SBC TBI troubleshooting (2 Viewers)

[nicholastheczar]

I'm trying to fire up my sbc tbi setup right now and having a problem. I checked and I am getting fuel delivery and am getting spark so my guess would be timing. I installed a new dizzy and set the #1 cylinder at TDC and reinstalled my dizzy. My question is I've read that some during this step have there's 180* off. I'm guessing that is maybe what I've done here. How do I check to see if this is what I've done and correct it? It is just pulling the dizzy and turning the crank pulley? When I check for #1 cylinder at TDC I pulled the fender, exhaust manifold, and spark plug so I could see the top of the cylinder. With my #1 at TDC I rotated my dizzy to point close to the #1 cylinder and my dizzy cap, once installed, was pointing at my #4 cylinder. Thoughts?

Nick

 

[cmiller114]

#1 piston at top doesn't mean TDC...it could be the exhaust stroke. You need #1 piston at the top just after the #1 intake valve closes, then you at at TDC.
The gear on the dizzy will turn the shaft 20 degrees or so. Just get it close and then after you install the dizzy turn the housing so you're pointing at #1 or just after.....this will get you close.

 

[nicholastheczar]

I used a multimeter and checked my coil w/ the key in the run position and had power at the coil and in the injectors. I did not check it while cranking it, but I assume that if I am getting spark (which I did check while cranking it) that I would have power to the coil during cranking.

Are you getting power to the coil while you are trying to fire up?

If you hook to the wrong wire on the column, you will get no power to the coil while starting.

W/ the intake manifold on, how can I check to see whether or not it is in the exhaust stroke or not? I have no marks on my timing cover for TDC.

#1 piston at top doesn't mean TDC...it could be the exhaust stroke. You need #1 piston at the top just after the #1 intake valve closes, then you at at TDC.
The gear on the dizzy will turn the shaft 20 degrees or so. Just get it close and then after you install the dizzy turn the housing so you're pointing at #1 or just after.....this will get you close.

 

[lone gunman]

check these out YouTube - Install chevy small block distributor YouTube - How to Install Distributor Video-Engine Building Repair DVD YouTube - Replace classic chevy distributor with HEI YouTube - Engine Ignition: Wiring Distributor & Spark Plugs Video- DVD hope one of these will help if not go to you tube and search or google.

 

[nicholastheczar]

Thanks for the links. I've been all over youtube looking at TDC etc, saw a few of these but not all. I'm beating my head against the wall now. I don't know what I'm doing wrong.

check these out YouTube - Install chevy small block distributor YouTube - How to Install Distributor Video-Engine Building Repair DVD YouTube - Replace classic chevy distributor with HEI YouTube - Engine Ignition: Wiring Distributor & Spark Plugs Video- DVD hope one of these will help if not go to you tube and search or google.

 

[dlbrunner]

pull the number one spark plug. wad up some toilet paper and put it in the hole.

Crank starter a milisecond at a time (just make it barely turn) when the toilet paper "Pops" out you are on the compression stroke.

Redneck, but it works

To find TDC that is

 

[nicholastheczar]

I've been putting my finger over the hole to feel for air "rushing" out of the spark plug hole. When I feel the air coming out, I use a flash light to look inside the cylinder and use a socket wrench to crank the crank pulley until the piston is no longer traveling upwards. That should be top dead center, right?

pull the number one spark plug. wad up some toilet paper and put it in the hole.

Crank starter a milisecond at a time (just make it barely turn) when the toilet paper "Pops" out you are on the compression stroke.

Redneck, but it works

To find TDC that is

 

[psreno]

Exactly what did you mean by "installed new dizzy"?

Cap on backward? (stupid, but trying to eliminate as much as possible)

Plugs fouled?

 

[Radd Cruisers]

Some systems work on constant power with the ground being interrupted to generate the spark and injector pulse. Power at the coil and injectors does not mean that things are going to work as a result...

Also, you need to take into account the helical cut of the gears when installing the distributor and allow for the extra rotation that occurs. Once the dist. is in place the rotor needs to be pointing at the correct pole in the dist.

As your system is probably OBDII, it might be worth checking for any codes that have been generated. You didn't, however, tell us exact year of your TBI system...

