idosubaru Posted August 29, 2008 Share Posted August 29, 2008 i see people suggesting to clamp or partially clamp (i've read the dangers) the fuel return hose to isolate the FPR as bad. this presummably would point to a ruptured fuel pressure regulator. since the EA82 MPFI XT FPR is burried i'd like to try this test. for clamping the hose, could i pinch it shut and then drive 1/2 to one mile like that to see if the problem is fixed? car idles and rev's fine so it'll have to be a drive. does the hose need to be completely clamped or half way or what? has anyone done this or had FPR issues before? i'd be curious to know how the car drove...so i know if maybe that's similar to what mine is doing. Link to comment Share on other sites More sharing options...
McDave Posted August 29, 2008 Share Posted August 29, 2008 i see people suggesting to clamp or partially clamp (i've read the dangers) the fuel return hose to isolate the FPR as bad. this presummably would point to a ruptured fuel pressure regulator. A ruptured fpr will be bleeding fuel into the vacuum hose. Pull off the hose and check for signs of gas. for clamping the hose, could i pinch it shut and then drive 1/2 to one mile like that to see if the problem is fixed? car idles and rev's fine so it'll have to be a drive. No, don't pinch the fuel return hose off for more than a few seconds. does the hose need to be completely clamped or half way or what? It needs to be pinched off completely for a couple seconds to test for max pressure. Do as SuberDave suggested and drive the car with a pressure gauge tee-ed in to see if it will maintain the minimum pressure under all driving conditions, which also proves that the pump/fuel system can produce sufficient volume. has anyone done this or had FPR issues before? i'd be curious to know how the car drove...so i know if maybe that's similar to what mine is doing. The only symptoms I've ever seen from a bad fpr is a rich condition. Based on your second description of the symptoms in the other thread... i just drove it again. it's not just at full throttle and doesn't get better necessarily if i let off the pedal.same car that had bad fuel and a non working fuel pump, i put another one in. it'll do it any time...at take off or at highway speeds. it'll be very rythmic sometimes...accelerate for 2 seconds, decelearate 2 seconds (no power, no exhaust sound), accel 2 second, decel 2 seconds... no particular RPM, speed or gear. it's obviously much more noticeable on inclines but that might not mean much. ... I would be more inclined to believe what torxxx suggested, that it's more likely to be distributor related. Running the fuel pressure tests would be useful to rule fuel out as the problem, then I would start looking at the ignition. PS Have you checked for codes? Disconnected the test connectors when finished? Link to comment Share on other sites More sharing options...
idosubaru Posted August 29, 2008 Author Share Posted August 29, 2008 thanks MDave. yeah, no codes, idles smooth as silk at 700 rpm all day long without a blip. the FPR is a pimple on my back to get to, but i'll give it a whirl, i was hoping for a simpler way to test it without needing to get right to it. but it won't be that bad. distributors are annoying, i've seen a few fail but test fine in every way. so maybe it's not sparking during those times. fuel, spark and compression - and i know compression is perfect, so one of the others is missing, there's obviously no combustion happening when it does it. Link to comment Share on other sites More sharing options...
McDave Posted August 29, 2008 Share Posted August 29, 2008 Try disconnecting O2, tps, and maf one at a time and driving it for a short distance to see if it will run significantly different. One of them could be shorting or opening. Clean maf too. Link to comment Share on other sites More sharing options...
idosubaru Posted August 30, 2008 Author Share Posted August 30, 2008 Try disconnecting O2, tps, and maf one at a time and driving it for a short distance to see if it will run significantly different. One of them could be shorting or opening. Clean maf too. car will run without TPS hooked up? didn't know that. sweet, i'm about to leave work, so that will give me something to play with on the way home! Link to comment Share on other sites More sharing options...
McDave Posted August 30, 2008 Share Posted August 30, 2008 car will run without TPS hooked up? didn't know that. sweet, i'm about to leave work, so that will give me something to play with on the way home! It will but you'll probably have to baby the throttle to get acceleration. Link to comment Share on other sites More sharing options...
zukiru Posted August 31, 2008 Share Posted August 31, 2008 run without a MAF? mine dies instantly. Link to comment Share on other sites More sharing options...
idosubaru Posted August 31, 2008 Author Share Posted August 31, 2008 MAF - car won't run without it TPS - it ran but wouldn't idle. the problem still existed once moving O2 - no change either fairly certain we ruled out two of those three. i'm now looking into spark issues - distributor. though i'm still checking the FPR when i get a chance, going to look for fuel in the vacuum line. Link to comment Share on other sites More sharing options...
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