Pocho86

Ok so this truck is supposed to be a flex fuel truck because there is two different inline fuel filter set ups per NAPA and mine has two nipples on one side and one on the other.

2003 Chevrolet S-10
2.2L 4 Cylinder
2 Wheel Drive

What initially started this was my neighbor is a older relaxed person so he inst the type that just goes from off straight into crank kind of person, he will go off then acc, then on then crank in a matter of like 4-5 seconds. Now since he does it slower when the fuel pump primes, it bleeds back before he hits cranks so then there is like no pressure in the rail, so as he cranks the fuel pump is trying to prime with lower system voltage cause of cranking then it starts about 3-5 seconds after cranking.
When I check pressure at the rail, it builds up to 35PSI and then drops straight to zero when the pump cycles off WHEN TURNING THE KEY TO ON. I did change the fuel pump and previously my pressures were at 23-25PSI then drop off to zero.
I figured the fuel pump had a check valve inside of it and it was causing it to just back drain but after replacing the whole assembly I was wrong but did achieve better pressures.
So I guess I am trying to find out WTF is causing the fuel to bleed backwards like this, and if any one had ever heard or had this problem before. Some thing is obviously not right and I do not want to Jerry Rig things to make it work correctly. Usually on cold starts he says it will start right up but mostly when it is warmed up after a drive it will be a little difficult. My neighbor did say that it does start alot better then it did before but I told him, i heard your truck starting a few times and its not supposed to be like that. If I can have any ideas, diagrams of the fuel system or some advice I would appreciate it.

EinST

It sounds like your problem is the fuel pressure regulator. On the 2.2L, it sits on the fuel rail and has a vacuum hose attached to it (reacts to manifold vacuum and raises the fuel pressure when needed). It may even be leaking fuel into the vacuum hose which is why it starts up better after a cold soak.

Pocho86

I looked at the rail very very good and there is NO regulator unless its some messed up place like underneath. I also did talk to Napa to see if they had a fuel pressure regulator and they said they don't have a listing for it, in other words because it doesn't have one.
The fuel line comes up from the passenger side by the ignition coil and has a bend back towards the rail but hooks up to the rail on the "front of the engine" side of the rail. The truck is supposed to be a flex fuel because of the inline fuel filter style according to NAPA. The engine is a VIN H and the engine has 2200 on the cover by the throttle body. Any help is so deeply appreciated.... Thank you.

Pocho86

Also looking at online parts catalog, the 6 cylinders only have the regulator.

EinST

Oops, now I see that they did something cute with the "VIN H" LN2 engine for 2003. They integrated the fuel pressure regulator into the fuel filter. One of the two supply lines on the fuel filter is actually the fuel return line. So, one or more fuel injectors are bleeding down (would cause other driveability problems) or the fuel filter/regulator is probably shot.

Pocho86

yea I remember changing the fuel filter in frame about 6 months ago and it did not really change performance.... I know there in two stub outs on one side of the filter and the other side just has one. I guess because of that, its a flex fuel inline filter. So the filter is were the check valve is at? and if thats not my loss for fuel pressure or drop of fuel pressure with key on then its a injector?

EinST

No, a check valve is something that allows flow in one direction only, like found in fuel pumps. The fuel filter on this vehicle has the pressure regulator built in, i.e., the mechanism that bleeds excess pressure through the fuel return line. Since I do not know the quality of parts or workmanship involved, barring an external leak, I can only say your choices are injectors, fuel filter, and fuel pump.

in2pro

Without knowing this vehicle, but gauging by its age I would put my bet on the injector leaking... I would think that a poor performing injector would leave its mark on the spark plug or possibly in the oil pan by excessive gasoline in your oil... does the oil smell like it has fuel in it?

Pocho86

Alot of cars that are gas have the slight smell of it in the engine oil. my brand new 11 frontier i did the first oil and it had a hint of smell in it, comparing the two trucks i would say they are the same. The spark plugs I changed and the wires and they looked fine, just a little worn nothing alarming.

What would be my best bet if the fuel pressure primes to 32PSI with key on and then a immediate drop to 0 when pump cycles off?
-I would figure a leaking injector would bleed slowly cause of the orfice size...

Pocho86

also there is no drivability problems, its just starting when it is warm takes a few slight seconds more then when it is cold... Its hard to diagnose alot of **** with out the proper tools and stuff but i am a heavy equipment mechanic by trade and dont have alot of this little car special tools and testing stuff.