2eighTZ4me Posted June 30, 2010 Share Posted June 30, 2010 (edited) As the title says, I'm losing fuel pressure under boost and going terribly lean. I upped fuel pressure to 42psi last night, and made a few runs. When the car gets warm/hot, I lose HALF of the fuel pressure when the car goes under boost. Drops to about 18-22psi. MS1 fuel only. Idle AFR's and cruise are 10.8-13.2. When the car gets hot, they go up to about 12.2 - 14.4. Aeromotive A1000 fuel pump through Aeromotive filter - all Aeroquip -8 AN from the pump up to the front. Converts down to -6AN just before hitting the fuel rail. Return is -8AN as well. Fuel is not boiling. I can touch the fuel line and it's not even warm. If I let off the gas under boost, pressure comes right back to 42. This pump should supply this car easily. There's no way I'm making more than 350hp right now. This pump should supply a car with double that. I'm thinking I have a pinched line somewhere?? As the car gets hotter, the fuel hose becomes more pliable and cuts off more fuel. It didn't do this a couple months ago. I could boost until the cows came home. Only in the hotter weather is it prevalent. OR - could the drop from -8 to -6 prior to the fuel rail be an issue? I have no idea at this point. Any ideas??? Do I need a freakin' surge tank??? Edited June 30, 2010 by 2eighTZ4me Quote Link to comment Share on other sites More sharing options...
zxtman Posted June 30, 2010 Share Posted June 30, 2010 As the title says, I'm losing fuel pressure under boost and going terribly lean. I upped fuel pressure to 42psi last night, and made a few runs. When the car gets warm/hot, I lose HALF of the fuel pressure when the car goes under boost. Drops to about 18-22psi. MS1 fuel only. Idle AFR's and cruise are 10.8-13.2. When the car gets hot, they go up to about 12.2 - 14.4. Aeromotive A1000 fuel pump through Aeromotive filter - all Aeroquip -8 AN from the pump up to the front. Converts down to -6AN just before hitting the fuel rail. Return is -8AN as well. Fuel is not boiling. I can touch the fuel line and it's not even warm. If I let off the gas under boost, pressure comes right back to 42. This pump should supply this car easily. There's no way I'm making more than 350hp right now. This pump should supply a car with double that. I'm thinking I have a pinched line somewhere?? As the car gets hotter, the fuel hose becomes more pliable and cuts off more fuel. It didn't do this a couple months ago. I could boost until the cows came home. Only in the hotter weather is it prevalent. OR - could the drop from -8 to -6 prior to the fuel rail be an issue? I have no idea at this point. Any ideas??? Do I need a freakin' surge tank??? Check your FPR first. How old is that pump? Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted June 30, 2010 Author Share Posted June 30, 2010 I already checked the FPR - I ran a gauge out of it through the hood. It's brand new, as is the pump. Less than 1000mi. on both components. Quote Link to comment Share on other sites More sharing options...
sq_creations Posted June 30, 2010 Share Posted June 30, 2010 I would say its either the fuel pump or voltage going to the fuel pump. Can you log the voltage. Just because a fuel pump is new doesn't mean it can't go bad. Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted June 30, 2010 Author Share Posted June 30, 2010 Already pulled datalogs and submitted them to a second set of eyes - Matt at DIY AutoTune. Voltage is dead constant throughout the whole ordeal. Running a GM alternator. Every other parameter is also spot on as well - save for AFR. Matt confirmed. Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted June 30, 2010 Author Share Posted June 30, 2010 Also, just to clarify, I have felt the fuel pump and the lines in the engine bay when it's acting like this. Both are cool to the touch. No evidence of heat soak or anything. Quote Link to comment Share on other sites More sharing options...
zxtman Posted June 30, 2010 Share Posted June 30, 2010 Do you feel a power loss or have detonation when your fuel pressure guage reads 18-22psi under boost? If not, your gauge is probably bad. Try a different gauge. I do not trust those little 1" fuel pressure guages, if that's what you're using. Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted June 30, 2010 Author Share Posted June 30, 2010 No - it's an AutoMeter Phantom gauge 2 5/8", and it checks out in perfect step with the 1" gauge too. Power loss - definitely, but I have my timing a bit retarded, and never build enough boost to get into detonation before it goes bone lean and falls flat on its' face. I've pretty much determined it's the Aeromotive pump. I should have bought the other one (11106) and not this POS A1000 - which appears to be only for strip usage. It has a caveat that you need to buy a voltage regulator to the tune of $320 if you intend on running the car for more than 30min. at a shot. What a crock of shizzle.......dang dang dang and shame on me..... they advertise it as one thing on Summit's website, and then when you get down to the nitty-gritty of the install guide - you find out ALL the other crap you have to buy to make it work right. I'm pretty sure that's the issue. Can't confirm 100%, but I'm leaning that way. Quote Link to comment Share on other sites More sharing options...
