MaTTSuN Posted December 10, 2005 Share Posted December 10, 2005 now im getting frustrated. ive replaced my FPR fuel pump and put a gauge on my fuel rail. today i put my NEW pump in and it "seemed" to run better then when i decided to take it for a test drive the fuel pressure dies. the pump is still running but it sound like its not very strong. it wont build more than 10PSI on the rail. the fuel filter is not blocked i took it off and blew threw it. could something be clogged in the pump? or the FUEL DAMPER the reason for caps is that it is the last thing to replace on the fuel system besides the injectors........oh yeah when i tested the fuel filter the dam thing built pressure agian when i put it back together but then died again after a short brake stand grrr I HAVE NO IDEA please help Matt Quote Link to comment Share on other sites More sharing options...
MusPuppis Posted December 10, 2005 Share Posted December 10, 2005 Have you checked the voltage at the pump? Could it be possible the signal is weak and grows weaker when the electrical system is under more significant load? That could cause the problems your exhibiting I would think. I guess you've checked all the fuel lines from the tank to the engine for possible leaks? Id also replace the fuel filter - just to be sure. Quote Link to comment Share on other sites More sharing options...
MaTTSuN Posted December 10, 2005 Author Share Posted December 10, 2005 ive hooked the pump right to the battery and i checked the fuel filter i can blow threw it no problem the filter is new Quote Link to comment Share on other sites More sharing options...
MaTTSuN Posted December 10, 2005 Author Share Posted December 10, 2005 i just thought of something.... i think the line from the tank to the pump is sucking itself shut, i replaced it from the stock one but i dont think its fuel line... guess ill change all the hoses around the tank and pump tommorow. I think thats why it ran for a little while then pressure dropped, and when i took the fuel fillter off it released all the sucktion for a min then sucked itself soon after.... or at least thats what im hoping Quote Link to comment Share on other sites More sharing options...
technicalninja Posted December 10, 2005 Share Posted December 10, 2005 Might have a restriction in the metal lines in the tank. If replacing the lines doesn't help might want to check this. Quote Link to comment Share on other sites More sharing options...
MusPuppis Posted December 10, 2005 Share Posted December 10, 2005 i replaced it from the stock one but i dont think its fuel line... Yeah, you need to use EFI rated fuel line. They cost alot compared to carb'd fuel line and regular hoses but their alot stronger. Quote Link to comment Share on other sites More sharing options...
MaTTSuN Posted December 10, 2005 Author Share Posted December 10, 2005 im going to go over the whole thing today and replace all the lines and clean or blow out the metal lines will post when im done later wish me luck Quote Link to comment Share on other sites More sharing options...
MusPuppis Posted December 10, 2005 Share Posted December 10, 2005 Good luck man! Quote Link to comment Share on other sites More sharing options...
MaTTSuN Posted December 11, 2005 Author Share Posted December 11, 2005 changed the main line.... same ol thing it runs well for about 5 min maybe less then pressure starts dropping. its like the pump is turned off but it isnt. the pump is still running but it sound like its pressurized. now when i take ANY fuel line off and releve the pressure and put the line back on and try the pump it makes pressure again for 5 or so min maybe less. is this the fuel damper closing? when i let the pressure off it opens? im going 2 bypass it tommorow and see if it runns longer than 3-5 min without loosing pressure. Is it safe to do this? what does the fuel damper do? this is the last thing i need 2 change so i figure it is it... the gas lines from the tank seem to be clear... the good thing is when i started the car for the last time tonite it shoots out the coolest blue flames when i stab the gas a bunch of times so that made me happy after not fixing it with the new fuel lines Matt Quote Link to comment Share on other sites More sharing options...
Sparky Posted December 11, 2005 Share Posted December 11, 2005 have you checked the pickup tube in the tank? what might be happening is when the fuel pump turns on it sucks something up into the pickup tube and you lose pressure.....as soon as you shut it off and disconnect everything you release suction and the debris falls back into the tank? try a burst of compressed air into the pickup and try again....you might also want to drain the tank and have a look-see inside. Quote Link to comment Share on other sites More sharing options...
