sbc starting problems

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donnie12

10 Year 15 Year
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Mar 27, 2010
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i just finished my tbi sbc swap i go to start it and it dosent start, it has fuel preasure it has spark .
i spray starting fluid in it and it starts and runs fine but when i dont use starting fluid it dosent start ....theres two signal wires that are spose to go to the started solinoid a red one and a purple one i have the purple one on the small terminal to the right of the two big ones i have the red one on the top big terminal if i put it on the bottem one it blows the fuse



in the pic the red wire is off because i was trying things
yota wire.webp
 
If it fires with the starting fluid then you have a fuel problem. possibly a fuel pressure issue. Are you sure you have enough fuel pressure for the TBI?
 
if its anything like S10 TBI the injector gets its "pulse" from the cam sensor (in the dist)

are you sure its getting the correct (or any) signal from the distributer?

if you have pressure it should be getting to the injector...to check you can pull a injector out and crank for a second to make sure its going to there...
 
i have 9-11 pounds of fuel pressure

i can crank it and crank it and dosent fire it sounds like it wants to but never dose

to set the base timing ?? it says dissconnect the set timing connector , once you have this disconnected start the engine and set the base timing to 0 degrees <how do i set it to 0 degrees
 
Uhhhhhhh I know that the stock Toyota fuel injection system wants fuel pressure somewhere around 40 psi... I'm not up on the SBC, but I would imagine that any fuel injector would want more than 10 psi.... Carbs only take 3-5 psi.

If it won't run, you will just have to check the timing while someone cranks it over (hook the timing gun up like normal). If the timing is way off it will not want to start or run. Have you had the distributor out in this swap? Could it be off a tooth?
 
My first thought is that you have a fuel delivery issue. If it starts with starting fluid then it is obviously fuel. I suspect your timing might be off a bit but if it starts with starting fluid it should start with fuel............so you aren't getting fuel.

See if you can get it to run a bit with the starting fluid, long enough to get a handle on your timing. Good luck and happy motoring
 
That's definitely your problem. You need about 50 psi of fuel pressure for a fuel injected sbc. Try a 12v in line pump.

As a general rule of thumb a carbed v8 manual fuel pump puts out about 8-10 psi. In tank fuel injection pumps put out 40-60 psi.

Did you put fuel injection on a motor that was originally carbed and try to re-use the block mounted pump or something?
 
TBI usually needs about 20 PSI IIRC, it's a lower-pressure system than TPI or MPFI.
Are you running a return line from the unit to the tank? That alone can cause flooding.
 
the dizzy never coming off doesn't mean a thing.
An engine swap involves alot of jockeying and the cap could have been bumped off-time, even slightly.

I'm with Toyminator, get a better fuel pump. Is there a pump relay setup? That can be critical because in FI the pump isn't constant, like a carb, but is "paced" as needed, depending on the engine's fuel usage.

Good luck!
 
THIS IS NOT A TIMING ISSUE!!:censor:

if the timing was off that much starting fluid wouldnt do anything

1. you have pressure
2. you have spark



are the injectors getting a pulse/signal?
do you have an EFI distributer?
 
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I wasn't suggesting a timing issue, I meant to say that it's foolish to assume anything on that engine's surface wasn't at all disturbed in the process of the swap. I realize full well I did not articulate it well.

As to fuel pressure, 9-11 PSI is a leak compared to what TBI needs. Check the fuel pump, and fuel pump relay. Without the relay, the pump won't know when to run, like at start.

How are the wires? are you getting a clean 12 volts into the ignition system?
Have you checked for error codes?

Have you made an animal sacrifice for atonement in creating a Chevota?
 
My money's on not getting a signal to the injectors or a lack of pressure. Regardless, it is something with the tbi. Put an inline push-put on it or check the fuel management system for pinched or cut wires. Make sure that the contacts inside of connections are where they should be!
 
raevenzero said:
... the contacts inside of connections ...
Click to expand...

X10!
Those can get really dirty, grease can get into them during the move, or they can get smashed.
Also, is the TBI harness grafted into the Toyota harness? If so, did you factor in that Toy electrical is negative switched?
 
I just had to troubleshoot a dead cylinder due to a connector that had a contact that would push up into the plastic when you locked it in. Therefore, the connection would be intermittent.
 
Makes Sense, I've seen these problems before. The contacts in TBI injectors are really tall, and prone to bending, last time I tinkered with TBI I learned that the plugs would bend these during removal. Bent contacts meant intermittent injection, and a non-rebuildable injector.
I doubt this specific scenario is the case here, but I have a feeling connectors in general may indeed be the cause.
FWIW GM connectors have always pissed me off, they're too intricate to mate together by hand without visibility, (like if the cable is inside a dash, and your hands are big) and too difficult to separate without breaking something(cheap plastic, too many clips, pins would yank out). I think that's what sold me on Toyota, is they seem to build their trucks like they expect, and encourage people to work on them.
 
Wiring

By looking at the harness in the pic it looks like this is from a standard shift not auto, the red wire should go to a junction block then to alt, purple goes to the clutch bypass switch on the GM then to power your ignition switch, the other wire would be your start wire from the switch. It has been a wile since I have seen one of these so I could be wrong, but this is from my memory not a diagram. I hope this helps.:cheers:

thanks
lee

P.S. go to advance and see if they have a noid light for the tbi for [loan] and check to see if you getting a pulse at the injector?
 
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maybe also take this to the 40-series board, TBI swaps are far more common there than here.
 
Or even the "4x4 & Vehicle Tech" section...
 
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