TranSurgeon, Per your comment: "the pump is switched on by the ECM during the prime mode, and then again when the ECM 'sees' ignition pulses"; How does the ECM 'see' the ignition pulses? Seems my system is shutting down within about 2 seconds of startup - could be related - ideas? Thanks, Elliott
Now it's more fustrating... Maybe I broke something... Hotting the ornge wire brings the fuel pump to life. And earlier today it would start for about 2 seconds and then shut itself off. Now nothing. The pump is on (can hear it), but no gas at the injectors like there was earlier - and it is getting a spark but it doesn't even seem to be trying to start now. Maybe just that I'm out of starter fluid. :( And the fuel like I didn't replace (the return line) has now sprung a leak. One of the tranny lines is still leaking, the ignition switch seems blown (hotting the ornge), and now something else (it seems). This project has turned really sour. I hate to take it somewhere arround here - that would be hundreds. And I don't see a use to having it in LI. Maybe it's time to sell it for a dollar. Elliott
FFFFFFFFFIIIIIIIIINNNNNNNNNNNAAAAAAAAAALLLLLLLLLLLLLLLLLLYYYYYYYYYYY It's Running!!!!!!!!!!!!!!!!!!!!!!!!!!!! Sounding Great!!! So to get it going I have:
It's getting frustrating because you are throwing jumpers in and doing other half-ass things to solve the problem, rather than looking for the root.
You have no power at the ECM B fuse. Find out why. Note the names of those 2 fuses: ECM B and ECM I. Those stand for Battery and Ignition. The ECM B fuse is ALWAYS hot. The Orange wire, therefore, is always hot. The orange wire has nothing, repeat nothing in common with the ignition switch. Well, about as much as the dome light, but still....
That same orange wire powers the computer. The computer isn't firing the injectors. There is a clue located somewhere in those last 2 sentences. Stop jumpering and use the old thinking cap. If you have a tone generator, break it out and chase down that wire break. If not, hook up the VOM at the fuse holder and work out from there until you lose continuity.
As a footnote, the injectors are powered from (In order) ECM I fuse (pink/black) to white wire injector 2, red wire injector 1, and then out green and blue to the computer, where the computer grounds them in pulses to fire the injectors. If your pink/black didn't have power, there would be no spark, since the computer would be off. So fix the orange wire. Oh, you might want to trace out the orange wire too, and fix it.
When you have 12 volts on all the orange wire, try and start it. Don't bother until you do. If it still wont start after that, then post back.
It's been running for a couple of hours now --- Thank GOD! And thanks NG! Is the computer fried??? If I pull the AB jumper it dies instantly. I have the oil pressure switch bypassed (and it doesn't make a difference - the connection isn't so good, but no diff (though that may be a test-mode thing)). The idle is too low- rigged a hose clamp to increase it (there's no idle screw on this one). So to pass inspection and drive it...
And YES I'M HAVING A BEER NOW!!!!!
My Stepfather's speculation on the computer... (Stepfather = race-car driver/mechanic does all his own work - keeps many vehicles going). Anyway, he suggested looking for more grounds - and speculated that maybe the computer isn't getting adequate ground - except via the test-jumper through the test-pin. Well it makes a little sense. Will look for such while fixing the gas and tranny lines tomarrow. Meanwhile, it's been running about
6 hours now - smooth, quiet, clean. Oil is clean, no oil or water leaks. So it's comming along OK. Thanks again NG - for listening, speculating, etc. Elliott
Smart man, your stepfather. Any chance that some of it might rub off?
It makes a lot of sense.
The ECM "sees" ignition pulses via the ICM.
Doc
Dear God......................
Doc
Drink 12 and then go play on the roof.............................
Doc
How about a new marvel approach?
The fuse in question is fed by a fusible link, either on the firewall on a bulkhead connector. Made of a bakelite type material, or on the starter main lug, where the battery plus cable goes.
My bet after you said you juiced the fuse is that, the fusible link is toaster, not connected or broken!
Refinish King
Hey Elliot, Hope you have a good move to your new place. We'll see you when you get back.
nospam
Ran/leaked 10 Gal of gas through it in 12 hours today. Requires the AB diagnostic jumper to run, and it keeps flashing the
12... According to Haynes, the Probable cause is: "... no reference pulses from the distributor are reaching the ECM". That makes good sense why it would shut off within 2 seconds too (w/o the diagnostic jumper). Guess that's something else to look for rather than throwing a new computer at it. Meanwhile, it runs and it can move itself onto the car-hauler for moving. Also, Haynes has the OBD1 pin out on the adjacent page:A Ground B Diagnostic Terminal C Air (if Used) D Check Engine Light (if Used) E Serial Data F TCC (if used) {what is TCC?} G Fuel pump (if used) H Brake sense speed input M Serial data (4-cyl engine only)
Elliott
You were so amazed it started that you didn't want to shut it off? WTF is the point of letting it run for 12 hours? Bob
Crank position sensor:
Or ignition module. But, if it were the ignition module. It would kill the injector pulses too.
Refinish King
Probably just run in time, to see if anything was going to break that he missed - as he "rebuilt" the engine. Dunno how many times I've fixed something, just lightly used it - or didn't use all of its functions, and had to take it all apart again when something was wrong. Last thing like that was when I installed a stereo in my 1990 GMC Jimmy.
~KJ~
If you have a scope handy, put it on the purple/wht. It's the reference pulse to the computer from the distributor. blk/red is ground, wht is the signal back to the dist, tan/blk is the timing set/ign bypass. You should get a series of square pulses, 12v, about 50 msecs apart at idle, IIRC. It's 6 per revolution on the six cylinder. You will get a signal since the truck actually runs. Your injectors cant fire without the signal coming in.
Now, if you're ready to actually fix the problem start with the computer. There are battery inputs on terminals B1 and C16, and ignition input on terminal A6. Disconnect the computer, hook up the battery, turn the key on, and make sure you have 12 volts at these terminals. Use a test light to make sure that the wire can actually carry some current and isn't just holding on by a strand or two. grounds on A12, B3, D1, and D6.
BTW, did you fix the orange wire yet? It's the one that brings power in on B1 and C16.
Do you really think this engine has a crank position sensor? I didn't see one, and it has a distributor - so I'm not sure that would do it (can you elaborate - and describe where it would be?). It's not shown on the Haynes schematics either (even for the 92/newer). And I didn't notice one on the bell housing.
The Haynes 92/newer schematic shows the Distributtor pin-out (IC, Ref-Hi, IGN BY, Ref-Lo, I wrote these onto the other schematic too). Anyway, does anybody know the what that means in terms of wave forms?
And on the other-stuff, the 2nd gas line is now new, the gas-tank ground is solid (clamped on) now, and I took it for a ride... Thankfully it shifts ok - though the 4 wheel drive doesn't seem to be working. 4-L goes into a low gear mode, but it didn't seem like I had 4 wheels going up the grassy slope (had to back down).
Of coarse it's gutless w/o getting it into closed loop mode. The 88 was the same way until replacing some of the sensors and the fuel pump.
Elliott
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