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1989 K5 350 TBI Fuel Issues?

Techson94

Techson94

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Deerfield beach
Before I posted this I searched for fuel issues and stumbles and I couldnt find anything that resembles my issues.

My son had this for daily driver for 2 years and I started rebuilding a year ago. Ran OK but had no power at all. Just figured it was 350 tbi.

Issues for last 3 years:
1) Engine would stumble and pop on accelleration after an hour of driving. I would pull over turn off and restart. It would be fine for another hour.
2) Had no passing power at all. Get up to speed but no accelleration.

New issues.
1) Stumbles and pops on accelleration.
2) Seems like a miss in idle now too.
3) Cheged fuel filter and no improvement.

I spent all my time making it look good and now I cant drive it. Looking for some help with plan of attack. I am planning to put a Vortec 5.7 in with a LT4 Cam. So I am beginning process by upgrading fuel system. I dont want to do engine now though.
1) Order and installing new sending unit and 1996 Vortec fuel pump.
2) Will be ordering 46mm bored tbi refurb from cprperformance.
3) Maybe new fuel lines.

I hate to learn the hard way but that seems to be the way I do it. Looking for feedback on if my plan to upgrade fuel system would be a good place to start or is there a better idea.

Thank you in advance.
 
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ANY MOD to the engine on tbi feed trucks / cars = custom burnt chip for the computer with data log info from your specific vehicle driving . this part i do know .
 
sweetk30 said:
ANY MOD to the engine on tbi feed trucks / cars = custom burnt chip for the computer with data log info from your specific vehicle driving . this part i do know .
Click to expand...

Thats what I understood as well. Mods to engine need chip. I didnt understand that to be same for fuel system.
 
Sounds like an ignition issue instead of a fuel issue. Something with the control module, pick-up coil, ignition coil, or distributor cap. Might want to check timing. Make sure it is set at 0 degrees (you can get away with as much as 4 degrees advance).
 
Last edited:
sweetk30 said:
ANY MOD to the engine on tbi feed trucks / cars = custom burnt chip for the computer with data log info from your specific vehicle driving . this part i do know .
Click to expand...

That is something I need to do with my truck. I have a small RV cam and bored out modified TBI on my 1991 TBI equipped truck. It runs OK with the stock chip, but it is not making all the power it could if I had a custom burned chip for it.
 
1-ton said:
Sounds like an ignition issue instead of a fuel issue. Something with the control module, pick-up coil, ignition coil, or distributor cap. Might want to check timing. Make sure it is set at 0 degrees advance (you can get away with as much as 4 degrees advance).
Click to expand...

Thanks I will check timing. I am not sure how to troubleshoot all those things you mentioned, but I need to learn anyway.
 
1-ton said:
That is something I need to do with my truck. I have a small RV cam and bored out modified TBI on my 1991 TBI equipped truck. It runs OK with the stock chip, but it is not making all the power it could if I had a custom burned chip for it.
Click to expand...

tbichips.com in my opinion has the best site on internet for tbi upgrade information.
 
jeff in co said:
Maybe new distributor too??
Click to expand...

I would agree.

Correctly installing a a new distributor for a "newbee" could be difficult. There are even (so called) professional mechanics out there that cannot install a distributor correctly (they would never admit it out of pride though). They will tell you "sure I can install it"...then give you back a vehicle with the distributor screwed so far around that the ignition coil power wires are stretched out to there maximum length.
 
I agree that there could be something up with the timing. I have to wonder if there is a problem with the knock sensor, or if it may be getting some improper signal from engine noise. I have talked with a couple of guys who feel that their TBI trucks pull timing out for no apparent reason.
I don't know how to go about checking the ignition control module for intermittent issues.
 
This is engine is very old and crusty. I think i will go ahead and replace distributor, pick up, and ignition coil. The control module has less than 2000 miles on it. It makes sense that its a timing issue since its getting fuel to tbi. I appreciate your feedback.

Any tricks to replacing these other than labeling wires and rotating engine to TDC?
 
dont even need to find tdc .

mark the dist housing to rotor tab in the 360* rotations its stoped at .

note the position of the dist body before you unclamp it .

pull dist up 3-4" and note how far the rotor tab moved .

lineup on new and drop in should almost be a drop in if you line up your marks . and noting it after you pull it up helps it drop in and on the oil pump drive shaft with no real prolems . if it wont drop use a screw driver with a looong reach to turn the oil pump shaft .

to set timming key off . unplug the brown wire down below the wiper area its a single weather pack connector just sticking out of the wire loom . fire it up set to 0* or some guys like up to 4* setting . lock down dist . key off . plug wire back in and refire to verify she is starting .
 
sweetk30 said:
dont even need to find tdc .

mark the dist housing to rotor tab in the 360* rotations its stoped at .

note the position of the dist body before you unclamp it .

pull dist up 3-4" and note how far the rotor tab moved .

lineup on new and drop in should almost be a drop in if you line up your marks . and noting it after you pull it up helps it drop in and on the oil pump drive shaft with no real prolems . if it wont drop use a screw driver with a looong reach to turn the oil pump shaft .

to set timming key off . unplug the brown wire down below the wiper area its a single weather pack connector just sticking out of the wire loom . fire it up set to 0* or some guys like up to 4* setting . lock down dist . key off . plug wire back in and refire to verify she is starting .[/QUOTE
Click to expand...
 
sweetk30 said:
dont even need to find tdc .

mark the dist housing to rotor tab in the 360* rotations its stoped at .

note the position of the dist body before you unclamp it .

pull dist up 3-4" and note how far the rotor tab moved .

lineup on new and drop in should almost be a drop in if you line up your marks . and noting it after you pull it up helps it drop in and on the oil pump drive shaft with no real prolems . if it wont drop use a screw driver with a looong reach to turn the oil pump shaft .

to set timming key off . unplug the brown wire down below the wiper area its a single weather pack connector just sticking out of the wire loom . fire it up set to 0* or some guys like up to 4* setting . lock down dist . key off . plug wire back in and refire to verify she is starting .
Click to expand...



Again I really appreciate the help.
 
The first thing to do is replace EVERY sensor with a new quality sensor. You have to do this before going any further.

My 92 vette ran awful and kept going into limp home because of super lean conditions. Crazy part it that it was so rich you could not stand behind the car. Replaced O2 sensors and it gained at least 100 hp and passed emissions with flying colors.

Had a 96 TA that had horrible transmission problems..... or did it? Sold it and new owner says that a throttle position sensor fixed the tranny problems. Go figure.
 
@Techson94

I read your original post. It sounds like it was a progressive issue? Used to be a warmed up and running problem and now its pretty much immediately?

Does your CEL work?
If so, does it come on after cruising at a steady speed or long deceleration (like going downhill)? If yes than skip the next question.

Automatic or manual?
If auto, does it downshift on full throttle?

Do you know how to do a cylinder leakage or compression test? Disconnect your crankcase breather from the aircleaner housing and direct it outside the engine bay. Does it pulse smoke at idle?
 
Oh yeah, and dont waste your money on ignition parts until you have a working CEL if it doesn't work currently.
 
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