1987 TBI 454 Suburban... It Runs! Kinda.

MrSony

MrSony

Comic Book Super Hero
Nov 15, 2014
4,597
2,868
113
Des Moines, Iowa
#1
Non g body, but I bought a pretty nice suburban for $1500, non running. Guy said the timing chain was bad, but the distrubutor moves at a healthy clip, there is no delay/slack when moving it by hand. I have moved the distributor as far as i can in both directions, I have swapped plug wires at the cap clockwise 1 and 2 terminals, and counter clockwise 1 and 2 terminals from the original position. timing is set static at 4*btdc like it says on the sticker on the shroud. it has fuel, it actively squirts as it's trying to fire. it has spark. it cranks over at a pretty healthy clip. sometimes it will go pupupupuh like it's trying to run, but it won't.

any help is appreciated, idk how many of you mess with TBI stuff, but it's all there and i kinda don't want to spend $600 right now converting to carb.
 
spidereyes455

spidereyes455

Master Mechanic
Mar 6, 2013
281
232
43
Northeastern PA
#2
Start with the basics. Are the plugs any good? Does it have good compression? Try re timing the distributor bring #1 up on tdc on compression and see if the rotor is pointing to #1 on the cap. Mabey the chain jumped a tooth.
 
Turbolq4

Turbolq4

Royal Smart Person
Sep 25, 2017
1,089
1,881
113
Nampa Idaho
#4
Pretty much can't effectively convert these to carb without alot of parts. Check the ignition module. Also verify timing/ TDC
 
M

Max Headroom

Greasemonkey
Sep 8, 2011
124
50
28
#5
All good advice above. What size is the engine?
A couple of other things you can look at:
  • If he said the timing chain was bad, he may have pulled the distributor. If he put it back in one or even two teeth out of position, the engine would put - put - put, like you said it is doing
  • Another thing it could be, if he pulled the distributor, is the distributor is 180 degrees out of phase. Roll it around to where No1 should be at TDC and locate the rotor position and make sure it is pointed at the right spot.
  • Check the wear on both the rotor and the contacts in the distributor cap. I bought a car once for parts because it wouldn't start. Got to looking and the dist. cap contacts were so corroded they wouldn't pass enough voltage to fire the air/fuel. Turns out the cap had a crack and water kept getting inside. Put a new cap and rotor and drove the car for several months before someone wanted it more than I did.
If it is a stock engine, even if the distributor is out of position, I don't think you can bend anything on a piston. You might try starting the engine on a shot of ether. This will eliminate a lot of potential causes, if it starts. I wouldn't keep it running on the ether, just see if it will "fire off" as they say down here in the Deep South.
Good luck
 
MrSony

MrSony

Comic Book Super Hero
Nov 15, 2014
4,597
2,868
113
Des Moines, Iowa
#6
It's a 454, stock two barrel TBI, everything is there and everything is stock. I did confirm it has compression. Plugs are good. I don't like the looks of the wires, those will be changed. I was planning on getting tune up stuff (was hoping it was just an HEI engine... damn) anyway, so I guess off to the store I go.
 
spicercars

spicercars

Apprentice
Jan 7, 2019
99
50
18
Saginaw MN
#7
As others have mentioned check number 1 tdc with the distributor to make sure the plugs are firing at the right time.
 
MrSony

MrSony

Comic Book Super Hero
Nov 15, 2014
4,597
2,868
113
Des Moines, Iowa
#8
It's 32 years old, it either has 49,*** on it of mostly highway driving, and gravel/mud roads (was used as a ragbrai truck... team tallywhacker windows are in the back...), or 149,***. Either way, to eliminate as many variables as possible, I'm going to be replacing basically everything except the throttle body and distributor themselves.
As others have mentioned check number 1 tdc with the distributor to make sure the plugs are firing at the right time.
I have done that. I will recheck while I'm replacing things.

the P/O said the timing chain was bad, and there was noticable delay from moving the engine to moving the distributor, but I have turned the engine both ways by hand and with the starter (the only way it turns obviously), and I see no indication that the timing chain is bad. And from what I've read, the R2500 suburbans had a steel timing gear, so it can really only either stretch, or explode. And since the dist is moving, the valvetrain is moving, I'd say it would be fine enough to at least get it to run.
 
TURNA

TURNA

Geezer
Jul 24, 2009
7,010
9,247
113
Socialist NY
#9
VATS? Crank sensor? are the plugs wet? engine light on?

What is the fuel pressure? fuel filter clogged?

If the coolant sensor is bad it will not start.

And there is a **** load more tooooooooooo
 
TURNA

TURNA

Geezer
Jul 24, 2009
7,010
9,247
113
Socialist NY
#10
Oh and those little cap distributors they put in those are junk!!!!
 

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