1991 Camry Intermittent No Start

[Hildy]

I posted this in the Camry section, but now it looks like maybe i should have posted it here, anyways

Hey guys, first post here so hello all! Well here goes.

It is a 1991 Camry 4cyl, electronic auto tranny, 131k. Car had been towed into our shop a couple times for an intermittent no start (couple months apart), and started everytime it got to our shop. I finally snapped a waveform view of the fuel pump, and it was nasty, so we replaced the pump on a recommendation. Car was fine for about 6 - 7 months and then it came back, again, this time as an intermittent stall when running then no restart, of course starting every time we seen it. Only recently did it get to the point where it died completely. I went to the customers house to diagnose it, as i love diagnosing no starts, and didn't want anything to jiggle around on the tow truck. It had solid spark, jumping my 30kv gap, and beautiful injector pulse, as well the tach was fluttering and great fuel pressure. It did not, (and never has had) any codes, and the car was turning over like a champ. So i got it towed back to the shop.

(I am going to apologize right now for such a long post, but U have more hours into this car than i care to admin, and i don't like to get beat)

So of course it starts when i get back to the shop, runs great, several test drives, and nothing. After about a week, no start, so right away i double verify spark and injector pulse, both there, both great. Car sounds great when it turns over, but then i notice it wants to try to run backwards, only when you turn the key back from crank to run. I can turn it over for 2 min, or 2 secs, but only when i let the key come back from crank to run does it do this. So im thinking great! Easy! Timing!. So i check: Timing belt marks, Verify TDC with 0 on crank pulley, and verify rotor movement in distributor. All Great ( I did double check timing when running as well and it was in spec). Then it starts again so i have to wait another week before it no-starts.

SOOOO it no starts again and i scratch my head, kind of repeating all my previous steps, as it had been a week, and my memory was a little vague. I decide, what the hell, lets take a sample of the fuel and put it in a bowl. Did this and, waddya know, WATER in the fuel (lots), so now i am excited! Drain tank by pulling backseat and sucking dry, change fuel filter (which was almost plugged with dirt, yet tank was spotless), add some new gas and methyl hydrate for good measure, and cross my fingers, runs for another couple days, no start in the morning again. It seems to be getting worse. When it does fire and run, it seems to have a lean stumble when you accelerate the motor quickly, but fine if you load it slowly.

So here is a list of things i have checked and verified as good/working

1. TPS checked and Adjusted (IDL s/w was mis-adjusted)
2. ECT checked and verified as same voltage and resistance as IAT in MAF
on a cold morning
3. IAT - mentioned above
4. VAF, checked for smooth movement as well as no drop outs or glitches,
voltage at KOEO was around .6v IIRC
5. CKP, CMP, IGT, and IGF signals at both ECM and Igniter
-Note, i was getting 5v flatline on IGF at one point and no spark, but i am not sure if i induced this somehow, as i have had spark the rest of the time it has not started.

6. Timing (Belt and Distributor)
7. Fuel pressure - a tad on the high side by about 3-5 psi, but seemed ok
8. Spark and injector pulse, at the same time
9. All power and grounds at ECM and sensors. Voltage drops at grounds are about .07v, goes up to .12v when cranking, back to .07 when running.
10. I even watched my o2 signal during a drive, and it seemed to function quite normal
11. Wiggle tested every wire in the car about a billion times
12. Compression test - 180 across the board
13. Pulse width on injectors - 15 ms during crank, 65 fahrenheit, cold no start, about 8-10 ms during crank on warm start, 2 ms at idle

I am sure there is more, but i have forgotten at this point. So I am stuck right now. I am assuming that because i have good IGT signal to my igniter that my CKP CMP and ECM are functioning OK. Since i have injector pulse and Fuel pressure, i am assuming i have fuel at the cylinders. I dont think that 15ms pulse width during crank is enough to flood it (?) And dont tell anyone, but i even pulled a vacuum cap and sprayed some staring fluid into the car, to see if it was a lack of fuel, which did nothing as well.

One last thing, it only seems to up the pulse width to 6 ms when i snap the throttle quickly, no matter if i snap to 1/4 throttle, or snap to full throttle - this seems odd to me, but then again i have never actually checked pulse width on a camry

So tomorrow morning i am getting up a couple hours early to hopefully catch the car no starting again, and try to narrow this down once and for all. I will let you guys know how it goes, and if you have any ideas, any at all, feel free to let me know,

very much appreciated,
one very frustrated,
-Jason