Did some work, now it won't start?

[70L34]

Hey everyone,

I have a Pontiac 455 with a FAST B-B, WB02 system. Got the car to run pretty well last year, so I have been driving it for a while. A couple of weeks ago, I decided to adjust the throttle blades at idle because it seemed the IAC was working too hard. While doing this, the car sputtered and died and couldn't be restarted. Saw some seepage from the fuel pressure regulator and replaced it with an Aeromotive. I haven't touched it since.
Tried starting the car today and the most I can get out of it is an occasonal fire for a split-second. Most of the time it seems like it's not firing at all, but occasionally I will hear it spark and spin up, but it hasn't actually run. I have played around with the cranking fuel with no success. Tried increasing the starting IAC position, that didn't seem to do anything either. FYI I have a MSD distributor (locked out), and the signal is sent to a 6AL.
Looks like all the sensors on the dashboard are working. Battery voltage has gone down from all this starting and now sits at about 11.3V.
This is driving me nuts...any ideas? Thanks in advance,

Tony

 

[70L34]

This is probably a dumb question to add, but then again, maybe not! I just realized that it's been a while since I filled the car up with gas. I did crack the fuel line on the rail and it's definitely pressurized, and some fuel did spray out. Fuel pressure gauge on the regulator is reading around 35psi if I prime the pump for 20sec. So my question is--could there be an insufficient amount of fuel to run the motor, despite the gauge reading adequate fuel pressure?

Thanks again,
Tony

 

[bobc455]

35 PSI seems low for most injectors. But if that's where it's always run, then okay.

I assume that you watched the pressure *during cranking*, and it didn't drop? If it still maintains pressure, then the fuel pumjp is working fine. If the fuel pressure drops off from 35, then your fuel pump needs some work.

Other than that, it does sounds like a lack of fuel during cranking.

Did you put a timing light on the motor to make sure you're still sparking?

-Bob Cunningham
bobc@gnttype.org

 

[70L34]

Hi Bob,

Thanks for the reply. I haven't checked yet for spark...I'll put a light on it tonight and let you know what happens.

Regards
Tony

 

[WaterPog]

Originally posted by 70L34
...I just realized that it's been a while since I filled the car up with gas...

how long is a while, maybe the gas has gone bad and just doesn't have the energy to start the car?

 

[Glen]

After checking spark and fuel pressure will cranking and these are Otay, try holding the throttle open just a bit and crank. Some times closing the throttle just alittle is alittle too much irregardless of IAC position. With a closed throttle I have seen some cars still not start even with a boat load of IAC.

Simply put, U can't have fuel pressure without fuel. Any air and pressure drops.

 

[70L34]

Hmm...

Went out to the garage this afternoon and put a timing light on the #1 cylinder. It's firing. Fuel pressure gauge on the regulator will go to around 30 psi with the pump priming...which begs the question...shouldn't it ideally pressure up to 43 psi if that's where the regulator is set? Or does that only occur when the engine is running?

The car really sounds like it wants to start. It cranks and spins up (fires for a second), but it just won't run. Thanks for the ideas so far!

 

[bobc455]

With the engine off, the pump should easily attain it's setpoint while priming. If your regulator is set to only 30, then that's all you'll see. But I bet it should be set around 45.

If it won't go any higher than 30, then the pump may be limiting it, and I would suspect that your pump is toast.

Can you set the regulator to a higher pressure?

-Bob Cunningham
bobc@gnttype.org

 

[70L34]

Hey Bob,

That is kind of what I expected to hear. I have tried to set the new Aeromotive regulator to get the lines primed to 43 psi but it doesn't seem to go above 30. I'll go back out to the garage, readjust the regulator, and see if I can hit my pressure target.

Thanks again,
Tony

 

[70L34]

Fuel pressure shot up to 60psi after I dumped a couple of gallons of gas into the tank. I'll try to fire it up tomorrow...but I think that did it! It's amazing that I waited days to check the most obvious thing...oh well.