LT1 has spark but no fuel pressure
08-05-2011, 03:03 PM
#1
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LT1 has spark but no fuel pressure Okay this may sound like an obvious fuel pump problem but the fuel pump is brand new. Vehicle is 96 camaro z28. Has a fuel pressure tester on schrader valve and it reads 0psi while cranking and while the pump primes. Its a brand new TRE 255 pump with brand new fuel filter. Tested opti at school and its fine, brand new ICM, brand new spark plugs and brand new wires. Pulled the wire out of the ICM and it sparks while cranking. Hooked it back up and pulled the other side out of the opti, it sparks while cranking. After cranking a few times all I smell is unburnt fuel from the engine bay. All fuses are good. After sitting for a few mins the car will act like its going to start but then just goes to back to just cranking. Any ideas?
08-05-2011, 05:44 PM
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No, I can't really use it on another vehicle because the other two that I have don't have schrader valves. I suppose I could try it on a friends, but the gauge was brand new out of the box and I have measured 34psi with that gauge on this car Before I replaced the factory pump for this TRE. The car ran fine until connections came loose in the tank and I had to reconnect those. This pump has been a nightmare since day one.. But its brand new..
08-05-2011, 10:43 PM
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08-06-2011, 12:30 AM
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Pop off the larger fuel line at the fuel rail, the feed one. Hold it in a bucket and have a buddy put the key to "on" but don't start crank the engine.
When the pump primes, you should have a good gush of fuel into the bucket.
BE CAREFUL of splashed fuel. NO SMOKING!
When the pump primes, you should have a good gush of fuel into the bucket.
BE CAREFUL of splashed fuel. NO SMOKING!
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08-06-2011, 11:02 AM
#9
Not to swipe the thread, but: My Chilton's shows a "prime" lead in the fuel pump circuit. Any one know where it is? Would be helpful for the OP.
Al 95 Z28 with two Walbro 255's in the tank
Al 95 Z28 with two Walbro 255's in the tank
08-06-2011, 11:07 AM
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For some reason I've had to muck around with a fuel pressure gauge to get it to read pressure on the Schraeder valve whether the gauge is used or new. Try unfastening and refastening it several times.
The only thing that will tell you is if the pump works just enough to move fuel. Doesn't tell you at what pressure which can mean a lot.
08-08-2011, 06:52 PM
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Above post really didn't serve me any help but....
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Okay I pulled the fuel pump assembly out and found that there was a pin hole sized hole in one of the two fuel lines. I replaced both fuel lines to be safe and put everything back together(all wiring was hooked up and looked up to par). Primed the system and still reading 0 psi. Went back and pulled the fuel lines above the tank apart and fuel sprayed everywhere, so the lines are priming, but why is there no fuel pressure?
I then unhooked the number one spark plug wire and put o screw driver very close to the end socket of the wire, no spark jumped. Replugged it in and unplugged the wire going from the opti to the coil, from the coil side and did the same thing, no spark. Plugged it back into the coil and unplugged the other end going to the opti, had spark. So i have narrowed it down to Opti, ICM, or Fuel pressure regulator. I also removed the vaccuum line on the back of the regulator and no fuel came out. Couldnt get back there to smell, but im guessing its fine. Any thoughts or Ideas before I just start replacing stuff till the problem is fixed?
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Okay I pulled the fuel pump assembly out and found that there was a pin hole sized hole in one of the two fuel lines. I replaced both fuel lines to be safe and put everything back together(all wiring was hooked up and looked up to par). Primed the system and still reading 0 psi. Went back and pulled the fuel lines above the tank apart and fuel sprayed everywhere, so the lines are priming, but why is there no fuel pressure?
I then unhooked the number one spark plug wire and put o screw driver very close to the end socket of the wire, no spark jumped. Replugged it in and unplugged the wire going from the opti to the coil, from the coil side and did the same thing, no spark. Plugged it back into the coil and unplugged the other end going to the opti, had spark. So i have narrowed it down to Opti, ICM, or Fuel pressure regulator. I also removed the vaccuum line on the back of the regulator and no fuel came out. Couldnt get back there to smell, but im guessing its fine. Any thoughts or Ideas before I just start replacing stuff till the problem is fixed?
08-08-2011, 07:00 PM
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Can u hear the pump cycle by turning on key? Did you install the filter with it flowing the correct way? Have you pulled a supply line off at the rails and cycled key to see if it's making it to the rails?
Last edited by defaultexistence; 08-08-2011 at 07:11 PM.
