91' Chevy c-1500 sport

[Spector1333]

Hey Fellas,
I need some help with this one. I just bought this truck to use as a work vehicle. Think I may of got suckered. The truck will only start if you barely give it any throttle at all. It then will not idle. It will die if you attempt to give it any more thottle. So far I have replaced Mapp sensor, idle air control valve, tps. I also visually checked the spray of the TBI injectors and it looks great. I removed the EGR and cleaned the pintle and carbon from the intake. None of these things have helped. I am kinda going crazy working on this thing and feel like I'm chasing my tail. Any idea?

[MT-2500]

Start with checking for codes and check fuel pressure and fuel filter.
Also how is the rest of the tune up? Like plugs and dist cap and wires air filter?
Post back any codes no.
MT

[Spector1333]

Originally Posted by MT-2500

Start with checking for codes and check fuel pressure and fuel filter.
Also how is the rest of the tune up? Like plugs and dist cap and wires air filter?
Post back any codes no.
MT

I'm not exactly sure how to check codes but I can say that I have inspected all of the ignition parts and they all have been recently replaced as I think the previous owner was having this problem already and started replacing simple things first. I did check fuel filter and pump. Pressure is 8 pounds. Injectors spray very good. No drips. Thanks for the reply. Any help is welcome at this point.

[79403ta]

have you checked for vacuum leaks ?? this would cause an erratic idle....have you checked the timming i have seen the hold down for the distributor work itself loose over time check this also it has got to be ignition or fuel...how many miles are on the truck ??

[MT-2500]

Fuel pressure specs are 9-13 lbs pressure for it.
You are a little low.
To check for codes ground A and B together on your Diagnostic connecter.
MT

[Spector1333]

Originally Posted by MT-2500

Fuel pressure specs are 9-13 lbs pressure for it.
You are a little low.
To check for codes ground A and B together on your Diagnostic connecter.
MT

After working on truck all afternoon have made new discoveries. Code showed 22. TPS sensor . I did not replace it yet. I unplugged the vaccum hose from back of throttlebody and capped it off. Now the truck will start and idle but when I drive it....it has horrible hesitation. The vaccum hose ran to a sensor above the EGR. I am not familiar with what that is . Any ideas?

[MT-2500]

Hook everything back up.
Clear codes and see if code returns.
It sounds like you need a little professional help on this one.
MT

[Spector1333]

Originally Posted by MT-2500

Hook everything back up.
Clear codes and see if code returns.
It sounds like you need a little professional help on this one.
MT

Just wanted to post an update. Put truck in shop this morning. Problem turned out to be a faulty idle air control valve. I had bought and installed one from napa. Valve didn't work. Counts were 155 and would not come down at all. Fuel pressure is still going up and down from 6 to 10 pounds so I will be changing out the fuel pump. Truck is running just wanted to post results in case anyone else has this same trouble. Thanks to all who tried to help.

[MT-2500]

Thanks for letting us know how it is going.
Sounds like they are getting it figured out for you.
Good luck MT