Tbi Hesitating/ Very Weak? Help

[eddinger]

Hello everyone,

 

 

I am so glad I found this site, I need help finding my problem. Quick background about my skill, I have none, but I'm learning. I recently bought a 1993 Suburban 2500 off an old man for a great price. Bought it to pull a camper that I traded my motorcycle for. The Burb has a 454 in it, 2 wheel drive. Thanks to help from my freinds and a lot of reading I have started to tune it up myself. So far I have replaced- plugs, wires, fuel filter, air & oil filters, PCV, serpintine belt & tensioner. I am about to change the brakes tonight.

 

Now, here's my problem, when I give it a lot of gas/ throttle, it sounds like it wants to go but it won't. I just cleaned the top of the throttle body with carb cleaner and put it Seafoam to hopefully clear any carbon build up. If that doesn't work I was wondering what it might be? I have been told the fuel pump is bad, injectors on one side might be clogged, need to take apart the TBI and give it a good cleaning. Has anyone had a similar problem? I am more than willing to go through the TBI, just don't know what, if any, parts I should replace when I do. I hope it's not the fuel pump but I fear it might be. I just thoght that they either worked or they didn't, can they start to fail but still send enoughv gas for me to drive it with slow pick up?

 

I also converted the R12 to R134a and it is working great, saved a lot of money doing that myself, I proud of that little accomplishment.

[jro909]

if the pump and injectors are clogged man, theres your problem....if the pump is too weak to feed enough fuel to power the engine its just going to be a turtle, if the injectors are clogged then its pretty much the same problem...not enough fuel to power the motor...hope that helps

[eddinger]

Pulled my injectors off last night, how do I know if they're clogged? One looks like it has a very tiny tear in the screen, don't know if that's a problem. Should I go ahead and replace my fuel pressure regulator?

[[email protected]]

You crank it up with the air cleaner off and look at the stream coming out of the injectors, it should be cone shaped and not a stream and, not none coming out. The usual cause of the hesitation on tbi are dirty throttle bodies, bad injectors (you usually tap then while running and fix them temporarily), weak fuel pump or crack in rubber hose in fuel tank, or bad coolant temp sensor. This hesitation will foul the plugs in a heartbeat so make sure they're still good.

[hockeypro1411]

I'd bet it's a bad fuel pump or injectors.

[98 Z71 SLT]

Classic complaint of a dying fuel pump---truck does run, but hesitant, hi-rev shifts

 

Put a fuel pump in it...betcha that solves your problem

[eddinger]

Got an appointment to replace the pump Monday. One of the injectors isn't working properly. Do I replace the one, or should I go ahead and get both?

[Willshire]

Got an appointment to replace the pump Monday. One of the injectors isn't working properly. Do I replace the one, or should I go ahead and get both?

 

You can buy stock injectors if you want but, i just rebuilt a 350 tbi and i got my injectors from tbiparts on ebay Sean Rondeau i think is the guys name. He sent me a set of flow matched 68lb injectors for 200 bucks. Very knowledgable. i believe the 454 was 80lb injectors and are hard to come buy but shoot him an email and he may be able to help. I sold the truck out of desparation and lost a boatload. And if you want it chipped, tbichips. Also very helpful. Hope this helps. Oh, and i put an edelbrock hi-flow on my truck it was like $100 from summit. i believe on the 93 only the pump needs replacing not the whole sending unit

[Mark Leigh]

Got an appointment to replace the pump Monday. One of the injectors isn't working properly. Do I replace the one, or should I go ahead and get both?

 

You can buy stock injectors if you want but, i just rebuilt a 350 tbi and i got my injectors from tbiparts on ebay Sean Rondeau i think is the guys name. He sent me a set of flow matched 68lb injectors for 200 bucks. Very knowledgable. i believe the 454 was 80lb injectors and are hard to come buy but shoot him an email and he may be able to help. I sold the truck out of desparation and lost a boatload. And if you want it chipped, tbichips. Also very helpful. Hope this helps. Oh, and i put an edelbrock hi-flow on my truck it was like $100 from summit. i believe on the 93 only the pump needs replacing not the whole sending unit

 

You might take a good look at the wires leading to the injectors, especially if they look like they have been damaged from a backfire condition,

[Willshire]

Got an appointment to replace the pump Monday. One of the injectors isn't working properly. Do I replace the one, or should I go ahead and get both?

 

You can buy stock injectors if you want but, i just rebuilt a 350 tbi and i got my injectors from tbiparts on ebay Sean Rondeau i think is the guys name. He sent me a set of flow matched 68lb injectors for 200 bucks. Very knowledgable. i believe the 454 was 80lb injectors and are hard to come buy but shoot him an email and he may be able to help. I sold the truck out of desparation and lost a boatload. And if you want it chipped, tbichips. Also very helpful. Hope this helps. Oh, and i put an edelbrock hi-flow on my truck it was like $100 from summit. i believe on the 93 only the pump needs replacing not the whole sending unit

 

You might take a good look at the wires leading to the injectors, especially if they look like they have been damaged from a backfire condition,

 

 

 

That too!

[eddinger]

Well, I just put in the new injectors( Delphi ) and it now sounds worse than before. I don't know what size injectors were in there but I am pretty sure that the ones I put in run 90lbs/hr. So, I am taking it in this Monday to have the fuel pump replaced. I hope that's it and not something wrong with the injectors. I will remove them and reinstall again tonight when I get home just to make sure I didn't do something wrong the first time.

[eddinger]

well, here's how it all panned out. I got the fuel pump replaced. Thank goodness I had a garage do it, they ran into a couple problems. First, when they removed the old pump it had blue silicone in and around it. He had to remove it from inside the gas tank and fuel line. Once that was done when they tried to test drive it the idle was jumping all around. Come to find out that the new injectors that I got off ebay were incorrect. They were in the right box, but the injectors were not. So we put the old ones back in and now everything is running great. Drove it down to the Outer Banks of North Carolina without a single problem. As a matter of fact I'm here right now posting this message waiting for my family to wake up so we can ride out to the Hatteras Lighthouse. Thank you all for all your help with my problem. I hope I can do the same for some one down the road.

 

Oh, and the best part, the mechanic didn't charge me any extra for the extra days work he put into it trying to get it right. He even cleaned out the carbon build up in the intake free of charge.