u r sofa king we tah did

my car is cranking but not firing. timing is correct 6 BTDC and balancer is new so ring is not slipped. i switched to stealth ram and it ran fine but developed a problem. it cranks but never fires. i pulled a plug and it got spark. i had my finger on the injectors while cranking and i didnt feel them click. ignition module and coil are both tested good and tried on other tpi car. two computers were tester, one known definate working one. still no clicking from injector. how is the pulse controlled? is ground or 12V switched from the ecm and which one is constantly supplied? and if you know the colors that would be even better. i did check the fuses and they were good, so was fuel pressure.

Scott C

Make sure the short coil wire is connected. I left mine off and it did the same thing...did you say you had spark, though? Are you positive?

u r sofa king we tah did

whitish blue spark at the plug. is there any way VATS will allow cranking but wont pulse the injectors?

Morley

Take a connector off of one injector and turn the key on, put a test light between each terminal on the harness and ground, the light should be on. If that is good, put the light across the terminals and have someone crank the engine, the light should flash, if not, there is an open in the distributor ref pulse wire somewhere.

kevinc

I'd start by verifying the ECM is powered...jumper the ALDL diag pins and verify you get code 12 repeatedly.

Both starter and ignition operate independently of the ECM (in all 3rd gens I've seen thus far), but the injectors are ECM-driven. Given yours spins and sparks, the ECM is a good starting place.

After you know the ECM works, check what Morley mentioned with a scantool. Watch it while cranking, you should see ref pulse activity (time since last ref pulse field).

u r sofa king we tah did

there is no light when cranking, so no pulse. is it a vats module problem?

the engine fired once and ran out of the blue until i let off throttle and it died. then i killed the key and started removing tools from under the hood. went back to start it and it just cranked again. the ecm isnt the problem, 2 of them have been tried out in another car.

kevinc

My next step would be to check for a loose connection at distributor, or loose connection on the grounds at rear of the cyl heads.

Morley

Not Vats related, Vats won't let the car crank at all (or not supposed to)

u r sofa king we tah did

cyl head grounds looked and felt ok, will check in daylight and clean connections. this has me

Bort62

The ground for the ECM is in the mess of wring harness At the rear of the intake.

Easy one to Miss.

u r sofa king we tah did

you are talking about the grounds on the back of the heads right? what if i spliced a good ground directly into the ecm with a thick wire from a good known ground?

u r sofa king we tah did

all grounds were in harness connector were checked with a voltmeter and when connected with a power source they all showed 12V+ AHHHHHHHHHHHHH! sorry. does anyone have a 87 350 TPI chip without vats that they dont want or replaced? or does someone know how to build a square wave generator? this is getting so frustrating im about to buy a painless speed density harness and convert to SD.

espirocz

iTrader: (2)

Did you install diffrent injectors when you installed the intake base? The injectors I installed created to much resistance when warmed, and the voltage drop through the ignition system was to severe to fire warm injectors. I had to run 12volts from battery thru relay to solve that.

The injectors are fired by the ecm grounding the circuit. each bank has its own circuit. with the key in the run position you should get 12volts to one side of the inj. wire harness. And the other will ground to close circuit

With my problem I could pull the brake booster hose off of the intake and squirt a 1 second blast of carb cleaner in the intake and it would fire off of that and start running.

Good Luck.

ir0cflamez

Morley is right. Definitely not VATs related. Vats wont let your engine turn over at all. I would disable VATs though. It sucks when you are stuck at the store when you have to be somewhere! It's going to go soon anyway!

As far as the inj problem, I have no idea. I'm on painkillers right now and cant even begin to think about inj puse width

u r sofa king we tah did

its vats related. the car previously had an alarm, and the starter relay was wired into that, then the alarm was removed before i bought the car and the relay was wired directly to the key. thats what had me stumped then i remembered and looked at the wiring and saw it. im getting a non vats chip, should solve the problem.

Morley

Heh, you never mentioned the hack job done to Vats.. that in and of itself will cause no end to headaches. I wouldn't count on a "nonvats" chip fixing the problem if the wiring is as butchered as you indicate.

u r sofa king we tah did

well without the chip i have the injectors firing, i wired vats back up right because the module was still in the car. low and behold it still works. the injectors started firing. now the car is sputtering but wont catch and run. any ideas on that one? i also changed the ignition rotor because my old one looked like hell. i think im going to do plugs tommorow just for grins because they are about a year old.

Morley

Make sure you have good spark to start. Change the cap, rotor (you just did), wires and plugs, possibly coil. Once you are sure you have good spark, if it still sputters like it is "trying" to fire off, it will be time to look at fuel delivery, replace the filter to start. There is a check you can do with removing the fuel pressure line at the manifold and crank the engine, there is a specified amount of fuel you should get in so many seconds of cranking. Someone here should be able to point you to the exact info, if not I'll go digging through my books, it is in one of them.
Once you know you are getting proper flow make sure the injetors are firing (all 8 of them), a mechanics stethoscope placed on each injector while cranking should tell if they are opening and closing (ticking noise).
If all that checks out and you have done some serious mods to your engine, you may need to burn a chip with extra fuel for starting, just so you can see what it needs for fuel to run.