~John

 

[kblack77]

I just went through this same problem when i had to reseal the intake...and a buddy gave me a high performance one for free.

Make sure after verifing the wires are in correct position

Info on V8 Engine Firing Order

rotor is pointed to number 1 while number one is at tdc

disconnect the brown/white wire with power off...I forget name of this

try and start fj...you may need to not only try moving dizzy but also on mine this one and only time I had to open the throttle to get some air into engine.

set timing..mine worked best at 6deg btdc then shut off fj. Hook brown/white wire back up and disconnect battery for 30seconds to clear the #42code

good luck

 

[nicholastheczar]

I installed a new distributor for a 89 Chevy 1500 TBI pickup. This cap can only go on one way. Brand new plugs, none of which are fouled, still look brand new.

Exactly what did you mean by "installed new dizzy"?

Cap on backward? (stupid, but trying to eliminate as much as possible)

Plugs fouled?

When I seated my new dizzy, I adjusted it so that when it slides in the oil pump gears it was pointing as close as I could get to #1 cylinder. I then turn the entire dizzy so that the body rotates to match the points on the rotor. Is that right? This picture is from after trying to start it. I pulled the dizzy cap and snapped this w/ my phone.

I then put the cap on and put the plug wires to the (in the firing order of the dizzy) to the correct cylinder (1,8,4,3,6,5,7,2 clockwise). The ECM is a 7747 out of a 88 or 89 Chevy suburban the the throttle body is out of a 90 Camero 5.7L.

Some systems work on constant power with the ground being interrupted to generate the spark and injector pulse. Power at the coil and injectors does not mean that things are going to work as a result...

Also, you need to take into account the helical cut of the gears when installing the distributor and allow for the extra rotation that occurs. Once the dist. is in place the rotor needs to be pointing at the correct pole in the dist.

As your system is probably OBDII, it might be worth checking for any codes that have been generated. You didn't, however, tell us exact year of your TBI system...

~John

I just disconnected my brown /wht wire after trying to start it. Do I need to go back now and set it back to TDC after disconnecting the brown / wht wire? When you say your worked at 6* BTDC did you rotate the housing of the distributor counter clockwise approx 6* from 0*?

I just went through this same problem when i had to reseal the intake...and a buddy gave me a high performance one for free.

Make sure after verifing the wires are in correct position

Info on V8 Engine Firing Order

rotor is pointed to number 1 while number one is at tdc

disconnect the brown/white wire with power off...I forget name of this

try and start fj...you may need to not only try moving dizzy but also on mine this one and only time I had to open the throttle to get some air into engine.

set timing..mine worked best at 6deg btdc then shut off fj. Hook brown/white wire back up and disconnect battery for 30seconds to clear the #42code

good luck

 

[nicholastheczar]

Front Drivers side - #1 cylinder at top dead center. Used a wrench on the crank pulley and held my finger over the spark plug hole and turned the wrench until I felt air coming out. Then I watched and slowly wrenched the crank (clockwise) and watched the piston raise until it stopped (TDC) right? Now I will drop my dizzy in.

Dizzy installed, I don't know the proper terminology here but the rotor is pointing at #1 cylinder and the distributors points line up w/ the rotors points while at TDC. The dizzy body is facing the front of the engine w/ maybe 2* or 3* towards the #1 cylinder (all points inside dizzy line up.)

Snug down dizzy cap. The tower that the rotor is pointing at is labeled #1 and the #1 spark plug wire goes to my #1 cylinder.

All plug wires are on and going to respective cylinders.

Dizzy is plugged into distributor connection from ECM and Coil is plugged into dizzy.

Belt is put back on

Brown / blk wire on painless harness is disconnected to set base timing to 0.

Ready to fire. Lets cross our fingers!

Nick

 

[Mad Chemist]

Hi there, I just finished my TBI swap this week. As another mentioned- make sure your ECM is hooked up to a wire that's getting 12V during cranking. If not, you'll get spark, and it'll crank over, but the injectors won't be squirting fuel into the throttle body. Hooking the ECM to the ignition wire that used to go to your old distributor is one idea.

