get the correct one thanks again Paul Quote Link to comment Share on other sites More sharing options...
sailorbob Posted May 5, 2020 Report Share Posted May 5, 2020 It's a Schrader valve, I think it may be SAE 7/16-20 sized. Quote Link to comment Share on other sites More sharing options...
Doulou Posted May 5, 2020 Author Report Share Posted May 5, 2020 Perfect thank you Quote Link to comment Share on other sites More sharing options...
Doulou Posted May 5, 2020 Author Report Share Posted May 5, 2020 Sorry one more question what should the pressure be? Quote Link to comment Share on other sites More sharing options...
sailorbob Posted May 6, 2020 Report Share Posted May 6, 2020 I just measured a spare FPR and the test port diameter is 11.09 mm with 20 threads per inch so the SAE 7/16-20 size looks to be correct. The Delco fuel pressure regulator is nominally rated at 3 bar but the specs in the Lotus Service Notes and GM workshop manuals and are a bit 'loose' with a range of about 3.5 psi either side being quoted as being acceptable. Quote Link to comment Share on other sites More sharing options...
Doulou Posted May 7, 2020 Author Report Share Posted May 7, 2020 Thanks Derek, the kit should arrive on Saturday so I will let you know what the numbers are. Paul Quote Link to comment Share on other sites More sharing options...
ragingfool35 Posted May 8, 2020 Report Share Posted May 8, 2020 the fuel pressure does bleed away after sitting for a while. There is a 2 (or 3) second fuel pump activate each time the ignition switch is turned to the ON position for this reason. wait for the fuel pump to finish before cranking, see if that helps Quote chris90SEjust because I don't CARE doesn't mean I don't UNDERDSTAND Link to comment Share on other sites More sharing options...
Doulou Posted May 12, 2020 Author Report Share Posted May 12, 2020 Morning all so I have just measured the fuel pressure, on ignition while fuel pump is priming I get a little over 3 bar, but once the pump stops it rapidly drops to around 1 bar. Can I crank / start the car with the pressure gauge attached? thanks Quote Link to comment Share on other sites More sharing options...
sailorbob Posted May 12, 2020 Report Share Posted May 12, 2020 Yes, you can start the engine with the gauge attached as it is only tee'd into the fuel rail. The rapid bleed down of pressure could be due to a fault in the pulsation damper fitted to the fuel pump. There's a post from Vulcan Grey giving details on this problem If you do need to replace the damper use SAE J30R10 hose. Quote Link to comment Share on other sites More sharing options...
Doulou Posted May 12, 2020 Author Report Share Posted May 12, 2020 Thanks Derek what is the pulsation damper? I cannot find it in the parts diagrams Quote Link to comment Share on other sites More sharing options...
sailorbob Posted May 12, 2020 Report Share Posted May 12, 2020 Lotus only supply it as part of the pump assembly. Quote Link to comment Share on other sites More sharing options...
Doulou Posted May 12, 2020 Author Report Share Posted May 12, 2020 Yes I just found the section you referred fromTravis however I don’t have any running problems no fuel starvation or lack of boost. Also there is no smell of fuel anywhere would it be useful to take a pressure reading while cranking and with engine running? thanks And thinking about it we replaced the fuel pump in the hope of curing this problem but it never did Quote Link to comment Share on other sites More sharing options...
sailorbob Posted May 12, 2020 Report Share Posted May 12, 2020 It does not take much of a leak to drop the fuel pressure when the pump isn't running. Also, you can be running lean and not notice a drop in performance but exhaust temperatures can soon rise. I had a fuel pressure regulator go faulty on my MR2 turbo and it boosted fine but the turbo soon ran extremely hot and went bright red. Quote Link to comment Share on other sites More sharing options...
Doulou Posted May 12, 2020 Author Report Share Posted May 12, 2020 Is there any way of checking if it’s running lean? Would a free scan tell anything? Quote Link to comment Share on other sites More sharing options...
sailorbob Posted May 12, 2020 Report Share Posted May 12, 2020 An exhaust gas analyzer or wideband lambda sensor is the definitive way. You can possibly use the BLM values but it's not guaranteed as the learning only occurs during closed loop fuelling and you may only be going lean during times of higher fuel demand such as when in open loop fuelling. Quote Link to comment Share on other sites More sharing options...
Doulou Posted May 12, 2020 Author Report Share Posted May 12, 2020 Ok thanks Derek, I may well be wrong, but I think we’re heading in the wrong direction with this. I am still leaning towards the FPRV, but I have no way of checking because I cannot buy one. thanks for your help, and should I find the problem I will let you know what it was. Quote Link to comment Share on other sites More sharing options...
ragingfool35 Posted May 13, 2020 Report Share Posted May 13, 2020 wow they are no longer available....Tom Mieczkoski probably has some used ones. i think i gave him 2 from me. I made this in 2014 to utilize an aftermarket regulator on mine. fuel rail adapter.PDF Quote chris90SEjust because I don't CARE doesn't mean I don't UNDERDSTAND Link to comment Share on other sites More sharing options...
Doulou Posted May 13, 2020 Author Report Share Posted May 13, 2020 Yes absolutely none available and I am not skilled enough to fabricate one. I will put a plea out there to see if anyone has one sitting around thanks Quote Link to comment Share on other sites More sharing options...
sailorbob Posted May 13, 2020 Report Share Posted May 13, 2020 They can still be found as 'new old stock' and pattern part equivalents, there's several of the latter currently on eBay. Quote Link to comment Share on other sites More sharing options...
Doulou Posted May 13, 2020 Author Report Share Posted May 13, 2020 Hi Derek, I must be missing something I have search everywhere but cannot find, can you send a link? Quote Link to comment Share on other sites More sharing options...
sailorbob Posted May 13, 2020 Report Share Posted May 13, 2020 Go to ebay.com and search for 'pr103 fuel' in eBay motors (there's even a Herko branded one for under a fiver). Quote Link to comment Share on other sites More sharing options...
Doulou Posted May 13, 2020 Author Report Share Posted May 13, 2020 Wow just shows if you know what your looking for!! thanks Derek, I will make a point of letting you know how I get on Paul Quote Link to comment Share on other sites More sharing options...
Chillidoggy Posted May 13, 2020 Report Share Posted May 13, 2020 I have a good used spare FPR on the shelf if required. Strangely, I’ve just had a message from Sparky asking the same question. Odd! Quote Margate Exotics. Link to comment Share on other sites More sharing options...
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