First off, I can't thank everyone enough already. I had no idea where to start looking for why my car wouldn't run, and I've learned an amazing amount already... but not enough to fix my car.

I have a 1990 Formula 350 (L98 with TPI). It sat up for a while because the brakes were shot. I fixed the brakes and was thrilled to be driving it again. We went on a trip ~300 miles or so, and I filled up when we got home. Way low on gas.

The next morning I went to move it and it ran like total garbage for the 30 seconds it took. Later in the day, I went to fiddle with it, and it cranked strong, but wouldn't start.

I chased down threads here about what to do... and here's what I got...

It starts with starting fluid into the intake and sounds good when it does. As soon as the fluid burns off, though... it dies out.
There is fuel at the rail.
The pump runs. (you can hear it)
There is strong spark.
The injectors are all 16.7-16.9 Ohms.
The pickup coil is at 850 Ohms.

At this point, I decided to give it to a mechanic.... I'm a real-live newbie, and I know it. I figured it might be a bad pump/fuel filter restriction or something, and I have no good place to spill 16 gallons of gas right now.

3 mechanics spent two days on it and they gave it back to me. They couldn't start it either, but they did measure fuel pressure (45-50) and scanned it while trying to start it, but didn't find anything. They also tried a new computer and a new module, but it acted the same. They told me, "There's nothing wrong with this car... except that it doesn't run." Nice.

Sooo... I bought a "noid" light and checked the injector pulse myself and it's regular... but it's dim. Really dim. I can't imagine that an impulse that weak (too weak to fully light a little bulb) could make the injector fire. And they're all that way.

I had the ECM checked at a parts store, and it was shot (from cranking in vain?), so I put in a new one. No luck. Same deal. I also have a new pickup coil, but the point is splined on and I'm guessing you have to take out the distributor to replace it?

Sorry for the really really long first post, but with as much as you know about the 350, I thought as much info about where I am now and what I've tried already might expedite things a bit. (plus it proves I know where that "search" button is) If anyone has ideas about a next step, please let me know. I'd really appreciate it.

E

 

This may help... I had a similar problem with my car, but I'm using an aftermarket fuel injection system and ECU. It was running like crap on night leaving work and it died on me about a quatermile out of the parking lot. I had to call my dad to tow me home with the van. I hooked up my laptop and everything was working perfectly, except that it didn't run. I called holley and they determined that the ECU must have went bad and they were about to replace it for free, but they told me to check the fuse anyway, even though the ECU had power. the fuse to the ECU was dirty and corroded causing not enough current to flow to fire the injectors. No fuel was my problem, but the reason was corrosion inside of a fuse weather pack.

 

I'm a newbie also but have a well rounded knowledge of cars. I have a 1989 IROC-Z and I'm having the exact same problem as you. My car sat for 3 years instead of months though, and I also had 3 mechanics look at the car and not be able to fix it. Off course they still charged for their time though. I have tested everything just like you, ECT..... I will be watching this post and will be working on my car all weekend if I have to to figure it out. I'll let you know if I get mine to run and what was causing it!!!

Best Regards: cabsales1

 

My 89 did this too. Turned out the grounds weren't attached securely on the back of the heads.
The injector harness gets power whenever the key is turned to the on position, but the injectors do not fire until they have a ground pulse. If your test light looks weak then maybe the voltage is low. If your light looks strong but just doesn't pulse, then maybe it's a bad ground like I had.

Try this. Hook another running car up to yours via jumper cables and wait until you get a good 14 volts on your gauge, and then try starting it.

 

The battery was almost new, and after a long trip had a good charge for a long time during the process. I already checked the grounds thanks to your post in another thread, TPIgirl. Great guess, but not it. I've also been charging the battery overnight as needed for working on it the next day. I'll check the fuse to the ECU today and let you know. Thanks for the suggestions.

