Vortec Fuel pressure on the low side

VortecJeep

VortecJeep

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Joined
Aug 24, 2005
Location
Concord, NC
1993 4.3 CMPI Vortec V6 in my YJ.

Just replaced the fuel pump (external, E2000) and fuel filter. No leaks. Fuel pressure is reading 46-48psi at idle. If I rev it up, it peaks out at 55psi, but then quickly comes back down to around 46-48psi even holding the higher rpms. I believe spec is 55-61 psi. Don't know what the pressure was with the old pump, never checked it before it died on me. Did I get a faulty pump? Is there a problem with the fuel injection spider? The spider is the only thing I did not replace when I rebuilt the motor last spring. Can anything be damaged by the lower fuel pressure?
 
bump
 
im not completely positive, but there should be a regulator on your fuel line, typically located on or near the motor... they will probly regulate the pressure down to ~6-10 psi, maybe a little more... so i say it shouldnt be a problem, but idk
 
Put a volt meter on your pump, if your voltage is floating a little that could account for that little bit of PSI change at idle. Make sure your not having supply issues, collapsed hose etc..
 
If you're holding it under no load, your vacuum signal will get higher as you hold it meaning you won't get that increase you're looking for. You should probably drive it and check the pressure then, I think it'll stay around 55.
 
Rich said:
If you're holding it under no load, your vacuum signal will get higher as you hold it meaning you won't get that increase you're looking for. You should probably drive it and check the pressure then, I think it'll stay around 55.
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Do you mean check press. while driving or drive, then check pressure in driveway?
 
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