tbi v8 swap no injector pulse (1 Viewer)

[blackandbluefj]

well here is the problem all i finally am done the v8 swap into my 60 except for exhaust. well the truck turns over with no problems, timing is on close enough to run on starting fluid. fuel pump on runs and puts out pressure up to the throttle body the only problem is there is no injector pulse. there is spark and everything looks good, and im pretty sure all connections are made. the question is now what do i look for i checked the wires to the injectors and i have 12v to the drivers side of each both with ignition on and off. what do i look for next. does the oil pressure switch have anything to do with this circuit. help me out please i am almost there after almost a year, next up soa


thanks all


Bryon

 

[Gumby]

Could be two causes - no fuel, or no pulse signal


Pulse signal can have a number of causes.

You need 12V to the injector on 'run' and on 'start'. you should not have it when the key is off. It seems you have this.

The ECM needs to ground the other wire to the injector. It could be the quad drivers in the ECM are shot, but there are a lot of other things to check first. Usually you get no ECM pulse because the ECM doesn't know it should be pulsing.

The most common cause for this is the purple wire isn't getting a crank signal. The purple wire should be connected to the starter solenoid so when you hit the key to start it gets 12V.

If that's hooked up right you should get a measured pulse that will get the engine to start. if it dies right after the problem is in the distributer signal.

If you have no fuel to the injectors, the problem is either the pump, pump signal or lack of fuel. (it does have fuel, right? )

This is really easy to check. Crack the line on the back of the TBI unit and cycle the key to on. It should spray fuel for a few seconds, then shut off. If it does not, check for power at the pump. If you have power at the pump for those few seconds, then you need a pump. If you don't, then you have a relay or relay signal problem.

The relay should get power from the ECM when the key is turned to on. It will run for a few seconds before it sees a crank signal. If it sees a crank signal it will run while cranking and a few seconds more. Once the car is getting oil pressure, it will run continuously until it looses oil pressure or the key is turned off. So-check the power out of the relay. If none is present, check the power going in. If that's good, check the trigger power. It should come on when the key is on or when cranking. ALso check the ground for the relay, just because.

The oil pressure sending unit bypasses the relay when the engine has oil pressure. It doesn't do anything on cranking or for a few seconds after.

If that doesn't get it, post up and we'll go from there.

 

[brokenparts]

Could be two causes - no fuel, or no pulse signal


Pulse signal can have a number of causes.

You need 12V to the injector on 'run' and on 'start'. you should not have it when the key is off. It seems you have this.

The ECM needs to ground the other wire to the injector. It could be the quad drivers in the ECM are shot, but there are a lot of other things to check first. Usually you get no ECM pulse because the ECM doesn't know it should be pulsing.

The most common cause for this is the purple wire isn't getting a crank signal. The purple wire should be connected to the starter solenoid so when you hit the key to start it gets 12V.

If that's hooked up right you should get a measured pulse that will get the engine to start. if it dies right after the problem is in the distributer signal.

If you have no fuel to the injectors, the problem is either the pump, pump signal or lack of fuel. (it does have fuel, right? )

This is really easy to check. Crack the line on the back of the TBI unit and cycle the key to on. It should spray fuel for a few seconds, then shut off. If it does not, check for power at the pump. If you have power at the pump for those few seconds, then you need a pump. If you don't, then you have a relay or relay signal problem.

The relay should get power from the ECM when the key is turned to on. It will run for a few seconds before it sees a crank signal. If it sees a crank signal it will run while cranking and a few seconds more. Once the car is getting oil pressure, it will run continuously until it looses oil pressure or the key is turned off. So-check the power out of the relay. If none is present, check the power going in. If that's good, check the trigger power. It should come on when the key is on or when cranking. ALso check the ground for the relay, just because.

The oil pressure sending unit bypasses the relay when the engine has oil pressure. It doesn't do anything on cranking or for a few seconds after.

If that doesn't get it, post up and we'll go from there.

wow, I know who to ask if I end up with TBI issues.

 

[blackandbluefj]

well thats what that crank signal wire is supposed to be connected to. I guess i'll try and hook that up tommorrow, and hopefully that solves the problem. but yeah everything else is good spark and fuel just no pulse. well we will see tomorrow.



thanks

Bryon

 

[Markh]

Do you have the engine service light hooked up? I had this same problem with my EFI conversion.
I wasn't getting any spray out of my injectors but everything else looked good.
If the engine service light goes out while your cranking you aren't getting enough power to the computer. As soon as the computer loses power the engine won't start.
I installed an electric fuel pump relay in mine so as soon as I turn on the ignition it gets power directly from the battery.
Check your grounds!

Good luck

Mark

 

[blackandbluefj]

crank signal hooked up and still no injector pulse. 12v to the red and white wires and 12v to the wires at the ecm with the key on and the injectors checked in spec for resistance. i checked all other wires at the ecm for voltage and the eac wire has no voltage. no i may be brain dead today so what is the eac i cant find it in any book and i have no idea where to look to see if i wired it up. help me all so i can get this to the muffler shop and then to the trails i have been without the cruiser for about a year now


thanks all
Bryon

 

[Gumby]

12V constant power to the orange wires and 12V ignition switched power to the pink black wires?

Good grounds on all the white/black wires?

 

[FJBen]

x2 on the grounds...they are the plague of electrical issues. After I swapped from I thought a good ground to right off the battery, things worked MUCH better.

Did you crack your fuel line to check if you are getting fuel? We took mine off and ran a straight hot wire to the pump to get it going. It took probably about 45seconds, then we heard the tone change on the pump and we got fuel.

Just a thought...

 

[lc tpi]

i had the same problem when i swaped a tpi in my 40 , injectors would not pulse. i rewired my cruiser and put a chevy tilt coulumn in it and when i hooked up the power 12v for the ecm the circuit i hooked it to would drop off when you crank it over . check to see if the circuit you are tied to does not drop the 12v when cranking. just a thought.

 

[blackandbluefj]

congrats lc tpi you win. i hooked the pink black wire to a switched on 12 v but failed to also check to see if it was 12 v on while cranking. fixed that and she fired right up. sound klind of nasty with them 3" long tube headers. guess i need to get to the muffler shop now. thanks all



Bryon