TBI Throttle Body Tear Down and Rebuild.
- Thread starter Swims350
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
austinado16
Full Access Member
- Joined
- May 25, 2012
- Posts
- 611
- Reaction score
- 222
- Location
- Central Coast, CA
- First Name
- Todd
- Truck Year
- 1990 w/307k miles on the clock
- Truck Model
- GMC V1500 Suburban SLE
- Engine Size
- 5.7L TBI/4L60/3.42's
The drops might be my issue. I haven't snap-shotted it with a timing light, but have stuck my face in there and watched (recently) and at idle, I was sort of shocked at the amount of wet fuel "dropletting" on the throttle plates at idle. I even ran a can of SeaFoam through it after that.....no improvement.
I installed the Edelbrock TBI manifold about 8mos ago, but had a fine cold (and hot) idle following that.
I installed the Edelbrock TBI manifold about 8mos ago, but had a fine cold (and hot) idle following that.
Jims86
Full Access Member
- Joined
- Aug 3, 2010
- Posts
- 5,492
- Reaction score
- 135
- Location
- Patterson,Ca
- First Name
- Jim
- Truck Year
- 1986
- Truck Model
- K10 Suburban Silverado
- Engine Size
- 5.7 TBI
As a starting point,
I usually set the throttle plates to where the top surfaces are right at the bottom of the ported vac holes in the barrels. a lot of them end up set that way from the factory, and you may find that its just right, and not have to adjust it at all.
Warm it up to operating temp.
Ground A and B like you are going to pull codes. Turn on the key, wait 30 seconds. look into the iac passage, make sure you see the pintle. , then unplug the elec connector.
pull the jumper from diag. connector.
start the engine, and let it run about 20 seconds to get passed the open loop timer.
in drive, set the minimum idle at 525 rpm+/- 25
shuter down, unplug the battery neg for 15 seconds, and plug the IAC back in. it may start with a real low idle the first 3 or 4 times, but thats it.
may idle a little crappy for a bit until the ecm re learns everything, but drive her around at 35 mph for about 1/2 an hour, with some stops, maybe let it sit and idle for a few minutes in drive a few times....but that should do it.
Jims86
Full Access Member
- Joined
- Aug 3, 2010
- Posts
- 5,492
- Reaction score
- 135
- Location
- Patterson,Ca
- First Name
- Jim
- Truck Year
- 1986
- Truck Model
- K10 Suburban Silverado
- Engine Size
- 5.7 TBI
Yeah, they may need a good cleaning. seeing fuel on the plates is normal...the real atomizing action starts when it squeezes past the plates at high velocity.
Last edited:
Swims350
Full Access Member
- Joined
- Jul 30, 2010
- Posts
- 4,352
- Reaction score
- 812
- Location
- Logan WV
- First Name
- Chris
- Truck Year
- 1983
- Truck Model
- K10
- Engine Size
- none
I reinstalled mine yesterday, and wired it up, hooked it up etc. Only thing I left was the fuel feed line and IAC. I'm going to clean that line out before hooking it up and then reset the IAC.
Jims86
Full Access Member
- Joined
- Aug 3, 2010
- Posts
- 5,492
- Reaction score
- 135
- Location
- Patterson,Ca
- First Name
- Jim
- Truck Year
- 1986
- Truck Model
- K10 Suburban Silverado
- Engine Size
- 5.7 TBI
Cool! Cant wait!
Swims350
Full Access Member
- Joined
- Jul 30, 2010
- Posts
- 4,352
- Reaction score
- 812
- Location
- Logan WV
- First Name
- Chris
- Truck Year
- 1983
- Truck Model
- K10
- Engine Size
- none
well might want to delete this sticky because it didn't work.
NOW the stupid FPR is dumping gas out around it.
truck turns on, no leaks, on and off several times, leave the key on, no leaks.
start it up, and it gets leaks.
I tore that back apart saw nothing wrong, put it back on, same thing, key on and off several times, no leaks, fire it up for a sec or two, no leak. Fire it up and let it run 30 seconds or so and check and it's wet.
The first time I removed the top the entire gasket was wet with gas, the one around the injectors.
I have no clue hat's wrong with this heap a turd. I'm going to see if the regualtor cover is bent/warped and maybe see if I can get a diaprham new and try it.
Also the thing idles wayyyy too high, it's like 2500 rpms or more. I don't have any vacuum leaks that I know of either. I'll have to check it out tomorrow, if it's not something simple be prepared for a new thread, entitled how to convert tbi CRAP to carb.
NOW the stupid FPR is dumping gas out around it.
truck turns on, no leaks, on and off several times, leave the key on, no leaks.
start it up, and it gets leaks.
I tore that back apart saw nothing wrong, put it back on, same thing, key on and off several times, no leaks, fire it up for a sec or two, no leak. Fire it up and let it run 30 seconds or so and check and it's wet.
The first time I removed the top the entire gasket was wet with gas, the one around the injectors.
I have no clue hat's wrong with this heap a turd. I'm going to see if the regualtor cover is bent/warped and maybe see if I can get a diaprham new and try it.