zxtman Posted June 30, 2010 Share Posted June 30, 2010 No - it's an AutoMeter Phantom gauge 2 5/8", and it checks out in perfect step with the 1" gauge too. Power loss - definitely, but I have my timing a bit retarded, and never build enough boost to get into detonation before it goes bone lean and falls flat on its' face. I've pretty much determined it's the Aeromotive pump. I should have bought the other one (11106) and not this POS A1000 - which appears to be only for strip usage. It has a caveat that you need to buy a voltage regulator to the tune of $320 if you intend on running the car for more than 30min. at a shot. What a crock of shizzle.......dang dang dang and shame on me..... they advertise it as one thing on Summit's website, and then when you get down to the nitty-gritty of the install guide - you find out ALL the other crap you have to buy to make it work right. I'm pretty sure that's the issue. Can't confirm 100%, but I'm leaning that way. I am not a fan of the A1000. Read this thread. http://forums.hybridz.org/index.php?/topic/31350-some-pictures-of-my-fuel-setup/page__p__266060__fromsearch__1#entry266060 Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted June 30, 2010 Author Share Posted June 30, 2010 I just got off the phone with Brett at Aeromotive. He seems fairly confident we can make this work. That other post mentioned the pump getting too hot. Not in my case. I can touch it easily and hold my hand on it after at least an hour or so of driving. It's barely warm. He did mention though that the pump moves about 3 gal./min. so if you chalk up 30+ hours of usage, that's thousands of gallons of gas going through the filter element. I am ordering new filter elements today, along with a pre-pump filter. He also recommended plumbing the cell for -10AN fittings, of which I am only running -8AN, and that, he stated, is also causing a restriction. I asked if I would be better off with the 11106 or the new Tsunami pump, and he stated I would probably run into the same problem. When I asked about the voltage regulator device - his response was that it was nothing more than a CYA, and generally not necessary. He seemed more concerned about possible cavitation being caused by the fuel not being able to be brought to the pump in a quick enough manner. Hence - go up to the -10 hose from the tank to the pump. That's going to be my cheapest route at this point. He went on to say that even if I did go with the Tsunami pump, or the 11106, that I would still want -10 lines from the tank to the pump. I'm also going to get another one of those 1" gauges (that I can tell you distrust) and plumb it inline between the pump and the filter so I can see differential pump pressures between what the pump head is putting out and what is actually making it past the filter up to the rail. I'm relieved to hear that I don't have to plunk down for a new pump and/or voltage regulator - but yet cautiously optimistic that this might solve the issue. I'll keep you all posted in the coming days/week or so. Quote Link to comment Share on other sites More sharing options...
SATAN Posted July 3, 2010 Share Posted July 3, 2010 It sounds like you are already in the process of replacing the filter element. I had a similar issue (actually, exact same issue). I pulled the element and could not even blow air through it, that's how clogged mine was AND it was less than a month old. Although, this would not explain how temperature effects the situation. That is the only thing that confuses me. Quote Link to comment Share on other sites More sharing options...
Mayolives Posted July 5, 2010 Share Posted July 5, 2010 As the title says, I'm losing fuel pressure under boost and going terribly lean. I upped fuel pressure to 42psi last night, and made a few runs. When the car gets warm/hot, I lose HALF of the fuel pressure when the car goes under boost. Drops to about 18-22psi. I don't understand the temp. thing but I use the A1000 with two of their filters with -8 plumbing. I had a simular problem last year and my filters needed to be changed. That pump will provide all the fuel you should need for your set up. Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 5, 2010 Share Posted July 5, 2010 To jump in and be redundant, that sounds like a classic case of a plugged filter. Fine as long as there is no demand on the system, perfect pressure. But put some load on it, fuel pressure drops and as soon as you lift your foot it returns. Insufficient flow on the pumping end to keep up with the demand side (injectors)---usually a plugged filter. The question is, when you boost stone cold, are you saying this does NOT happen (you mention it only happens when hot?) During warmup, this filter issue should be even more pronounced as it's on the 'warmup loop' with slightly higher pulsewidths. Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted July 5, 2010 Author Share Posted July 5, 2010 I replaced all the plumbing from the pickup tube to the pump with -10an. I had blown out the 10 micron filter that was before the pump with the air compressor, and that still didn't seem to make any difference. I replaced the lines with -10AN lines and replaced the 10 micron filter with the recommended -10AN inline filter - 100 micron. Everything is great now, but don' t know if it was the clogged filter or whether it was the larger input lines that made the difference. Would be willing to bet it was a clogged filter. Thanks to all that responded!!! Quote Link to comment Share on other sites More sharing options...
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