 

Okay... rechecked the grounds and fuses. All good. Replaced fuses anyway. No difference. Hooked it up to my jeep just in case (TPIgirl's suggestion) and same. Other thoughts? Plugs are bone dry... no surprise, but I checked anyway. And I really think it's because the injector pulse is too weak. I also "wiggle tested" the computer and module... Now I'm just aimlessly fiddling. Other thoughts?

 

Did you say that you tried a different ECM already?

A friend of mine had a similar problem but it wasn't his grounds. He had a bad fusable link. The wires inside the insulation were broken. I don't know how possible that is to be your problem.
I think there are two different power wires that go to your ECM. I can't remember which one the injector driver uses. Someone in the DIY PROM section should know that.

A mechanic I know always says to check the harness plugs when there is an electrical problem. It's never worked for me though.

 

Mechanic tried a new ecm and no difference. I replaced it anyway when I got the car back. The old one tested out bad. Not that that helped. I now have a good ECM in my non-starting car. My next logical step is to sit and stare at it...

I'll recheck the wires. At this point, I'm not even sure if it IS electrical. I'm very seriously considering buying a new set of injectors and putting them in just to see. They test out okay resistance wise, but could they get mechanically stuck? I'll probably need to tear it down when this is all done just from cranking it dry.

At least I'm learning... lots... fast. And it doesn't look like the curve is going to get any shallower as I go.

 

If you don't have a digital multimeter, go get one. We'll wait....


:lala:


O.K.

Test the voltage at the injector connectors. Just pick one that is easy to access. You've obviously found at least one since you were able to plug in the 'noid test light. With the ignition turned ON, you should be able to read full battery voltage from the injector power to a good (battery) ground. If so, the INJ1 and INJ2 circuits, fuses, ignition switch, fusible links, and everything else are probably all intact. That eliminates about half of the system straight away.

If not, check all the above mentioned items.

Presuming the voltage is at or around 12.6VDC or higher, test it again, but this time reference the engine as a ground instead of the battery. Since the starter evidently cranks well, there is likely going to be no difference in your readings. If there is, start looking at teh negative battery cable, engine/chassis ground strap, and ground connections from the battery cable to the body (if equipped).

If you've gone this far and still have battery voltage, the problem is likely in the ECM side of the injector harness. Go back to the passenger side footwell, remove the lower bolster trim panel, and expose the ECM. Remove the two retaining screws and drop the ECM and its bracket down so it is accessible. You've apparently already been there.

Check the resistance between the ECM case and a good chassis or engine ground. It should be dead-on zero ohms. If not, inspect the ground connections at the ECM and in the passenger compartment. Temporarily connect a ground wire to the ECM case stud and a good ground, and try starting again. If that solves the problem, you need to trace the poor ground.

If grounding the ECM does nothing to help, disconnect the ECM connectors and meter the resistance from the C-16 and/or D-14, D-15, or D-16 connections to the ground pin of one of the injectors plugs. (Those are the ECM connections for the grounded side of the injectors.)
You'll likely need an extension wire to allow your meter probes to reach. There should be dead-on zero ohms. Any resistance here is a problem. Start looking at the wire harness soldered splices if there is any resistance.

We'll wait...

 

Thanks so much for taking the time to spell it out. I do, in fact, have a multimeter... and a printer ... so as soon as I get a couple of hours to do it, I'll plow through that list piece by piece and let you know what I find. The good news is that by now I've been staring at it long enough to know where almost all of those things are. I really appreciate the direction.

 

I went through the list and learned a LOT. Nothing that started the car, though. My last guess was that I was reading too much into things I least understood (electrical) and not giving any credence to the improbabilty that fuel stopped at the all of the injectors... even if the injectors weren't "bad" per se. Over the last couple of months I took it all apart (followed the injector swap tech article using SVO injectors) and put it back together and it runs like it never missed a beat. Yeah!

The car's been up for over a year now, and the dash lights didn't work... but a completely different thread saved me many, many hours of guessing on that one, too. I plan to have it legal this week and put the Jeep away for the summer. Thanks for the advice on all counts. There is no way I could own this car without this site.