Another Rough Running Question

[Conundrum]

My 91 suburban hadnt run since before thanksgiving. It's been getting nicer outside lately so I decided to work on it today. I changed the plugs and the tempurature control sensor and both battery cables. My dad and I got it started with a jump start and I took it for a little drive and it did run better but it still hass a hesitation to it. So i'm wondering if it my thing to check would be the timing or the injectors? The injectors seem to be working fine, spraying gas like I think they should. Any ideas?

[73chevyman]

so its a tbi check the mass air sensor if it has one also could be a bad O2 sensor been awhile since i worked on one of those lol.. need more info though.

[Conundrum]

It had a replacement crate installed about 44,000 miles ago. The PO said that it ran fine until the fuel pump went out and she had it replaced. It idles rough when you first start it but it will smooth out and when you rev it up it sounds fine, nice and smooth. But as soon as up put it in gear and try to drive it, it has a hesitation and sounds like its misfiring. I have replaced the tps, cap and rotor, plugs, wires, battery cables and fuel filter. Have been trying to figure this thing out since last april when I bought it. I'm to the point of either going to a mechanic or swapping to a carb.

[Conundrum]

??

[paruszkiewicz]

did you check the fuel pump maybe she got a bad one i had a 91 astro van sounds like yours was doing the some thing. i tried everything , then took it it in and it was the fuel pump i was dumbfounded. it was sprying what i thought was good but it didnt have enough pressure. Just a thought

[ChopperDave]

check for vacum leaks yet?

[Conundrum]

Yeah, I have always thought it could be the fuel pump cause I know you can always get a bad part even if it's new (not saying the shop she took it to even used a new pump) and I know there are something like 3 different sizes of fuel tanks for the suburbans. Do they all use the same pump? Is the pickup seperate from the pump itself? If they are different for each size tank, how can I tell what size mine is without filling it up with gas?

I haven't checked for any vacuum leaks yet because I haven't heard any, but i'll get that out today after work.
Think I will pick up a throttle body gasket while i'm at it.

[73chevyman]

yea if it started since the fuel pump was installed then it could be that. could be a leak around the intake spray some starting fluid around it and if you have a leak the motor will race good luck

[Conundrum]

Thanks for all the advice guys, I will let you all know how it turns out.