98 Olds Cutlass 3.1

Hey guys, I need to pick your brains. I had a no start issue that I linked to fuel pressure, it would start right away sometimes, and then sometimes crank and crank and nothing, I installed the fuel pressure guage and found that 80% of the time you turned the ignition on, the pressure would shoot up to 42 pounds and it would start normally. I finally got it to pull its "attitude" and noticed that the fuel pressure would hover at 15- 20 pounds and all it would do was crank...I looked at the schematic to see if the voltage was in any way regulated in steps from the ECM to the fuel pump. I found it to be a straight switch, so I proceeded to change the $303.00 dollar fuel pump thinking that had to be the answer. It started right up and worked well, but this morning I had to cycle the key twice to get it to pressure up. If you have had any experience with this, please let me know...its probably a .50 cent connector somewhere, but hey llive and learn.

Thanks in advance

Tom

could you hear the pump running when you cycled the key?

yes, but for some reason it stops running about 15- 20 psi, then you cycle it again, listen for it to stop and presto, 42 psi and it starts!

Once it gets up to 42 psi does it hold steady or does it drop? How long does it takew to drop. Have you checked the fuel pressure regulator to see if it is leaking? What brand or where did you get the pump?

If pressure is dropping and the regulator is not leaking than the pump is bad/defective.

It is only on the ignition phase, I checked the pressure and when it behaved properly, it went up to and held 40 psi, it was intermitent at best, but once it pressured up, it held and ran as it should. I took that as a faulty pump because of the low pressure it provided when it "acted up" I changed the pump assy and once again checked the pressure after the new pump went in, it gave me zero issues, pumped up to 42psi as soon as you turned the ignition on, however this morning I had to cycle the ignition again to get it to pump up to the required pressure, therein lies my dilemma, why wont it pump up on the first try? I thought I understood the ECM to control the voltage to the pump, however I need to know if there is a sensor that detects fuel pressure...i.e a fuel pressure regulator on this system that may be at fault.

Tom

however I need to know if there is a sensor that detects fuel pressure...i.e a fuel pressure regulator on this system that may be at fault.



No sensor.

Heres what I would do. Hook up the pressure gauge, cycle the key on and off a couple of times until the pressure is up. Make sure it is not leaking. Keep an eye on it for an hour or so. It should not drop much if at all.

I left the gauge on for over an hour to check for leakdown. I am going to test the relay when I get home. About a year ago I bypassed the theftlock system by adding resistance to the ignition wire, does anyone know if that is related? I know that it stalled the fuel system, so I wonder if something has defaulted back to an original setting?

Hey guys-
Sorry to bring up an old topic, but this is nuts. I replaced the fuel pump as I said in the earlier post, and with the fuel pressure gauge I get two seperate readings, it shoots up to 42 psi and starts perfectly, then sometimes it only goes up to 22 psi, and will crank for ever without starting. I looked at the fuel pressure regulator, and it appears to be ok (no leaks). I had a problem with the security system a year or so ago and added the required resistance in the ignition wire to bypass the keyed system. It started and ran great for quite a while, now it seems to be doing the same thing, my question is does the security system regulate the fuel pressure? could that be what is holding the pressure at 22psi when it won't start, or could there just be a sticky spring inside the fuel pressure regulator that is very intermittent? I didn't see any electrical connetions at the FPR, so I assume that it is only spring pressure that holds it.

If anybody has any clue on this plz plz plz let me know, I used to think I was a pretty good mechanic, but this has me questioning my ability!!!

Thanks in advance

Tom

Sorry, but just to add, the wife reminded me that the ignition problem we had the car would start then immediatly shut off, with that being said (and fixed) I am almost positive it is an internal spring in the FPR. Does this sound to far out of line?

Hey guys
I just wanted to let you know I replaced the Fuel Pressure Regulator last night and so far it has started and ran fine everytime!! I only wish I would have replaced the FPR first. If anyone has a diagram of the FPR and exactly how it works, I would like to have it. I can justify the fuel pump change because the car has 120k on it (better to change it in my shop than on the road) but I have to think the FPR was the culprit the whole time.

Thanks to all those who threw ideas my way!!

Tom