Fuel Pressure q's

[Edwindo]

So based on some earlier questions I had, I went ahead and borrowed a fuel pressure gauge to check my pressures. Finally got time to start in on it, found the fitting on the rail, pulled the little cap off, hooked up the gauge and started testing.

Well, the gauge registered no pressure when I turned on the key. Tried several times, couldn't ever get it to register. Thought maybe the gauge I got was bad. Took it apart, made sure there wasn't a blockage. Then I realized I couldnt even get fuel to come out when I hit the little bypass button on the gauge.

So, I took the gauge off the rail fitting, and then with the key on and the pump pressurized, I used a screw and pushed the valve in. I got a tiny little drip of fuel, and then nothing. I could hold the valve in and no fuel came out. So, I am thinking that my pressure is so low that its actually not registering, but why isn't it at least putting out a stream when I open the valve?

The regulator and the check valve are all in the pump on an 03, correct? I'm thinking its way past time for a new pump. Oh well.

 

[Edwindo]

And one more thing: My expy runs. This is not a no-start issue.

 

[K5rnt]

What happened on my 99 was the pressure would bleed off when the truck was not running. I thought it was the check valve so I bought a fuel pump. When I dropped the tank I found that the rubber hose that connects the pump to the metal live was cracked and the clamps holding it on were loose. So that is where I was loosing my pressure. I went ahead and changed the pump since I already had it and had it out but I'm sure I could have gotten away with just replacing that hose and clamps.

 

[K5rnt]

Oh yeah. My symptoms were the truck would turn over for about 10 to 15 seconds before it would start. Now it busts right off every time.

 

[Edwindo]

Hmm, I'll have to take a look at the lines coming from the tank. Mine does start hard, but only cranks for 3-5 seconds if I go from cold. Been cycling the key to build the pressure so it doesn't have to crank so hard. I just don't understand why when the key is on there's nothing more than a tiny little dribble, and then it stops from the valve on the rail. Should have a constant stream, even if there's some loss, I would think. ?????

 

[K5rnt]

Did you check the pressure when it was running or just key on?

 

[Edwindo]

Just key on. Guess I could check it running too, huh? Just kinda got sidetracked by the initial findings

 

[K5rnt]

When you turn the key on the pump will only run a few seconds so it's hard to get a pressure reading that way. When you accelerate hard under load like a big hill does the engine clatter?

 

[Edwindo]

No, no clatter. And I just went out and started it with the key on while the gauge was on, and still no pressure. Maybe the little valve has some debris in it? I really don't think that could happen, not enough to block it completely anyway...

 

[Edwindo]

What else can I check? It's obviously getting fuel, because it starts, runs, and drives, WOT and everything. It does have a slightly rough idle, which is what started me on checking this, since poor fuel pressure can produce a rough idle.