2000 S10 power loss when accelerating

[ltedt]

I have a 2000 S10 high mileage 228K 4.3l

The engine starts fine and idles fine but when accelerating above 2000 rpm the enginge sputters acts like it wants to down shift and loses power.If I let off a little it smooths out some.

I changed the fuel filter but have no access to a fuel guage until tomorrow.

It seems the slower I push down the petal the better the response.

Thanks in advance!

Matt

[MT-2500]

When was you last tune up?
Any check engine lights?
Check that fuel pressure and post back readings.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

[ltedt]

Thanks for all the info, I have resolved the problem.

I really dont want to tell you how this happen but here it goes.

It all starts 3 years ago when I had hard start issues with my S10 after a few postings here and getting good info, I changed the fuel pump assembly at a cost of 300 bucks.
Well, while I removing the old assembly I had a hard time getting it at just the right angle when the float arm broke off !!! So the tank being almost full at the time I said "WTF" and left it in there. When finally it got jammed up under the new float and I have been running around thinking I had a 1/4 tank of gas ......Well it did'nt and after putting up the to the gas station and sticking in a few bucks in it. She runs like a champ now! The much less noticable hesitation I had for the last few weeks has ironed out due to the new filter I put in and all is well for the moment.

Thanks
Matt

[MT-2500]

Thanks for posting back the fix and how it went.
Glad you found the problem.

Golden rule is if it does not run put gas in it.
I have fixed many no run problems with 5 gallon of gas put in the tank.

Another golden rule is remove all old parts and count all wrenches after a repair.

Good luck