96 s-10 4x4 agravation

We have a 96 S-10 ex cab lwb 4x4 With the 4.3 cpi and 4l60e. It sat unused for 3 yrs(estate headache) but at least it was drained of all fuel. It had been parked originally for trans failure. Replaced the 4l60, added 5 gal fuel and new battery and tried to start but would not untill we spared fuel into the air inlet. it idled smooth but had some hesitation in full acceleration. Treated with seafoam additive and a new fuel filter and all was good(for a short time). We have no codes or check engine light but the hesitation is getting bad. Fuel PSI is 61, fuel mpg is good(16 mpg) and do not have any signs or smells of fuel. new ign module, cap & rotor and wires and spark plugs. another new fuel filter and then fuel pump(airtec brand) with no change. Thought pcm module but it will set a code if you unplug a sensor and the Snap On Modus we have sees no problems in the pcm real time data. Vacumn is 21 at idle with my gauge, spark plugs are tan and nice, oil is clean with no fuel smell and it still acts like a carb with no accellorater pump or a really bad vacumn leak but we have none of that. The old 283 4bbl is starting to look good at this point.
Anybody have any ideas on where else to look or something we missed?
Any help will be greatly appreciated!

If this is a vortec, I would check into the cpi unit. It's often called a spider injection assembly and is located in the upper intake. When u check the fuel pressure with engine off does it hold for 5 minutes? If not, the fuel regulator diaghram could be bad. This should be obd II, does scanner register any misfires? You also need to unplug connector on top of intake and check resistance on all 6 injectors and check to make sure all injectors are receiving a signal. You can do this with a noid light or a dvom.

We have a 96 S-10 ex cab lwb 4x4 With the 4.3 cpi and 4l60e. It sat unused for 3 yrs(estate headache) but at least it was drained of all fuel. It had been parked originally for trans failure. Replaced the 4l60, added 5 gal fuel and new battery and tried to start but would not untill we spared fuel into the air inlet. it idled smooth but had some hesitation in full acceleration. Treated with seafoam additive and a new fuel filter and all was good(for a short time). We have no codes or check engine light but the hesitation is getting bad. Fuel PSI is 61, fuel mpg is good(16 mpg) and do not have any signs or smells of fuel. new ign module, cap & rotor and wires and spark plugs. another new fuel filter and then fuel pump(airtec brand) with no change. Thought pcm module but it will set a code if you unplug a sensor and the Snap On Modus we have sees no problems in the pcm real time data. Vacumn is 21 at idle with my gauge, spark plugs are tan and nice, oil is clean with no fuel smell and it still acts like a carb with no accellorater pump or a really bad vacumn leak but we have none of that. The old 283 4bbl is starting to look good at this point.
Anybody have any ideas on where else to look or something we missed?
Any help will be greatly appreciated!

Airtex fuel pumps are junk.
They are a :nono::nono: on newer fuel injected GM V6 and V8 engines.
Very few of them produce the correct fuel pressure or last very long.
The Delphi is the only good fuel pump for them.

Snap on modus is a good scanner but you have to read the data in between the lines.
They do not set a code for all problems.
Watch you fuel trim and 02 sensor readings for any signs of low or hight fuel pressure that will show lean or rich running engine.

First thing check you fuel pressure for up to specs.
60/66 lbs.
You will need 64-65 lbs engine cranking for a good cold start.
And 63-65 engine running on the road.
Where and how did you check and get the fuel pressure reading of 61 lbs.
Post back your cold start engine cranking and engine running fuel pressure and truck on the road fuel pressure.
And remember fuel pump is not what controls fuel pressure.
It only has to produce pressure and volumn up and over the regulated pressure.

As far as checking the fuel pressure we have adapter sets that allow you to tap into the fuel system anywhere there is an threaded or snap connection in the fuel pressure side of the line. we tapped in on the outlet of the fuel filter. It was driving down the road, holding the fuel psi gauge in one hand and driving, 61 was the lowest we saw and that was at full throttle. 66 psi cranking pressure 65 at idle. As to fuel trim it is almost always trying to lean it out. We are thinking maybe a gasket went by by and will pull the upper and lower pleneum and check that next. The regulater seems ok as every one we had go out had fuel in the vacumn line and we don't have that.

As far as checking the fuel pressure we have adapter sets that allow you to tap into the fuel system anywhere there is an threaded or snap connection in the fuel pressure side of the line. we tapped in on the outlet of the fuel filter. It was driving down the road, holding the fuel psi gauge in one hand and driving, 61 was the lowest we saw and that was at full throttle. 66 psi cranking pressure 65 at idle. As to fuel trim it is almost always trying to lean it out. We are thinking maybe a gasket went by by and will pull the upper and lower pleneum and check that next. The regulater seems ok as every one we had go out had fuel in the vacumn line and we don't have that.

You are welcome for the thank you.
Fuel pressure sounds good.

Could be vacumn leak and also check MAF sensor and air intake hoses.
Let us know how it goes.

After setting so long, I'd suspect that there is quite a bit of varnish in the system from any residual fuel remaining after it was drained. I'd recommend running some good fuel injector cleaner through it to remove any that may have come loose and restricted the injector flow. Advance Auto has Techron on sale right now. http://www.automotiveforums.com/vbulletin/showthread.php?t=1061861

When I say drained this is what I mean- Ran it untill it died from lack of fuel. The fuel tank (Damaged in off road incident) was dropped and sent in for repairs, that was when the lawsuit started so when the tank came back it was reassembled and that was that. What is really strange is if you pull off a larger vacumn line it will turn on the check engine light but rehook it, clear codes and it stays off.

Update- today the hesitation is mostly gone(42 Degrees outside) but the check engine lite came on saying O2 sensor bank 2 was not working properly, seems very strange, O2 sensor bad-truck runs good.

When I say drained this is what I mean- Ran it untill it died from lack of fuel. The fuel tank (Damaged in off road incident) was dropped and sent in for repairs, that was when the lawsuit started so when the tank came back it was reassembled and that was that. What is really strange is if you pull off a larger vacumn line it will turn on the check engine light but rehook it, clear codes and it stays off.

Update- today the hesitation is mostly gone(42 Degrees outside) but the check engine lite came on saying O2 sensor bank 2 was not working properly, seems very strange, O2 sensor bad-truck runs good.

What is the deal on lawsuit or you referring to the lawsuit as your problem on it?

Sounds like you need to fix the 02 sensor problem.

When I say drained this is what I mean- Ran it untill it died from lack of fuel. The fuel tank (Damaged in off road incident) was dropped and sent in for repairs, that was when the lawsuit started so when the tank came back it was reassembled and that was that. What is really strange is if you pull off a larger vacumn line it will turn on the check engine light but rehook it, clear codes and it stays off.
The tank mounted fuel pump pushes fuel; as soon as it runs dry the pressure stops leaving fuel in all the lines, injectors, and even in the injector tubes because without pressure it won't get past the poppit valves.

What is the deal on lawsuit or you referring to the lawsuit as your problem on it?

Sounds like you need to fix the 02 sensor problem.It sounds like the lawsuit was a probate issue and not related to any mechanical issues on the vehicle... other than not being able to touch it for 3 years.

The tank mounted fuel pump pushes fuel; as soon as it runs dry the pressure stops leaving fuel in all the lines, injectors, and even in the injector tubes because without pressure it won't get past the poppit valves.

It sounds like the lawsuit was a probate issue and not related to any mechanical issues on the vehicle... other than not being able to touch it for 3 years.

Thanks
For clearing that up Blazee
Looks like.
I did not read between line on first post.