Fuel Pressure
10-13-2012, 11:30 PM
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Fuel Pressure Hey guys i have a quick question, I have hard starts with my lt1, like it cranks for a while before it fires, also i have fuel starvation or ignition problems at 5500rpm and up. I used to rev it to 6k no problem full motor was rebuilt and cammed,full exhaust, headers, port and polished heads and lt4 intake bigger injectors and dyno tune. Anyway i put a fuel pressure gauge on it and i have 50 psi and prime with car not running but as soon as the 3 or so seconds the pump is on it immediately drops to 0 Psi, at idle without the vacuum line off, its at 42 psi, and when i rev it it increases. Is this the FPR, is it a failing fuel pump?
10-14-2012, 11:30 AM
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i've heard a lot of bad things about the aeromotive adjustable fpr, if you still have a good stock one i'd swap that out, could also be a bad check valve in the pump too... the check valve is what cause long hard starts for me
10-17-2012, 06:56 PM
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You just answered your own question 42.5psi & hold it Not drop it in 3 seconds LoL Get a Racetronix with a Hot Wire kit Then for the 5500 Whens the last time you done a Complete Tune Up???
10-17-2012, 08:14 PM
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Well that doesnt answer if its the FPR or the Fuel pump. I heard good things from racetronix but i do not believe that my fuel pump is the problem. Im going to try a stock FPR for now and see if it holds pressure on prime. I'll let you know. Motor only has about 10k on it did opti plug wires and plugs when it was rebuilt. Fuel filter about 1k ago and oil change.
10-17-2012, 08:34 PM
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What brand of Opti though??? A/C Delco is the best way to fly Delphi is right there too Accel Optis fail pretty quick since theyre made in China now 
Did you loctite the screws on the rotor?? When the thing wont hold prime for more than 3 seconds its 99.9% a fuel pump in my book pull the vac line & see if you smell fuel from the AFPR Bet you dont 
Ive got a Holley AFPR on my fuel rail incase I need to bump up the pressure from needing bigger injectors than 42lbers but less than the next size up for my 396 build If it makes ya feel better Ive got my tech diplomas for Seadoo, Suzuki, Yamaha & Chrysler Usually dont tell everyone about Chrysler LoL
Did you loctite the screws on the rotor?? When the thing wont hold prime for more than 3 seconds its 99.9% a fuel pump in my book pull the vac line & see if you smell fuel from the AFPR Bet you dont Ive got a Holley AFPR on my fuel rail incase I need to bump up the pressure from needing bigger injectors than 42lbers but less than the next size up for my 396 build If it makes ya feel better Ive got my tech diplomas for Seadoo, Suzuki, Yamaha & Chrysler Usually dont tell everyone about Chrysler LoL Trending Topics
10-18-2012, 04:02 AM
#8
Pull the vacuum line off the regulator and see if there is fuel in it.
AFPRs usually complicate things for those who don't understand its purpose. They are a handful of instances where they have actually LEAKED causing engine fires in the past so for that reason alone I wouldn't use an Aeromotive.
Having said that I use a 18 year old stock FPR on my 455whp 383 without a problem.
AFPRs usually complicate things for those who don't understand its purpose. They are a handful of instances where they have actually LEAKED causing engine fires in the past so for that reason alone I wouldn't use an Aeromotive.
Having said that I use a 18 year old stock FPR on my 455whp 383 without a problem.
10-18-2012, 06:34 AM
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OEM FPR's are the way to go. Ive read alot of bad reviews about aftermarket ones.
If thats not the case id say your fuel pumps starting to fail. Might not be atrong enough to support your new build.
If thats not the case id say your fuel pumps starting to fail. Might not be atrong enough to support your new build.
10-18-2012, 07:20 AM
#10
Pull the vacuum line off the regulator and see if there is fuel in it.
AFPRs usually complicate things for those who don't understand its purpose. They are a handful of instances where they have actually LEAKED causing engine fires in the past so for that reason alone I wouldn't use an Aeromotive.
Having said that I use a 18 year old stock FPR on my 455whp 383 without a problem.
AFPRs usually complicate things for those who don't understand its purpose. They are a handful of instances where they have actually LEAKED causing engine fires in the past so for that reason alone I wouldn't use an Aeromotive.
Having said that I use a 18 year old stock FPR on my 455whp 383 without a problem.
10-18-2012, 07:49 PM
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What brand of Opti though??? A/C Delco is the best way to fly Delphi is right there too Accel Optis fail pretty quick since theyre made in China now Did you loctite the screws on the rotor?? When the thing wont hold prime for more than 3 seconds its 99.9% a fuel pump in my book pull the vac line & see if you smell fuel from the AFPR Bet you dont Ive got a Holley AFPR on my fuel rail incase I need to bump up the pressure from needing bigger injectors than 42lbers but less than the next size up for my 396 build If it makes ya feel better Ive got my tech diplomas for Seadoo, Suzuki, Yamaha & Chrysler Usually dont tell everyone about Chrysler LoL
Did you loctite the screws on the rotor?? When the thing wont hold prime for more than 3 seconds its 99.9% a fuel pump in my book pull the vac line & see if you smell fuel from the AFPR Bet you dont Ive got a Holley AFPR on my fuel rail incase I need to bump up the pressure from needing bigger injectors than 42lbers but less than the next size up for my 396 build If it makes ya feel better Ive got my tech diplomas for Seadoo, Suzuki, Yamaha & Chrysler Usually dont tell everyone about Chrysler LoL