Guys,

What should the stock fuel pressure be for my 05? I put a gauge on it today to diagnose a somewhat hard start, and I only have 4-5 psi. What should I be seeing?

thanks!

 

I believe it is 16-18 psi

 

It depends on what pump you are using and where you are checking the line pressure. If the pump is engine mounted and the fuel is cold, that would be minimum. If the truck has the in-tank pump, the feed pressure is between 6 to 8 PSI. This is checking the feed pressure at the high pressure pump inlet banjo fitting.

 

I have an in-tank pump, and I'm checking at the banjo bolt at the inlet of the CP3. I have used two different test gauges, and they both tell me 4-5psi. I also have a bleeder on my test gauges. I let it bleed overnight and I am still getting air out of it. This doesn't make a lot of sense to me... the tank is completely full, and the pump is in the tank. Where's the air coming from? I don't have any leaks.

Alldata says I should have 80psi.... I know 80 is not correct, but 4-5 seems pretty low. I also have a new fuel filter.

Thanks

 

Is there a screen in the pump/pickup unit? This truck has spent most of it's life sitting, so maybe it's full of bacteria, etc?

 

Air in your gauge line has no effect on the gauge reading. Pressure is pressure. What does make a difference is that you should be using a diaphragm separator on the feed pressure gauge line. I do and run antifreeze from diaphragm to gauge. Running a fuel line to the gauge in the cab is very dangerous.

On the low pressure thing, is the pressure you are stating at idle or under heavy throttle? I would place a temporary gauge at the filter inlet and see what the line pressure is. You should not drop more than 2 PSI across your filter, if you are, you probably have a restriction there.

 

In tank lift pump on 05 should provide 9 psi at cp3 with a new fuel filter.

 

I just have a test gauge zip-tied to the power steering pump lines, so all I can really measure is idle. I do have diaphragm separator I could use to see the pressure from the cab. Will the pump actually increase the fuel pressure at higher rpm?

I'll see if there's a fitting on the fuel filter header I can test.

 

The pressure will not increase at higher rpm.
Actually it decrease at higher rpm when you step on the go pedal.
At idle 9 psi.
At wot min 2 psi was considered good.
4-5 psi was low at idle. Your pump was dying or you have flow restrictions.

 

Fuel pressure will drop as the fuel oil viscosity rises. It is not unusual to see feed pressure drop to 5.5 psi in the winter at start up until the fuel warms up in the filter canister. This is measured at the CP3 with an in-tank pump. However, after just a short while, the pressure will climb to at least 7 psi in the winter.

 

Makes sense. Tomorrow I plan to install a gauge in the cab with the correct diaphragm separator, and drive the truck. I'll make sure I'm always maintaining pressure, and I'll drop the tank after I've burned all the fuel.

I'm thinking I've got dirt and crap in the tank/in the pickup unit.

 

Randy,
Actually you are making a guess. There is no reason why you cannot define the location of the pressure drop before any disassembly takes place. It is not a difficult job to rig up a fuel line pressure gauge and place it first at the fuel tank and then at the filter inlet just as you have done at the CP3. It could save a lot of work.

 

Well that's a good idea. If banjo snubber fittings weren't so expensive I'd probably set up these gauges to be permanent.

By the way, how do you like your 6-gun?

 

The six gun has been great. I installed the Six Gun with atainless 4" exhaust, manifold and waste gate in 2004, all Banks stuff. It does not make the power levels of others out there, but I still have my original injectors. The other power boxes kill injectors. The Banks stuff is conservative. I rarely use power settings beyond position 3 and just leave it there. The best reason to use the Banks equipment has been the mileage increase. It has been worth between 1 and 2 MPG.

 

Truck in signature, fuel pressure at idle with stock in-tank fuel pump (the stock fuel pump has no problems delivering fuel through all the filters)