Anyone Checked fuel pressure on their 3.4L?

[95DGcamaro]

Well I am having problems with my car, fuel related. But we put a fuel pressure gauge on the car, and when the key is turned, I can only get around 16psi... and while the car is running I can only get about 30psi. These numbers seem really low no matter what car. And absolutely NO PLACE has the recommended PSI for the 3.4L. I even have the actual GM service books that are like 240000 pages and it is not listed for the 3.4L.

So my question is, has anyone hooked up a gauge and got PSI numbers on a normal running 3.4L. It would be very useful for myself and the rest of the members.

Thank you,
Scott

[98Camaro3.8]

My Haynes manual has it, and I'm sure the GM service manual does as well.

Engine off, pump on: 41-47 psi.
Engine running (idle): - 3-10 psi.

[ May 23, 2005, 11:40 PM: Message edited by: 98Camaro3.8 ]

[95DGcamaro]

That says it for the 3.4L? or just all pre-97?

because thats the number in mine for all pre-97, which is not exactly accurate.

[98Camaro3.8]

Why is that not accurate? 95 is before 97, isn't it?

[3.4 slow to go]

I'm suprised the car is actualy running w/that smallamount of psi running through there. How accurate is the gauge???

Engine off, pump on: 41-47 psi.
Engine running (idle): - 3-10 psi.

go w/that

[95DGcamaro]

The gauge is fine, just bought it. It's the one that literally connects to the piping.. and then has the release valve (with tubes and such). I know, it is weird, because the car runs fine, which boggles my mind.

I just say it is not exactly accurate because the 1995 3.8 does not run that PSI. I assume that must only mean the LT1's. Because if the 3.8 is running a different PSI, than most likely the 3.4 is as well. I was just wondering if somewhere it directly says for a 3.4L it needs to be this and this at idle, etc.

And ya, a good estimate is about 40-50psi. I was just wondering if any other 3.4 actually tested their cars. Just was hoping to get the actual number.

Thanks, Scott

[98Camaro3.8]

3.8s run 49-55.

Isn't it possible that the LT1 and L32 happen to run near the same pressure?

viper98885 seems to agree: http://www.camarov6.com/ubb/ultimate...c;f=1;t=013518

My GM factory service manual says 41-47 psi on the 96 3.4, which is pretty similar to yours.

Try testing with the engine off (pump on) and see what pressure you get.

FWIW, I've had 2 fuel pressure gauges from Autozone. Both lasted 1 day before they busted seals and started leaking everywhere....total crap.

[ May 24, 2005, 01:49 AM: Message edited by: 98Camaro3.8 ]

[95DGcamaro]

Well I'm pretty sure my pump is shot, and I am replacing it in about a week.

The gauge is fine, it works on my dad's 98 SS. Reads 51psi.

My car without idling, just with key on is only 16psi. doh. That is why I need to replace it.

p.s. what 1996 3.4 are u talking about? 95 was the last year for 3.4 in the camaro/firebirds.

[98Camaro3.8]

Originally posted by 95DGcamaro:
p.s. what 1996 3.4 are u talking about? 95 was the last year for 3.4 in the camaro/firebirds.

That was in some van, but it's similar to yours. ;)


How long after turning the key on did you measure the fuel pressure? The pump is only on for a few seconds, then it turns off. Once the pump shuts off, the pressure may drop a little...and if your fuel pressure regulator is bad it'll really drop fast.

[95DGcamaro]

Originally posted by 98Camaro3.8:
How long after turning the key on did you measure the fuel pressure? The pump is only on for a few seconds, then it turns off. Once the pump shuts off, the pressure may drop a little...and if your fuel pressure regulator is bad it'll really drop fast.

We watched it right at the time of ignition. And my regulator and injectors seem fine because it holds pressure for hours after I put pressure to the lines.

Although, we do know it is the pump now, because it is getting worse and at about 3000RPMS the power cuts suddenly as the pump cannot keep up with the required fuel.

So now it is just time to drop the axle and the exhaust and take out the old one and plop in a new one (minus some finagling due to the new pump being a walbro 255).

-Scott

*edit - where is the best place to pick up a walbro 255lph pump? do i need the high pressure or just the standard?

[ May 25, 2005, 12:56 AM: Message edited by: 95DGcamaro ]

[TheV6Bird]

Just a little off topic: How do you release the fuel pressure to plug in the FP gauge on a 3.4? I remember when I changed my fuel filter, no one could tell me how to release the pressure, so I just said "screw it" and got gas all over myself when I took off the fuel filter.

Is there a valve to release the pressure?

[95DGcamaro]

I do not know exactly, my dad was putting the gauge on. It goes on that middle nozzle thing (need a diagram) and it should lose all pressure once you open it. That is if the car is off and the ignition as well. Might need to take off the vacuum line right next to it so it doesn't hold pressure.

I will get back to you later tonight when my dad gets home.

-Scott

[yellowfbod]

you release pressure at the shrater valve next to the FPR, it looks like a valve stem