SBC TBI troubleshooting

[Trollhole]

Even with the dizzy 180 out you should have some sort of combustion. Correct? A pop, a poof, or a bang?

This would at least get us on the right track.

Question.

Does your ECU know your trying to start the motor. You have the enrichment wire connected?

Does your ECU know your in Park or Neutral? Was your ecu out of a vehicle with an auto or manual transmission?

It won't start if you don't have those wires connected correctly.

Dizzy doesn't care where the body is pointing as long as the rotor is pointing toward #1 plug at TDC combustion.

 

[kblack77]

You asked me about the brown/white wire...no you will not need to put engine back on tdc as long as you've already done this along with putting rotor on correct spot. Disconect that wire with power off once engine starts and warms up thats when I would try and put timing around 4-6degrees btdc which would be ccw rotation. You need to have timing marks..mine didn't I had to add them. once you have that stop engine and reconnect wire. disconnect battery to clear number 42 code....then test drive, if you can get your hands on a hand held scanner you will want to go for a drive and have someone watch the knock sensor...you will need to search for what will be a proper reading...I haven't done that step yet.

also howell performance was a great help for me...they use stock gm componets!!!

Note when I was trying to starts and I could tell It was trying I had to open the throttle...Now that the engine has started, I do not have to do that any more it fires right up!

Also look into the fact that you have parts from diffrent cars, I think i remember you have to becarfull when doing that...just google tbi troobleshooting

 

[nicholastheczar]

I've had one little bang that sounded like the engine was going to try to start, but it was quick and then it was gone.

ECU was out of a auto, 88 chevy suburban w/ 700R4 I believe. I have a 700R4 in my 40.

Which wire is the enrichment wire? I have a painless wiring harness. I'm at work and don't have my vehicle or booklet w/ me. If I remember correctly, I have my vehicle speed sensor wire and my park / neutral indicator switch wired together which is what my painless wiring harness calls for.

Even with the dizzy 180 out you should have some sort of combustion. Correct? A pop, a poof, or a bang?

This would at least get us on the right track.

Question.

Does your ECU know your trying to start the motor. You have the enrichment wire connected?

Does your ECU know your in Park or Neutral? Was your ecu out of a vehicle with an auto or manual transmission?

It won't start if you don't have those wires connected correctly.

Dizzy doesn't care where the body is pointing as long as the rotor is pointing toward #1 plug at TDC combustion.

 

[nicholastheczar]

I'm going to pick up some starter fluid in the morning and try a little squirt of that and make sure my fuel delivery is good. If that doesn't work then I'm going to try and set it at TDC one more time, recheck everything, and give her a whirl. If no dice, then i'll call painless and see if they can't help me. As I was typing this I pulled up my painless TBI manual from summitracing and the one they have online for my TBI is newer than the one that was in the box from painless. The one I got in the box w/ my TBI kit is missing some paragraphs and is layed out differently.

You asked me about the brown/white wire...no you will not need to put engine back on tdc as long as you've already done this along with putting rotor on correct spot. Disconect that wire with power off once engine starts and warms up thats when I would try and put timing around 4-6degrees btdc which would be ccw rotation. You need to have timing marks..mine didn't I had to add them. once you have that stop engine and reconnect wire. disconnect battery to clear number 42 code....then test drive, if you can get your hands on a hand held scanner you will want to go for a drive and have someone watch the knock sensor...you will need to search for what will be a proper reading...I haven't done that step yet.

also howell performance was a great help for me...they use stock gm componets!!!

Note when I was trying to starts and I could tell It was trying I had to open the throttle...Now that the engine has started, I do not have to do that any more it fires right up!

Also look into the fact that you have parts from diffrent cars, I think i remember you have to becarfull when doing that...just google tbi troobleshooting

 

[miker]

Sorry if you have already gone over this but, when you turn the ignition to on, does the fuel pump run for a second or two? It should run and pressurize the feed line to the throttle body. I think you need about 15 to 20 PSI at the throttle body. If you don't have pressure, I don't think the injectors will fire enough fuel for the engine to run.

 

[nicholastheczar]

Yes, the system is pressurizing when then the key is turned to the run position. I have a fuel pressure gauge that is showing about 13-15 psi when it is pressurized.

Sorry if you have already gone over this but, when you turn the ignition to on, does the fuel pump run for a second or two? It should run and pressurize the feed line to the throttle body. I think you need about 15 to 20 PSI at the throttle body. If you don't have pressure, I don't think the injectors will fire enough fuel for the engine to run.

 

[Trollhole]

I've had one little bang that sounded like the engine was going to try to start, but it was quick and then it was gone.

ECU was out of a auto, 88 chevy suburban w/ 700R4 I believe. I have a 700R4 in my 40.

Which wire is the enrichment wire? I have a painless wiring harness. I'm at work and don't have my vehicle or booklet w/ me. If I remember correctly, I have my vehicle speed sensor wire and my park / neutral indicator switch wired together which is what my painless wiring harness calls for.

Maybe purple or purple white. Best is to connect it to the starter solenoid. ECU has to know your actually trying to start the vehicle.


Also you can take that oil pressure sensor out of the loop. Just connect the wires together. I'm not sure of the function during starting but the ECU that has this feature is looking for 4psi. Though I would think it would look for that only after a set time.

 

[nicholastheczar]

Well I figured it out!!! I was on the phone w/ Painless double checking my wires. I cranked my engine to check an ignition wire and the tech thought my starter sounded funny. My starter was the only thing that I haven't replaced. So off to autozone and come back w/ a new starter. Hook it up and ... nothing. I thought for sure somehow that would start it but it didn't. I decided to do a compression test on all of my cylinders. Mind you this 350 came w/ the cruiser when I bought it but had never been hooked up at all, just put on some old crappy motor mounts (which I replaced w/ Matt Beir mounts) and thats it. I check compression, #5, #2, #8 all had ZERO compression! I flipped, I thought my motor was bad! The PO had cranked the rocker arms down and I had loosened them up to where I could turn the pushrod w/ my fingers. Well apparently I hadn't loosened them enough. So I loosened the rocker arms quite a bit and did another compression test and voila - 165psi!!! So, I hooked all my junk back up (make a little wish), hold my tongue just right, and VROOOOOOOOOOMMMMMMMMM!!! It's Alive!

And freakin loud!!! I only have exhaust manifolds on so she sounds like a drag car ready to make a 7.823 second quarter mile run.

So compression, that was the key. All my wiring was right, fuel was good, spark perfect, timing spot on, just compression. Thanks to all of you that helped me out. I did the Toyota jump when it fired up!

Nick

 

[kblack77]

right on!!!!!