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89 350tbi fuel problem? Hesitation,power loss

S

swedester

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I have trouble with my 89 silverado 2500 pickup, its low on power, hesitates some and are terrible on gas, it ran fine when I got it, but after a while the Engine light started coming on as soon I started it, and the increased rpm at cold start also dissapered. This problem came and went, but now its permanent. Ive changed the fuelfilter, checked all wiring and today I took a complete tbi unit from my burb and put on, same problem oh, I also replaced the oxygensensor to a bosch unit with separate ground cable. I also checked the egr valve and the preload on the rockers, need help!
 
Man, sounds like your truck is doing all it can to get help, work with it. You got to find out what codes its setting when the check engine light comes on.

A reader would be nice, but since it uses older OBD1, it would not help much. Just get a paperclip, or any other short piece of solid wire, a pencil and paper, and grab the codes.
Once you get the codes, post them here, and we can give you some ideas.

I know the retrieval of codes has been discussed here many times, but I cannot find the exact instructions.
So, here is an external link.

http://www.obd-codes.com/faq/read-gm-2-digit-obd-codes-free.php

The light will flash all the two digit codes in order. First should be a 12, one flash, pause two flashes, repeated 3 times, then the other codes in the same way.
 
Hi, I had a '90 tbi Blazer, and also a '93 C-10 tbi that both lost power and ran very badly before not being able to start them at all. Both had the same problem, lack of proper fuel pressure due to a split hose inside the fuel tank. I think that the alcohol content in the new fuels are causing the hose to deteriorate. If you can, check your fuel pressure after checking codes, etc. My '90 only had 4 lbs but would still run. The split hose allows the fuel to spray inside the tank, instead of putting pressure on the outlet tube. Just replace the hose, and back on the road. Hope this helps.
 
4xcrazy said:
fuel pressure
Click to expand...
Oh, now I can see what you said... your avatar blinds me! :eek1:

I'd never argue fuel pressure, the ECM has no way to know what it is, but calculates everything off what it's supposed to be.

But he needs to find out what the Check Engine Light is first! The ECM does know when other things are wrong and it's telling him something is wrong.
 
42 is the EST module in the distributor, it is either bad or has a wiring issue. This code will also set if you disconnect bypass wire to set timing. But when cleared does not come back if module is good.
 
Changed the module, it runs fine now, but after driving a couple of minutes/miles, the engine light comes on, and I get code 44, should I try another oxygen sensor or is there something else I should try first?
 
Now were back to fuel pressure! I was afraid you had 2 issues, usually with code 42 you get code 45 O2 Rich!

I doubt it is the O2 sensor. But the O2 sensor is throwing a lean code, this is usually lack of fuel. So check fuel pressure, it could be a filter, pump, line, regulator, etc...

Could also be something like a sticky EGR or vacuum leak, but if idle is good? Then I'd still be on fuel pressure first.
 
Mine had all sorts of different codes pop up when my pump went out the first time. I'd replace the coded piece, then something else would come up.

O2 sensor was the main one though that always seemed to come back around, even after replacing it with new. Always a lean condition.
 
Old thread same story, I checked timing today and reset the memory by removing the batcable, now I need to know wich connection on the tb is the pressure side from the tank/pump, and what the fuelpressure should be.

/ Vince
 
It's been a while since I've messed with it, but IIRC, the passenger side line is pressure. If you look at your TBI, the pressure side goes into the fuel pressure regulator and takes the high path over top of the TBI. If pressure exceeds the regulator spring pressure (round-bottomed can under FPR), then the FPR diaphragm bleeds fuel back to tank.

TBI.jpg
 
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