MaTTSuN Posted December 11, 2005 Author Share Posted December 11, 2005 taking out the fuel line with 3/4 of a tank of gas it flows very good, i even put a aluminum wire down the lineto see if it was clogged... it didnt make it any better by doing that still flowed well out the fuel pick-up. Is there a filter on the inside of the tank on a 78? im going to need to drop the tank to get the other bumper shock off but i remember the filler boot was a bear to get off my 75 when i had to do that... does it not sound like the damper? im going to bypass it tommorow and go from there i wonder if i can get my hand in the tank? might have to hire some kid to stick his hand in there haha Quote Link to comment Share on other sites More sharing options...
mark Posted December 11, 2005 Share Posted December 11, 2005 I think there is a sock or stariner type thing on the pickup in the tack. Sounds like this is sucking up debris, probably rust, take the tank down and let us know what you find. Quote Link to comment Share on other sites More sharing options...
MaTTSuN Posted December 11, 2005 Author Share Posted December 11, 2005 there is a strainer in the 78 280z? why would it drain no problem when i take the line off? it has allot of flow with just the pressure of the fuel in the tank. im thinking the damper is sucking shut somehow then letting go when i open up the system.... i tried turning the screw on the damper but it did nothing... when i pulled the bolt out of the damper ... nothing changed and i can screw it all the way in with no effort or rezistence from the inside Quote Link to comment Share on other sites More sharing options...
mark Posted December 11, 2005 Share Posted December 11, 2005 The suction of the pump will pull stuff toward the pickup. If you just open a line and let it run, no junk get sucked up. Take the dampner out of the loop and run the car with out it. I've never ran one with a FI car. Easy to tell if that is the problem. It may save you from taking the tank down. Quote Link to comment Share on other sites More sharing options...
vashonz Posted December 11, 2005 Share Posted December 11, 2005 On my stock 280zxt pump there was a small strainer on the suction of the pump, actually located inside the nipple. You don't need the dampner, just get rid of it. Quote Link to comment Share on other sites More sharing options...
Guest Loose_Screws Posted December 11, 2005 Share Posted December 11, 2005 I know there is a strainer on the '77 pumps. When I removed my pump the strainer was completely clogged! I cleaned it and put a pre-filter to help catch sediment from rusty tank. I finally gave up and put in a fuel cell. Good luck on the fuel pressure. It's either a restriction to the pump, restriction in the supply line, or the RRFR ain't working. Since the RRFR is new, I seriously doubt any issue with it. My bet is on the lines. Post up how difficult it was to replace the steel line from front to rear, I may be doing the same soon since that is the last thing on the fuel delivery to have a 'new' system. Quote Link to comment Share on other sites More sharing options...
Z24O Posted December 30, 2005 Share Posted December 30, 2005 you could try using a makeshift fuel tank to prove a point and possibly eliminate the cars tank as a problem.........like an unused(won't go boom when soldered) 1 gallon fuel(vented cap ) can with a metal pipe silver soldered in to attach your fuel line to......obviously use the appropriate caution and common sense when dealing with fuel to avoid a dangerous situation like spilling fuel in your car or having it near heat or electrical sources or if you have a friend/local business with a boat you could try those removeable self contained fuel cells good luck paul western australia Quote Link to comment Share on other sites More sharing options...
MaTTSuN Posted January 7, 2006 Author Share Posted January 7, 2006 ok i took the tank off after the hoidays and she has a mighty loa of rusty. have 2 take it to a rad shop now and clean the bad boy out. tried claning it on my own but swishing around a small amout of gas and pouring it out dont seem to do allot to the overall cleaning of the tank. "Now if this dont fix it i dont know" haha how many times have i siad that. will need a new fuel filter also hehe Quote Link to comment Share on other sites More sharing options...
TimZ Posted January 8, 2006 Share Posted January 8, 2006 I'm more inclined to think rust in the tank like everbody else, but did you ever try running with the gas cap loosened? Could be the vent lines are clogged, and the longer the engine runs, the bigger the vacuum pulled and the harder to draw fuel from the tank. This effect would probably be worse with a fuller tank (less air - the vacuum would grow more quickly). Quote Link to comment Share on other sites More sharing options...
Guest mikedick6969 Posted May 22, 2006 Share Posted May 22, 2006 I have the same problem it seems. 10 PSI. Everythings been gone through but the tank. Any tips on cleaning it out when I get it off? Or is the radiator shop the best bet? Quote Link to comment Share on other sites More sharing options...
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