Throttle tip in hesitation

[DEI37]

OK...did some diagnosis tonight, and came up with this. Spark, is good. Valvetrain operation, good. Fuel pressure, good...41psi, engine off, key on. During crank, it is still 39psi. Those numbers are in spec. I ran the overflow hose from the pressure guage down to a fuel can, and there is a lot coming out...I don't know how much I should have, but I would think that volume is there, too. The fuel pump is loud, and all that, but my dad told me it's always been like that. The filter was changed less than a year ago. I'm starting to get pissed. I can't afford a problem, and I do konw that there is a clunk in the right front corner that I need to look in to a little further, too.

HHHHHEEEEEEEEEELLLLLLLLLPPPPPPPPPPPP

[slowbird]

So you have all good wires, coils, and plugs?
And the fuel pump, filter, pressure and injectors are good?

What's it doing exactly when you try and turn it over?

[DEI37]

Well, now it's to the point where it's not "catching" much any more, but it will backfire through the exhaust still, some. When it was "catching," it's like the engine had seized, but if you kept the key turned, and juice to the starter, after about a second or so, it would turn over again, albeit with some backfiring. I'm being told that it could be flooded? It is cold here, and I don't doubt for a minute that it did flood, but I just thought that after 24 hours, it should be OK. They told me to pull the plugs out of it, and let it dry out. Hope that answers some of your questions, and can give me guidance here. Thanks!

[DEI37]

No-start continuation...more info, tests to run...need info

My dad talked with a GM tech today on this subject, and he said that the ICM controls spark timing, and when I introduced the radiator fan and radiator in to the ignition sequence, may have thrown the ICM out of whack. There is spark to all six cylinders. But, of course, if the spark timing is wrong, we'll have a no-start/run issue. And, backfiring is tell-tale of timing gone wrong, correct? He said to start by ohming out the coil packs, and seeing what is what. What values do I look for, and will this method work? I would think that the coils have to be fine, but the ICM could be done for, right? I think the ECM is OK.

One other thing I noticed was that I pulled the fuel pump relay to prevent further fuel introduction to the combustion chambers. Fuel pump still runs. What gives? Thanks. You guys have been patient and informative thus far...please...I beg you...keep it up!

[SappySE107]

I was going to say the ICM or the CPS, or the wiring between the 2. It definetly sounds like a timing issue. Unless all the coils went bad...I doubt they are your problem.

[DEI37]

OK...with you saying that, I'll lean towards the ICM, because there would be NO spark if the CPS took a shit, correct? Well, now I have a better idea of what to look for...hopefully, they aren't much money, because I know they are a pain in the butt to R&R.

[SappySE107]

Hahaha, they are too damn much brand new. I sold one with coil packs to ridgerunner, and his old one wasn't the problem. You can see if he would sell it, or check ebay. There may be some on there for a decent price.

The CPS would probably cause a no spark condition, or intermittent. If you get a consistant spark, its probably not that or the wire.

[DEI37]

OK...did some more digging tonight, and went back to install the front bank of spark plugs, after letting things dry out from fuel. Was reintalling everything, and noticed that the #6 wire wasn't right...again. Unfortunatly, neither was #4. Yup...you guessed it. I crossed them somehow. I will STILL swear that I never had more than one wire off at a time, but apparently I did, and it bit me. It runs now, but still has that pesky hesitation. I'll look in to slowbird's advice. Also the clunk in the right front appears to be either a strut or a upper strut mount. Thanks for the input that y'all had...glad this was a cheap fix. I love those.

[DEI37]

Never mind...it's dead again.

[WhiteMonteZZZ]

For what it's worth, my 95 DOHC has always had a tip-in hesitation (albeit a very small one), and after new tps, iac, plugs, wires, amongst other things, it's still there. Hope you get her runnin right though....

WMZZZ

[DEI37]

I think I'm gonna head it off to junkyard heaven. It runs at night...usually. Very well, too. But, when I need it to go, it doesn't. It gets my hopes up, and then kills them. I have good money in this thing now...water pump, brakes, tires...have treated it well. It's screwing me over. Got a couple more tests to do...again...may still be fuel delivery, just that it's too much. Possible FPR, allowing too much, and it's killing itself, or leaking injectors.