eyefi Posted January 9, 2004 Share Posted January 9, 2004 after a hard run (engine is hot, so is under bonnet):- have u ever seen yr fuel pressure drop after idling for >10mins? or does yr fuel pressure not drop after idling for >10mins? stock or FSE regulator? sorry to harp on about this but its driving me mad Quote Link to comment Share on other sites More sharing options...
MONKEYmark Posted January 10, 2004 Share Posted January 10, 2004 cant anyone help this dude out. he helps lots of you out. i know nothing. try to learn stuff. just replaced my starter motor on astra my first one i have done. stripped it down and cleaned and put back together, also done a fanbelt too. looks easy when you strip car down. if anyone can help eyefi out Quote Link to comment Share on other sites More sharing options...
Thorin Posted January 10, 2004 Share Posted January 10, 2004 Yeah I like to get stuck in and do more stuff too, like tonight I've just changed my car air-freshener. Quote Link to comment Share on other sites More sharing options...
Suprash Posted January 10, 2004 Share Posted January 10, 2004 Wish I could help, but this will be a Dude/Matt/Terry/CW type issue probably, how ever I must now get a fule pressure gauge fitted now..... Quote Link to comment Share on other sites More sharing options...
eyefi Posted January 10, 2004 Author Share Posted January 10, 2004 ive found a few other folk who have noticed the same problem, and a few others who know they dont have this problem. i just dont understand how a car can b mapped if the fuel pressure can fluctuate like this. unless it relys on the o2 sensor input to keep everything nice and stoich and the fpr still produces the required pressure when it gets under boost. but that just sounds wrong to me. anyway, ey up monkey, been meaning to get in touch and see how that car's getting on. thanks for the vid, nice one. thorin, welcome back. was it a dangly bit of string type freshener? u'll have to let me have a look, see how its been done, unless its a secret Quote Link to comment Share on other sites More sharing options...
Adam W Posted January 10, 2004 Share Posted January 10, 2004 You've tried swapping form the FSE regulator to a stock one and it made no difference right? Could be a problem with the vac feed to it, try tracing that line back all the way to the manifold nd making sure it's got no crud in it or anything. The vacuum should be trying to drag the pressure down at idle though, so a blockage would cause a rise in pressure . . . unless it's blocked with a wodge of old oil which is airtight when cold, then allows vacuum past it when it warms up causing the fuel pressure to drop? I had a similar problem where my BOV wouldn't "fire off" until the engine had been driven for half an hour, it wasn't seeing any signal from its vac line until it had warmed up. A long shot but all I can think of right now! Quote Link to comment Share on other sites More sharing options...
eyefi Posted January 10, 2004 Author Share Posted January 10, 2004 adam, thanks for the input. i did swap it back to stock and it still drops to 16:1, but it happens alot slower. the FPR vac pipe is new and clean and t'd from very near the MAP sensor. i think its an issue with the FSE FPR spring getting heat soaked and opening the return. it seems, from some others ive spoken to, that it is normal up to a certain point. im not sure though how it will behave if u do a full throttle run straight after its got hot, will it produce the correct pressure for the injector map? Quote Link to comment Share on other sites More sharing options...
Adam W Posted January 10, 2004 Share Posted January 10, 2004 In an ideal world the fuel pressure should always be base pressure + boost pressure. Remind me what your engine management setup is? Perhaps the mixture problems with the stock FPR are to do with the ECU reverting to settings it's learned to compensate for the faulty FSE or something? If you had a fuel pressure gauge in the cockpit it would be a lot easier to see what was happening Quote Link to comment Share on other sites More sharing options...
