GM TBI kicking my butt

binderbound · May 25, 2006

Basically I took a TBI set up from a chevy pickup and put it on my IH. I did remove some wires from the harness but I'm still running 98% of the sensors.

Problems are... Fuel pump wont shut off. It runs for a second when you turn the key on. Then when you try and start it, and return the key to 'run' the fuel pump runs and runs. So much that it fills the throttle bores full to the top:wtf: I know the relay is energized by the ECM, so my guess is the ECM thinks the truck is running when its not.

Also, I got no spark at the plugs. I have 12V at the coil. I have 12V coming out of the coil going to the ESC, but nothing at the dist. It is a hybrid dist but it ran 3 days ago with duraspark and a carb.

I did all my voltage checks at the ECM and they are perfect in the key on position. My grounds are perfect. My ESC is grounded with heat sink goop on it. My realys are wired correctly. I'm running out of options in a hurry.

Any help???

Major Screwup · May 26, 2006

Dizzy Pickup

Make sure you don't have the wires from the dizzy reversed where they connect to the esc! :haha:

Toyoda1 · May 26, 2006

Look up a harness manual online, I bet you have some wires crossed or put to wrong pins. When I did a S/B swap in a fiero with a stand alone managment F/I system we had the same problem. Turned out that we had 2 wires in wrong locations on the ecu to harness pin. Just something to look into.

CrustyJeep · May 26, 2006

binderbound said:
Problems are... Fuel pump wont shut off. It runs for a second when you turn the key on. Then when you try and start it, and return the key to 'run' the fuel pump runs and runs. So much that it fills the throttle bores full to the top :wtf: I know the relay is energized by the ECM, so my guess is the ECM thinks the truck is running when its not.

Your pump should be able to run all day without filling up your throttle bores... You got a leaky ass injector or something. That's what I would attack first, just because you know it's broke and you can't run it like that.

binderbound · May 27, 2006

my buddy :flipoff: 'major screwup' has it right. the ECM only opens the injectors when it gets the signals that power is going through the dist. I had 2 wires crossed up, so when we tried to start, the 12V was going to the ECM instead of the dist. The injectors have 12V all the time. The ECM just grounds them, causing them to open every time it gets the word from the dist.

wheelinjp · May 27, 2006

so you fixed it then? to my understanding you have to run a gm distributor, or electronic equivelant, so is your dist the right one? The other thing is the fuel system return line. Did you run another line back to your tank? It has to be functional for it to work. Also did you buy a f/i rated fuel pump? the tbi system only needs 15.8psi to function, but the throttle body regulator should be able to handle up to 60psi and regulate it down. So if you blocked off your return line it will flood, or if your regulator is bad, too. Good luck, and when its done these motors are very reliable and run for a long time. I have been wheelin mine for 3 years.

binderbound · May 28, 2006

wheelinjp said:
so you fixed it then? to my understanding you have to run a gm distributor, or electronic equivelant, so is your dist the right one? The other thing is the fuel system return line. Did you run another line back to your tank? It has to be functional for it to work. Also did you buy a f/i rated fuel pump? the tbi system only needs 15.8psi to function, but the throttle body regulator should be able to handle up to 60psi and regulate it down. So if you blocked off your return line it will flood, or if your regulator is bad, too. Good luck, and when its done these motors are very reliable and run for a long time. I have been wheelin mine for 3 years.

yeah, we fixed it. We run ford duraspark guts inside of an IH holley dist. That gives the EST the signal it needs. We have the fuel running 3/8's inlet and 5/16 outlet(just like factory) running right to the cell. External HP pump.

You wheelin an IH motor in a jeep?

junkyard jim · May 28, 2006

Anyone know what would cause this system to slowly stall out when idling as it warms up (like someone shut the key off) It has new IAS, stepper motor, MAP sensor and O2 sensor. (starts right back up) It's been getting worse lately. /hijack

binderbound · May 28, 2006

Your dist tells the ECM what's going on.if the EST isn't getting the signal from the dist to fire,it will die suddenly.I would suspect the EST.make sure it has a good ground and good connection to its heat sink.