Second opinion on fuel pressure gauge results

Question

1989 Buick LeSabre w/ a 3800 vin C. Fuel pump has around 70k miles. The fuel pump is supposed to be around 40PSI at idle but I don't know how accurate the guage is from Harbor Freight.

Heres the pressure readings:

Engine off for about an hour: 0 PSI

Turn Ignition to "on": Jump to 10 psi but slowly drops back down to zero in about 15-20 seconds

On Startup: Jumps to 35-40 PSI

At Idle: Stays right at 35 PSI (A tad on the low side, eh?)

On idle roughness/burps: Pressure drops 1-3 PSI when the idle goes bad...

Bumping the Throttle: Goes down to 32-33 and then jumps back up to 35-36 after its been goosed a bit

At this point I could see fuel starting to build up behind the lens of the pressure tester.... what the heck?? So I killed the motor and its sitting outside now.

However, I think these results are clear that I have issues with fuel. The filter has around 20k miles on it so I think I'm going to try to change that ASAP. I dropped by O'Reily and they have a FPR for around $80 where autozone has one for $30. Will I be OK getting the AZ unit or should I wait?

Ultimately, it could be my fuel pump going out. The pump is original to the engine which has around 70k miles on it which to me seems a bit low for a factory pump.

Thoughts, suggestions on which route I should go in first?

Answer 1

1989 Buick LeSabre w/ a 3800 vin C. Fuel pump has around 70k miles. The fuel pump is supposed to be around 40PSI at idle but I don't know how accurate the guage is from Harbor Freight.

Heres the pressure readings:

Engine off for about an hour: 0 PSI

Turn Ignition to "on": Jump to 10 psi but slowly drops back down to zero in about 15-20 seconds

On Startup: Jumps to 35-40 PSI

At Idle: Stays right at 35 PSI (A tad on the low side, eh?)

On idle roughness/burps: Pressure drops 1-3 PSI when the idle goes bad...

Bumping the Throttle: Goes down to 32-33 and then jumps back up to 35-36 after its been goosed a bit

At this point I could see fuel starting to build up behind the lens of the pressure tester.... what the heck?? So I killed the motor and its sitting outside now.

However, I think these results are clear that I have issues with fuel. The filter has around 20k miles on it so I think I'm going to try to change that ASAP. I dropped by O'Reily and they have a FPR for around $80 where autozone has one for $30. Will I be OK getting the AZ unit or should I wait?

Ultimately, it could be my fuel pump going out. The pump is original to the engine which has around 70k miles on it which to me seems a bit low for a factory pump.

Thoughts, suggestions on which route I should go in first?

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I' d Use an LPG System.

Answer 2

if you have a "return" fuel system the fuel pressure regulator might be at fault, especially because u have no residual pressure. the FPR might be leaking fuel back to the tank instead of trapping it in the fuel rail for the next startup. Ur fuel pump might be at fault but i would do that last cuz its the most expensive