eyefi Posted January 10, 2004 Author Share Posted January 10, 2004 Originally posted by Adam W Remind me what your engine management setup is? Perhaps the mixture problems with the stock FPR are to do with the ECU reverting to settings it's learned to compensate for the faulty FSE or something? ems is apex power fc. the ecu is running with no o2 correction (for rough mapping purposes) and the maps r static (it doesnt self learn). some guys in the states have it with stock ecu and some with HKS VPC. Originally posted by Adam W If you had a fuel pressure gauge in the cockpit it would be a lot easier to see what was happening it certainly would, thats what im waiting for. i need something i can log as well. Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted January 10, 2004 Share Posted January 10, 2004 Sorry Eyefi, I am jumping in here without reading it all. Are you saying the AFR drops to 16:1 after a thrash, also is the pressure dropping if so how much. Something Leon & I noticed the other year was the fuel heat up after long runs. We put a temp sensor in before & after hard runs and it heated up significantly, so much so I was planning to fit a fuel cooler on the return ( never did). Voltage, have you checked the voltage is not dropping significantly? Quote Link to comment Share on other sites More sharing options...
Dragonball Posted January 10, 2004 Share Posted January 10, 2004 Have a look three quarters down Fuel Pressure Regulator and Pulse Dampener The fuel pressure regulator maintains a constant pressure across the fuel injector. The inlet manifold pressure varies with throttle angle, and engine speed. Small throttle angles and high engine speed produce low manifold pressure (high vacuum). While high throttle angles and low rpm give high manifold pressure. In addition to these conditions, low manifold pressure is associated with idle and high manifold pressure is at full throttle. It is the fuel pressure regulators job to keep a constant fuel pressure across the injector(s) regardless of manifold pressure. Currently, there are several types of fuel pressure regulators in use. Many late model cars use a return-less system where the fuel pressure regulator is mounted in the fuel tank adjacent to the fuel pump (and therefore requires no return line back to the fuel tank). In most naturally aspirated applications these types of systems are adequate. With forced induction or heavily modified engines, an adjustable fuel pressure regulator with manifold vacuum reference must be fitted. The two common types of fuel pressure regulators used are non-adjustable and adjustable. As the name implies, a non-adjustable regulator is set at a fixed value and is manifold-vacuum referenced (whenever a regulator is said to be vacuum referenced, this means that the inlet manifold vacuum/pressure is ported into the chamber above the regulator diaphragm). As manifold pressure increases, the pressure in the top chamber of the pressure regulator increases along with it, allowing the regulator to compensate for the increased demand of the fuel delivery system. Keep in mind that at idle or low throttle openings with high rpm, there is very low manifold pressure (vacuum). This tends to literally draw fuel from the injector. As manifold pressure increases (as the throttle is opened), this vacuum dissipates and it is harder for the fuel to discharge from the injector. The regulator reacts to the differences in manifold pressure to maintain constant fuel pressure across the injector. There is a spring in the vacuum (top) chamber of the fuel pressure regulator. The spring’s pressure on the diaphragm determines the fuel system’s static pressure. The system’s static pressure is the amount of pressure measured with the vacuum hose disconnected or with the engine turned off. The fuel system’s static pressure is higher than the fuel pressure at idle or under high vacuum conditions. When the engine is running, the engine vacuum acts against the spring and the effect of the vacuum diminishes as the throttle is opened. At idle, there is a high amount of fuel returned to the tank because the vacuum is pulling the diaphragm seat off of the fuel return orifice, reducing fuel pressure. As the throttle is opened, the diaphragm seat starts to close off the orifice, restricting the amount of fuel flow through the return line. An adjustable regulator allows the static pressure to be raised or lowered via an adjusting screw that acts on the diaphragm spring. On most adjustable regulators, when the screw is turned in pressure raises and when it is turned out pressure is reduced. Although we highly recommend installing a proper fuel delivery system, raising or lowering fuel pressure can compensate for fuel injectors that may not be properly sized for an application. Most aftermarket fuel pressure regulators (and OE regulators) use a 1:1 ratio of fuel to boost pressure for increasing fuel pressure in applications where forced induction is used. This means that for every psi of boost, fuel pressure is increased one psi. This ensures adequate fuel delivery under boosted conditions Quote Link to comment Share on other sites More sharing options...