One way to trouble shoot this is to put a squirt a bit of starter fluid into the throttle body while cranking, and see if it fires up. Once the engine starts, and you stop cranking on the starter, the injectors will get 12v again and continue to run. If you're getting compression and spark, and the timing is reasonably close, it should at least run (if not really well).




As far as I know, all TBI systems are OBDI, could be wrong on that.

 

[nicholastheczar]

It looks like I am getting fuel to the system because when I'm done cranking, there is fuel on the butterfly valves in the throttle body. I will try this though because I'm really stuck. Right now I have the ECM power wire hooked up to my ignition wire (Painless #920 - Pink).

Hi there, I just finished my TBI swap this week. As another mentioned- make sure your ECM is hooked up to a wire that's getting 12V during cranking. If not, you'll get spark, and it'll crank over, but the injectors won't be squirting fuel into the throttle body. Hooking the ECM to the ignition wire that used to go to your old distributor is one idea.

One way to trouble shoot this is to put a squirt a bit of starter fluid into the throttle body while cranking, and see if it fires up. Once the engine starts, and you stop cranking on the starter, the injectors will get 12v again and continue to run. If you're getting compression and spark, and the timing is reasonably close, it should at least run (if not really well).




As far as I know, all TBI systems are OBDI, could be wrong on that.

 

[Mad Chemist]

You'll sometimes get a very short squirt right at the end of cranking, so I'd try the starter fluid trick. That, or have someone watch the injectors while you're cranking and see if the injectors are firing.

 

[nicholastheczar]

I'll try it.

You'll sometimes get a very short squirt right at the end of cranking, so I'd try the starter fluid trick. That, or have someone watch the injectors while you're cranking and see if the injectors are firing.

 

[cruiser enthuiser]

Just sent ya a PM, but it looks like you got the dizzy/TDC worked out. I hope you get it started.

Did you say you for sure are getting spark? To test mine I just pulled a plug and cranked it with the plug close enough to the body to arc across. Careful, dont shock yourself.

My factory harness has a wire coming off the fuel pump relay where I could connect 12v power and prime the fuel pump. I did this before starting for several seconds...if you're already getting fuel maybe not needed.

Thats all I can think of for now. May want to review your wiring diagrams. As mentioned previously, some circuits cut out when you're cranking the ignition. I went thru this when I recently re-wired mine. Everything tested fine with the key on but the injectors would cut out when I cranked it....

Good Luck!

-Ed

 

[nicholastheczar]

I got your PM. I ended up buying a painless TBI harness and have my old chevy tbi harness sitting in the corner. I checked my spark on cylinder #1 and it is good, I haven't check any other cylinders but I will tomorrow when I get home. I'll check the injectors too when I get home to make sure they are getting spark when i crank it.

Thanks for the reply.

Nick

Just sent ya a PM, but it looks like you got the dizzy/TDC worked out. I hope you get it started.

Did you say you for sure are getting spark? To test mine I just pulled a plug and cranked it with the plug close enough to the body to arc across. Careful, dont shock yourself.

My factory harness has a wire coming off the fuel pump relay where I could connect 12v power and prime the fuel pump. I did this before starting for several seconds...if you're already getting fuel maybe not needed.

Thats all I can think of for now. May want to review your wiring diagrams. As mentioned previously, some circuits cut out when you're cranking the ignition. I went thru this when I recently re-wired mine. Everything tested fine with the key on but the injectors would cut out when I cranked it....

Good Luck!

-Ed

 

[76 PTO]

I have a 92 setup and your distributor looks 180 out on the body not the rotor. Mine has the plugs for the dizzy facing towards the fire wall. Just a thought.

 

[nicholastheczar]

Correct me if I'm wrong, but wouldn't the body direction be directly related to the orientation of the rotor? So if your rotor is facing #1 cylinder while #1 is at TDC then your distributor body will be facing that direction also. If you setup your distributor w/ your #1 plug wire facing the firewall then the distributor body would also be facing the firewall.

Nick

I have a 92 setup and your distributor looks 180 out on the body not the rotor. Mine has the plugs for the dizzy facing towards the fire wall. Just a thought.