fuel pressure regulator question
sherman69
10-25-2005, 02:08 PM
Hi,
My truck (97 K1500 5.7) is losing fuel pressure quite fast after turning off the key.
I had it stall after starting and put it in gear. Several times.
62 lbs while the pump is running, But down to 50 while the engine is running. It drops to 20 in a few seconds after the pump is off.
If I clamp the return line, the pressure goes up to 80 but still drops to 20 or less when the pump is off.
The shop manual is a bit confusing in the diagnostic flow chart.
What is a good way to decide if it is the fuel pressure regulator or the fuel pump check valve?
The fuel pump is only 5-6 months old, Delphi brand.
Thanks,
Bob B
My truck (97 K1500 5.7) is losing fuel pressure quite fast after turning off the key.
I had it stall after starting and put it in gear. Several times.
62 lbs while the pump is running, But down to 50 while the engine is running. It drops to 20 in a few seconds after the pump is off.
If I clamp the return line, the pressure goes up to 80 but still drops to 20 or less when the pump is off.
The shop manual is a bit confusing in the diagnostic flow chart.
What is a good way to decide if it is the fuel pressure regulator or the fuel pump check valve?
The fuel pump is only 5-6 months old, Delphi brand.
Thanks,
Bob B
obadran
10-26-2005, 10:55 PM
The pressure shouldn't drop off that fast. Are you having any other problems such as accelaration hesitation that goes away after a few minutes when you first start up after sitting for a long time?
I have a 96 5.7 so I'm not sure if the 97 is the same. Do you have CFI fuel injection. To me it sounds like a fuel pressure regulator problem. From what I learned when my fuel pressure regulator went bad, if you have a CFI system, the regulator leaks gas into the intake manifold. This extra fuel could be causing a rich condition that could be the cause of the stalling engine.
Hope this is useful.
Omar
I have a 96 5.7 so I'm not sure if the 97 is the same. Do you have CFI fuel injection. To me it sounds like a fuel pressure regulator problem. From what I learned when my fuel pressure regulator went bad, if you have a CFI system, the regulator leaks gas into the intake manifold. This extra fuel could be causing a rich condition that could be the cause of the stalling engine.
Hope this is useful.
Omar
sherman69
10-27-2005, 09:03 AM
The filter is new now as is the pressure regulator. No help yet.
I didn't drive far when is began the other day, because it was stalling.
Yes it has the central cfi system.
Bob B
I didn't drive far when is began the other day, because it was stalling.
Yes it has the central cfi system.
Bob B
sherman69
10-27-2005, 04:07 PM
OK I made a mistake when going down the diagnostic chart.
Turns out it now blames the 6 month old fuel pump.
So I added my own test: i pulled the fuel lines from the injector block and put a piece of hose on the supply line from the tank and clamped it off. The symptoms are the same, good pressure with power on the pump
and when I cut off the power, the pressure drops fairly fast.
So with just the fuel line and the pressure gauge involved. it has to be the pump .
I already ordered the Warantee replacement from NAPA for tomorrow.
Thanks for the helpful ideas.
Bob B
Turns out it now blames the 6 month old fuel pump.
So I added my own test: i pulled the fuel lines from the injector block and put a piece of hose on the supply line from the tank and clamped it off. The symptoms are the same, good pressure with power on the pump
and when I cut off the power, the pressure drops fairly fast.
So with just the fuel line and the pressure gauge involved. it has to be the pump .
I already ordered the Warantee replacement from NAPA for tomorrow.
Thanks for the helpful ideas.
Bob B
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