Dragonball Posted January 10, 2004 Share Posted January 10, 2004 Just something that I wrote the other day:eek: There is a spring in the vacuum (top) chamber of the fuel pressure regulator. The spring’s pressure on the diaphragm determines the fuel system’s static pressure. The system’s static pressure is the amount of pressure measured with the vacuum hose disconnected or with the engine turned off. The fuel system’s static pressure is higher than the fuel pressure at idle or under high vacuum conditions. When the engine is running, the engine vacuum acts against the spring and the effect of the vacuum diminishes as the throttle is opened. At idle, there is a high amount of fuel returned to the tank because the vacuum is pulling the diaphragm seat off of the fuel return orifice, reducing fuel pressure. As the throttle is opened, the diaphragm seat starts to close off the orifice, restricting the amount of fuel flow through the return line. Quote Link to comment Share on other sites More sharing options...
eyefi Posted January 10, 2004 Author Share Posted January 10, 2004 Originally posted by Terry S Are you saying the AFR drops to 16:1 after a thrash, also is the pressure dropping if so how much. yes, u can watch it drop as u idle after a thrash. the pressure drops to (at worst) 0.5bar at idle, but i think that reading is incorrect, its from an underbonet untrustworthy source. Originally posted by Terry S Voltage, have you checked the voltage is not dropping significantly? voltage is always the same. if i take the manifold pressure hose off, the pressure jumps up (like u would expect), so the pump is fine. im gonna wait until an elec fuel pressure gauge arrives before i do any more testing. i have a feeling that the pressure drop is negligable under boost. its funny u should mention the warm fuel, i had noticed that the supply line was slightly warm in the boot. Quote Link to comment Share on other sites More sharing options...
eyefi Posted January 10, 2004 Author Share Posted January 10, 2004 paul u should b a fuel system technition Quote Link to comment Share on other sites More sharing options...
Thorin Posted January 11, 2004 Share Posted January 11, 2004 Have you tried changing the air freshner? The dangly string ones are soooo last year. Quote Link to comment Share on other sites More sharing options...
Dragonball Posted January 11, 2004 Share Posted January 11, 2004 Can someone please remind me how to convert psi into BAR Is it psi divided by 14? Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted January 11, 2004 Share Posted January 11, 2004 Eyefi, if it persists, we'll meet up somewhere and try my Aeromotive FPR on the car see if it helps. There are FPR's and then FPR's. You only have to look at the cost of the weldon one. Quote Link to comment Share on other sites More sharing options...
SimonB Posted January 11, 2004 Share Posted January 11, 2004 Originally posted by Paul E Can someone please remind me how to convert psi into BAR Is it psi divided by 14? 14.50326 Quote Link to comment Share on other sites More sharing options...
Dragonball Posted January 11, 2004 Share Posted January 11, 2004 Originally posted by Terry S Eyefi, if it persists, we'll meet up somewhere and try my Aeromotive FPR on the car see if it helps. There are FPR's and then FPR's. You only have to look at the cost of the weldon one. If you want me to send an FSE jobbie up to you to try out let me know - no obligation if it makes no diff just send it back Quote Link to comment Share on other sites More sharing options...
Guest Terry S Posted January 11, 2004 Share Posted January 11, 2004 Paul, I think Eyefi has tried an FSE already. Quote Link to comment Share on other sites More sharing options...
eyefi Posted January 11, 2004 Author Share Posted January 11, 2004 Originally posted by Terry S Eyefi, if it persists, we'll meet up somewhere and try my Aeromotive FPR on the car see if it helps. There are FPR's and then FPR's. You only have to look at the cost of the weldon one. thanks for the offer. im sending the FSE back for them to check, so if it turns out that the unit is ok i'll b asking for a refund and looking for something else. so i may take u up on that later on. Quote Link to comment Share on other sites More sharing options...
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