Fuel Pump Question

[87SFI]

I'm running 15#'s of boost and half the time when I go WOT I get 820mv on my o2's and 0 knock and the other times I get low to mid 700's and 5 counts of knock. Is this a possible faulty fuel pump? I do not have a external fuel gauge to read pressure while I drive.

Thanks
George

 

[strikeeagle]

George,

What kind of pump? How old?
Do you have a hotwire?
What kind of FPR?
Injectors?
Inspected lines and hoses for kinks?
Changed fuel filter lately? What kind?
Voltage at pump?

Having a rock solid fuel supply is step one...

 

[87SFI]

hotwired 307 (5 years old)
bosch adjustable regulator set at 43lbs
40# injectors
new fuel filter (fram)
Did not check voltage at pump, but that's a good idea.
This started happening after I put a roller cam in.

Thanks
George

 

[Steve Hill]

a problem that comes-and-goes like this can drive ya nutty.

When this happens sometimes it's better to elminate known variables.

I suggest you start with monitoring fuel pressure.
What I did is make up a very long, high pressure hose attached to a large FP gauge. I temporairly fixed this to my windshield so I could monitor FP under real-time conditiions.

I was very surprised to discover how many fp regulators can be off, and in different ways.
After that experience I no longer trust ANY fp regulator before testing it, even expensive ones right out of the box.

 

[blackbuick87]

How old is that regulator? Dont see too many Bosch adjustables.

 

[87SFI]

Originally posted by blackbuick87
How old is that regulator? Dont see too many Bosch adjustables.

It's about 7 years old, but only 5,000 miles of use. I had it laying around. I really don't think anything is wrong with that.

Thanks

 

[blackbuick87]

After 7 years of being in fuel dont rule anything out. If its rebuildable I would have it done as maintenence. But Steve's suggestion of putting the FP gauge on the windshield will tell if you have erratic FP, and if you do look at the regulator

 

[87SFI]

Originally posted by blackbuick87
After 7 years of being in fuel dont rule anything out. If its rebuildable I would have it done as maintenence. But Steve's suggestion of putting the FP gauge on the windshield will tell if you have erratic FP, and if you do look at the regulator

I bought it 7 years ago new and installed it 1 year ago. I'll try to mount my gauge to my windshield. What should I look for as far as an erratic FPR? Would a weak or bad pump give me erratic readings too?

Thanks for the replies!
George

 

[blackbuick87]

Fuel pressure should be very close to your base setting (line off) plus boost. If it wavers when you are getting KR and low O2's you have your problem. Have someone with you so you dont wreck