Petersubaru Posted July 24, 2006 Share Posted July 24, 2006 how important is the little canister (damper) on the end of the fuel pump..is it really needed to smoothen out the fuel injection pulses... I know if needed that a damper can be bought separately and then add-on any FI pump, provided the correct pressure is there Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 24, 2006 Share Posted July 24, 2006 If you need some, and can't find em at your local yard, I can grab a handfull next time I'm at the yard. They would fit in the USPS flat rate envelope. I see perfect ones all day long, and the yards around me have at least 20-30 SPFI soobs each right now. As to if they are needed, well the SPFI system has three of them stock - one at the pump, one right before the inlet on the TB, and one right after the outlet on the TB going to the return pipe. I would think just one would be sufficient - after the pump but before the TB. They must serve an important purpose as subaru saw fit to install three where one would have probably done the job. I'm assuming redundancy is the reason - my guess is that when the fuel pump starts to suck air when the tank is nearly empty, those dampeners smooth out the fuel flow and prevent damage to the pressure regulator and injector. Over or under voltage may also cause spikes in the pump pressure that have to be evened out. I would also guess that the pressure regulator can't adjust all that fast to changing pump pressure, and if it had to it would probably cause rapid wearing of the regulator parts. Giving it a steady stream at a constant pressure would prolong it's life - being a mechanical part, the less it has to move, the longer it will last. Anyway - just a few theorys and ideas to consider. GD Link to comment Share on other sites More sharing options...
daeron Posted July 25, 2006 Share Posted July 25, 2006 thats about exactly what i thought, except i didnt realize there were THREE of them... im relatively new to soobs, and obviously general disorder, is not. but i would say hes probably right about them wanting redundancy in there.. and lets not forget these are inexpensive little cars. if its there, what are the odds it might be superfluous? Link to comment Share on other sites More sharing options...
Petersubaru Posted July 25, 2006 Author Share Posted July 25, 2006 Thanks for the offer of going to the junk yards..later on,(hopefully sooner) I may need to buy from you other spare FI parts for my SPFI conversion,(ECU/ coil with ignitor/TB switch/ when ever I can get around to doing the conversion...There are no cars left in the scrap yards for a hundred miles around... If you need some, and can't find em at your local yard, I can grab a handfull next time I'm at the yard. They would fit in the USPS flat rate envelope. I see perfect ones all day long, and the yards around me have at least 20-30 SPFI soobs each right now. As to if they are needed, well the SPFI system has three of them stock - one at the pump, one right before the inlet on the TB, and one right after the outlet on the TB going to the return pipe. I would think just one would be sufficient - after the pump but before the TB. They must serve an important purpose as subaru saw fit to install three where one would have probably done the job. I'm assuming redundancy is the reason - my guess is that when the fuel pump starts to suck air when the tank is nearly empty, those dampeners smooth out the fuel flow and prevent damage to the pressure regulator and injector. Over or under voltage may also cause spikes in the pump pressure that have to be evened out. I would also guess that the pressure regulator can't adjust all that fast to changing pump pressure, and if it had to it would probably cause rapid wearing of the regulator parts. Giving it a steady stream at a constant pressure would prolong it's life - being a mechanical part, the less it has to move, the longer it will last. Anyway - just a few theorys and ideas to consider. GD Link to comment Share on other sites More sharing options...
skishop69 Posted July 26, 2006 Share Posted July 26, 2006 Correct, they are needed (only one actually is needed) to 'smooth out' the the fuel flow. Any pressure spike will change the actual (correct) amount of fuel the ECM has computed to be delivered from the injector. i.e. more fuel. The older regulators can't react fast enough to remove the pressure spikes caused by electrical instabilities and poor (by todays standards) pump engineering. I think it was around '96 or so almost everyone figured out how to build better pumps and do away with it. I don't think I seen one on an engine in probably 8 years. The good quality aftermarket pumps that are available do not require the use of a damper providing you have a stable supply of current. Link to comment Share on other sites More sharing options...
Petersubaru Posted July 26, 2006 Author Share Posted July 26, 2006 it was Good to have heard about the improvements..then one does not have to be so dependant upon always getting sometimes the OE products which can tend to be more expensive... Correct, they are needed (only one actually is needed) to 'smooth out' the the fuel flow. Any pressure spike will change the actual (correct) amount of fuel the ECM has computed to be delivered from the injector. i.e. more fuel. The older regulators can't react fast enough to remove the pressure spikes caused by electrical instabilities and poor (by todays standards) pump engineering. I think it was around '96 or so almost everyone figured out how to build better pumps and do away with it. I don't think I seen one on an engine in probably 8 years. The good quality aftermarket pumps that are available do not require the use of a damper providing you have a stable supply of current. Link to comment Share on other sites More sharing options...
moshem74 Posted July 26, 2006 Share Posted July 26, 2006 hi you can take them out, the less things on the fuel way=is better. i took mine out, nothing change.... take care Link to comment Share on other sites More sharing options...
skishop69 Posted July 27, 2006 Share Posted July 27, 2006 Believe it or not, it has affected your emissions and MPG. Depending on the condition of the motor, ignition, injectors, your driving style and road/traffic conditions, you may just have overlooked it. The reaction can be anywhere from negligeable to ugly. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 27, 2006 Share Posted July 27, 2006 hiyou can take them out, the less things on the fuel way=is better. i took mine out, nothing change.... take care No one said anything would change - we all stated that the dampeners are there for boundery conditions - high voltage, low voltage, pump sucking air, and other exceptional situations. That being the case, you would not notice it's absence till it's too late and your have borked your injector or pressure regulator. Think of it like a fuel filter..... would the engine run without it? Yes. Would you notice any difference by removing it? Not for a while anyway. Just because you don't fully understand the implications of removing something doesn't mean they don't exist and aren't serious. GD Link to comment Share on other sites More sharing options...
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