Also the thing idles wayyyy too high, it's like 2500 rpms or more. I don't have any vacuum leaks that I know of either. I'll have to check it out tomorrow, if it's not something simple be prepared for a new thread, entitled how to convert tbi CRAP to carb.
crazy4offroad
Equal Opportunity Destroyer
- Joined
- Jul 30, 2010
- Posts
- 8,479
- Reaction score
- 1,109
- Location
- West BY-GOD Virginia
- First Name
- Curt
- Truck Year
- 1979
- Truck Model
- K-10
- Engine Size
- 350/SM465/NP205
I'm sure Jim will be here soon to help. Is it possible you got the wrong fuel pump? I know TBI has a little higher pressure than carb, and I might not know wtf I'm talking about but isnt TPI/MPFI even higher pressure? Would it be enough to screw with the regulator?
Jims86
Full Access Member
- Joined
- Aug 3, 2010
- Posts
- 5,492
- Reaction score
- 135
- Location
- Patterson,Ca
- First Name
- Jim
- Truck Year
- 1986
- Truck Model
- K10 Suburban Silverado
- Engine Size
- 5.7 TBI
Your right on track with checking the diaphram, and sometimes the flange on the fpr get bent, but I would inspect the whole thing. It just needs to be snugged down.
Ground A and B for 30 seconds to make sure the IAC is closing all the way. if you are 100% sure you have no vac leaks, the IAC is the only place where air can get by to make it run that high. The for regulator leak could cause it too, the ecm sees the extra fuel, and opens the IAC to compensate....so, the fpr leak may be the whole problem. Dont fret about this, I have some ****** up fprs every now and then...and i have been doing them for better than 20 years.
Ground A and B for 30 seconds to make sure the IAC is closing all the way. if you are 100% sure you have no vac leaks, the IAC is the only place where air can get by to make it run that high. The for regulator leak could cause it too, the ecm sees the extra fuel, and opens the IAC to compensate....so, the fpr leak may be the whole problem. Dont fret about this, I have some ****** up fprs every now and then...and i have been doing them for better than 20 years.
Swims350
Full Access Member
- Joined
- Jul 30, 2010
- Posts
- 4,352
- Reaction score
- 812
- Location
- Logan WV
- First Name
- Chris
- Truck Year
- 1983
- Truck Model
- K10
- Engine Size
- none
parts stores are dumb.
they want $40 for a fpr diaprham kit, and I paid $33 for a rebuild kit. COME ON!!!!!!!!!!
if I have to buy another I'll be buying a kit and not the stupid fpr diaprham itself.
they want $40 for a fpr diaprham kit, and I paid $33 for a rebuild kit. COME ON!!!!!!!!!!
if I have to buy another I'll be buying a kit and not the stupid fpr diaprham itself.
- Joined
- Dec 7, 2010
- Posts
- 24,772
- Reaction score
- 6,636
- Location
- Southeast PA
- First Name
- Paw Paw
- Truck Year
- 2007
- Truck Model
- Chevrolet Tahoe LT
- Engine Size
- 5.3, 4WD
I know you are busting your ass on this and it's hot as hell out, don't let this stop you now Chris. Just take a break and we will try and help you figure this out.
I have been beating my head against the wall also to get my ECM system kosher. It's a bitch, and being broke doesn't help the least bit.
Didn't you say something earlier here about tampering with the sealed idle screw?
I have been beating my head against the wall also to get my ECM system kosher. It's a bitch, and being broke doesn't help the least bit.
Didn't you say something earlier here about tampering with the sealed idle screw?
Jims86
Full Access Member
- Joined
- Aug 3, 2010
- Posts
- 5,492
- Reaction score
- 135
- Location
- Patterson,Ca
- First Name
- Jim
- Truck Year
- 1986
- Truck Model
- K10 Suburban Silverado
- Engine Size
- 5.7 TBI
I know you are busting your ass on this and it's hot as hell out, don't let this stop you now Chris. Just take a break and we will try and help you figure this out.
I have been beating my head against the wall also to get my ECM system kosher. It's a bitch, and being broke doesn't help the least bit.
Didn't you say something earlier here about tampering with the sealed idle screw?
If he still has the high idle after reinstalling the fpr, its something really simple, and right in front of him. I dont think he did anything else to the engine.
Swims350
Full Access Member
- Joined
- Jul 30, 2010
- Posts
- 4,352
- Reaction score
- 812
- Location
- Logan WV
- First Name
- Chris
- Truck Year
- 1983
- Truck Model
- K10
- Engine Size
- none
nope done nothing but removed the cap from the idle screw. I can fix that easy enough though. I haven't reset the IAc either so that's one thing. My main issue the the leak. once that's fixed I'll handle the rest.
Swims350
Full Access Member
- Joined
- Jul 30, 2010
- Posts
- 4,352
- Reaction score
- 812
- Location
- Logan WV
- First Name
- Chris
- Truck Year
- 1983
- Truck Model
- K10
- Engine Size
- none
leak seems to be fixed. it runs, idles and such. I'm letting it reset right now on the IAC. going to hook it up and let it run some. I can't drive it yet, have to bleed the brakes and set the toe on it.
Similar threads
