S10 bogs under acceleration

[charger912]

I have a 1994 Chevy S-10 2.2L that idles fine and revs fine when out of gear, but when you give it more than 50% throttle under load it bogs and won't accelerate any faster. The only problem code showing is 12. So far I have replaced the air filter, fuel filter, fuel pump & screen, IAT sensor, TPS, O2 sensor, spark plugs, cat, and muffler. The only other thing I can think of is possibly the MAP sensor, but there are no problem codes. Maybe the new fuel pump was bad. God I hope not. Anybody else ever had a similar problem?

Thanks for any advice at all!

[MT-2500]

Check and post back fuel pressure at idle and engine cranking and on the road after warm up running pressure.
Also watch pressure when it is bogging down.
Check and post back engine vacuum at isle and at 2 K RPM.
Post back readings.
MT

[charger912]

Originally Posted by MT-2500

Also watch pressure when it is bogging down.

Any advice on how to safely check the fuel pressure while driving b/c the truck only bogs when driving? My Haynes manual says that I need to connect the pressure tester right after the fuel filter. Driving and leaning out the door check the pressure would be a bit difficult/dangerous to do at the same time. Or should I put the truck on jack stands to keep the back wheels off the ground allowing them to spin freely. I'm not sure if this idea would work quite as well since there wouldn't be much more load. Sorry if I sound naive!!!

[MT-2500]

You need to test on the road with a good load on it.
It may run all day inside shop with no problem.
I had one that would run all day inside and as soon as I drove it out driveway it would quit.
Get a long hose for your gauge and tape or tie it to outside rear view mirror or outside of windshield.
Also if you have to tie in at fuel filter tie up fuel line hose so it does not hang down and drag.

I like to test drive run a pump 20 -30 minutes for a good hot test.
You have got to have fuel pressure and fuel volume to.
Post back how it goes.

[charger912]

I have been thinking that the fuel volume may be my problem. I'll try get the test done this weekend. MT-2500, I really appreciate your help! Thanks.

[MT-2500]

You should have 9-13 lbs of fuel pressure.
With return line blocked off you should se 15-20 full fuel pump pressure.
Good luck
And let us know how it goes.
MT