Fuel Pressure diagnostic help

[robertmee]

I was reading in another thread about Fuel PSI dropping w/ key on then off indicating stuck injectors. So, curious, I decided to try mine and low and behold, seeing some weird behavior.

Vacuum off, Fuel PSI set to 43, Vacuum on around 38.

Step 1 - Gauge at 0
Step 2 - Turn on Ignition
Step 3 - Hear Pump run about 3 to 5 seconds
Step 4 - Gauge builds to 38 PSI
Step 5 - With ignition on or off, pressure starts to drop pretty fast to around 18 PSI, I'd estimate within 10 seconds
Step 6 - At 18 PSI, Gauge stops dropping and holds. Didn't wait for an hour to see, but it pretty well stops moving

Running issues, Car smells rich, but O2 and WB indicate a bit lean.

Do I have something amiss here?

 

[DailyDrifter]

Just drive the car and stop over-reacting like a woman :biggrin:.

 

[Razor]

The pressure bleed down is either injectors or fuel pump.

If its injectors it will be hard to start and show up on sparkplugs.

If its fuel pump.. all plugs will look the same.

It could also be your regulator not seating properly.

 

[robertmee]

Just drive the car and stop over-reacting like a woman :biggrin:.

Or I could not have a car to drive and cry like a baby :tongue: How's that workin' out for you? :wink:

 

[robertmee]

The pressure bleed down is either injectors or fuel pump.

If its injectors it will be hard to start and show up on sparkplugs.

If its fuel pump.. all plugs will look the same.

It could also be your regulator not seating properly.

I'm curious now.....I've always maintained that the car smells rich, but the o2 says otherwise. Doesn't the O2 sensor get its reading from 2-4 cylinders only? Could it be possible that I could read lean from 2-4, but one or more injector(s) 1-3-5 are stuck open causing richness?

Throw into the mix that the PSI bleeds down to 18 or so and not all the way to 0. I would think multiple injectors stuck open would quickly bleed it to 0 (or maybe just 1 open).

Guess it's time to yank the spark plugs (need to regap them anyway) and check for fuel. Would it be good to 'prime' the system a few times (ignition on/off) and then pull them to see if they are wet with gas?

How do you check the regulator? I seem to remember that pinching off some hose with needlenose can verify leakdown at the regulator but I can't find that thread now.

 

[GN owner]

Go to: Vortex Turbo Buick Performance

Select Troubleshooting on the left side of the screen and then select Fuel Pressure Test on the menu.

Hope this helps!

 

[robertmee]

Thanks!