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Old October 21st, 2012, 06:38 PM   #1
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Default 92 chevy tbi runs bad

92 chevy 2500 v-8 tbi the truck was running bad & stalling intermintantly so i put a new fuel pump in it and noticed the gas looked watered down so I drained the tank at the same time truck ran great till it rained for a week & it looked like water in the gas again so I drained fuel again ,then fixed sender/pump seal so no more water can get in & while I was messing with it I put new plugs ,wires ,cap & rotor and fuel & air filters the truck starts up & idles fine but when you rev it up it sounds like its bogging down Ive checked the fuel pressure its just under 15lbs when put inline& running & remains the same when reving it up & its bogging & 18 lbs when its dead headed into the guage.the gas coming out of the fuel line at the tbi is clean & looks good. the catilyic converter is gone replaced by a test pipe . the new pump was a cheep ebay pump but the pressure #s are within specs the timings is correct . no codes any Ideas ??of what to try next
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Old October 23rd, 2012, 02:03 AM   #2
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How does the spray pattern off the injectors look. Just a thought but some of the injectors had problems with the connection on top of them. Normally its a simple fix even if it just eliminates a doubt. With the engine off and air cleaner removed, unplug the connector on top of the injector and take a pick to the actual connector and tighten up the tabs that actually make the connection. I had the same problem in the past and this helped.
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Old October 23rd, 2012, 11:09 AM   #3
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always tripple check the ground wires at thermostat housing and block to frame, block to body etc. very crucial on this setup
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Old October 23rd, 2012, 11:19 AM   #4
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Needs a new distributor.
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Old October 23rd, 2012, 07:30 PM   #5
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my 88 did the same thing when the distributor was cracked and my plug wires wer drenched in oil due to a bad valve cover gasket
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Old October 28th, 2012, 09:51 AM   #6
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Couple maintance tips that I tend to do with a TBI when I first get it.

Pull your IAC and TPS and spray some carb cleaner in it. Push the spring on the iac a few times while spraying to clean out the carbon. Or just replace these as they are very cheap parts.
Pull the vacume lines CAREFULLY by working them back and forth as the cheap azz plastic tends to crack easily. Blow the oil out of the lines with a air nozzle then put one finger over one end while blowing into the other to check for leaks.

The TBI is extremly simple. They do not mind sitting for a few years like carb's do. This is the easiest carb you will ever rebuild. The only real thing to remember is to compress the fuel regulatior spring. A rebuild kit with everything but the injectors is like $50 or so from napa. It is easy to tell if you have a ripped regualtior by giving the carb a reach around and seeing if the seal is wet at the 4 bolts holding the regulatior in. There may also be gas stains on the intake.

I Have never replaced a injectior on a TBI unit and have drove these trucks into the 300's before something went out like the transmision or internal engine that I simply did not want to mess with over getting another $800 truck for. I doubt it is your injectior. The filter after the injectiors or seals around the filter all will be within the cheap kit.

There is a electronic egr on all first gen tbi trucks. It is on the passenger side of the carb and has a bracket that extends it above the Valve cover. There is a foam insert(on most not all) covered by a small plastic cover and I believe there is 2 or 3 hoses on the back of the unit. The lines and foam clog over time.
When bad it will cause stalling, very low throttle responce for a long while then will suddenly engauge, and NO codes. It reads as a o2 sensor. I have fixed 4 trucks where this little sob was the issue and it never gives a code. I bought 3 of them because of it. Want to sell me your truck. JK
This is a bit expensive sensor(the most expensive actually at around $150)and is something you actually need to get from the dealership for some reason. I have been on the road for 5 years now maybe things have changed.
To check it clean out the lines going to it, then simply unplug it with the key off. Start the truck and expect the same results. You might even get a o2 sensor fault. Well you will anyway with the delete.

Another thing to check is the EGR canister, Fuel retuen or whatever you want to call it. That vapor ball thing that people plug or remove. But that is more of a maintance thing to give you better starting.

Check your timing, cap, and give it a general tune up.

But I either expect it is the EGR or the lines going to it. Replace the cheap maintance junk first cause it is just good practice. But if you can not figure it out consider the EGR sensor as a last resort. I don't want you dumping cash on this sensor if it is something simple like your timing being off.
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Old October 28th, 2012, 10:11 AM   #7
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thanks for the replies it just seems odd that it did this, then i changed gas & then the pump & it worked fine until it got more water in the fuel again(that problem is fixed now ) I'm going to try taking the tbi off. apart & clean it Ive got a few other tbi's laying around but Im not sure if they are the same but I can probably get my hands on a different tbi(before I buy too many parts )to see if the problem changes or hopefully goes away
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