Hoss50

I am trying to wrap up my TPI swap (88 MAF system) and I am running into a wall. I am getting spark to the cylinders, but I am not getting fuel. I used a NOID light to see if the injectors are pulsing and they are not.

What can cause the injectors not to pulse? I checked the 2 fuses that are built into the wiring harness and both are ok.

The computer spits out code 12. Any suggestions? What should I look at and what could be the problem. Thanks

Harley

Morley

Make sure you have power to the injector fuses. Next check the injector connectors themselves, check each one to ground, it should have 12 volts on BOTH pins. If this is all good and you still get no firing voltage to the injectors then you may have a problem with the tach signal wire going to the ECM or possibly the ECM itself.

87_TA

I had that problem with mine once and it was the ECM ground.
Just a thought,might be something to look at.
When I was reading voltage across the pins Everything had 12 volts! Even things that were not supposed to including the ground pin.

John Millican

iTrader: (1)

troubleshooting steps:

1) connect test light ACROSS an injector connectors two wires. The test
light should flash while cranking, if it doesn't flash continue......

2) probe each wire at the injector connector separately, each wire should
light the test light, if each wire lights the test light continue.........

3) touch one test light to the purple wire at the distributor with the other
end of the test light to 12 volts (effectively applying 12 volts to the
purple wire) and note other test light at one of the injectors, the injector
test light shall blink each time the 12 volts is removed from the purple
wire. If the injector test light blinks each time you remove 12 volts from
the purple wire at the distributor the ignition module is BAD.

Hoss50

Would spark reach the cylinders if the module was bad? I have spark but I am not getting injector pulses.

I am going to go try the above procedure now. Thanks

Harley

eric305TPI

My module did that to me. Would fire the coil but would not send the ECM a reference pulse. Also verify that your PROM does not have VATS on it or it will not fire the injectors.

Trickster

Have you checked the two fuses in the fuse block labeled inj 1 & fp/inj 2. BTW, you neglected to say what you had originally before you did the tpi swap. Did you change the wiring harness, ecm, & memcal as well?

The Trickster!!!!!!!!!!!!

Hoss50

I checked the 2 fuses in my painless harness and both were good.

My setup is: 85 K5 Blazer that I swapped from carb to TPI and I am still in the process of getting it running. I am using a stock TPI system with a Painless wiring harness. I am running an 88 Firebird MAF system. No VATS. Like stated above the 2 fuses in the harness looked to be ok upon inspection. Thanks

Harley

Hoss50

The module test bad threw the procedure above so:

I replaced the module Thursday night and tried to fire it up again and still no pulses to the injectors. WTF am I missing? I called Painless Wiring and they told me I should try and borrow and ECM and see if something in there is messed up. Is there anything else that would keep the injectors from pulsing?

The purple wire goes to the start correct? It is setup to mount on the smaller of the 2 posts on the starter solinoid. Is this correct. It has the small loop on it so it won't go on the large post that the positive battery cable connects to. What else do I need to check?

I rechecked the 2 fuses in the painless harness and they are both fine. Please help. I need to get this thing running sometime very soon. Thanks

Harley

John Millican

iTrader: (1)

If you did exactly what i suggested and the noid light pulsed each time you removed 12 volts from the purple distributor wire then you have already checked the ECM.

The purple wire is the referance wire, it talkes to the ECM and tells it when to fire the injectors during cranking.

You said the ECM and injector fuses are good. I am assuming you have checked your grounds too right? They're just as important as the power......

It's interesting you say stock TPI in a Blazer with a Painless wiring harness. You say no VATS too. VATS will cause no injector pulse. Just because you have MAF doesn't mean you don't have VATS. The ECM (and chip) my be from a '89 TPI and have VATS enabled or the chip may have been re-programmed.

Have you checked your noid light to make sure it's good?

You may e-mail me direct for more help if you want, I know how frustrating it is because i have done many checks.

john@lt1intake.com

eric305TPI

Verify that the resistance of the injectors are 12 to 16 ohms or close to that at 70 degrees F. A shorted one will prevent the computer from firing them. I chased that one for a few days.

Hoss50

In reference to the tach signal wire to the ECM mentioned above, which wire is that? I am not sure I hooked up my coil 100% correctly but I get spark. I have one wire on the grey connector connected to 12V power for the coil, and the white wire on the grey connector connected to my Autometer tach. Is that the right setup or is that the tach wire for the ECM. If so where should it hook too? Thanks

Harley

Morley

The harness should have tapped into the distributor wiring some where, the signal is picked up off of the ignition module.

Hoss50

Ok, then I should be good then. The harness plugs into the 4 pin side of the module and the 2 pin side hooks to the coil. Thanks

Harley