Oh boy where do I start? Starting problems!!

[stash3123]

Ok so I am having some major starting problems. I have a 90 GA LE with the quad 4. When I try and start it whether hot or cold it is hit or miss whether it will catch. Most of the time it's a looong start. There is no consistency though. Sometimes it starts right up but more often than not it's that long crank before it starts. When it does start it has a ridiculously rough idle and feels like it's about to stall, and sometimes it does. But once I get past all that it runs strong, it's just when I start up. I have changed the fuel filter (which was clogged), fuel pump (which was pretty much dead), plugs (completely black), map sensor, did an oil change, and checked the air filter. I also found a broken vacuum hose. All this and I am pretty much no better than when I started. The car is also running really rich. I failed my emissions inspection for Hydrocarbons. I passed all the other categories though. Does anyone have any clue what else I should look for or change? Thanks in advance.

[Blackhawk]

Did you check your FPR? I'm guessing you threw no codes, which doesn;t surprise me because it's a fuel related problem. The iffy starts and the rough idle tells me that you're not getting fuel to the engine and at the same time you have a vacuum leak.
Find your fuel pressure regulator, and take the vacuum hose off the top CAREFULLY, you don't want to break it. Smell into the hose, and if it has a strong gas smell, replace the FPR. It's anywhere from $50-100 depending on where you shop, my local NAPA was very expensive for the part.
It doesn't take long to do, and is a night and day difference. If you don't smell a gassy odor, Rick will be in later and he's a hell of a lot smarter than me on this stuff.

[00gagt]

how old are the o2 sencors

[rixGAphx]

Originally posted by stash
...once I get past all that it runs strong, it's just when I start up. Are you saying it runs AND idles OK once the engine has warmed up?
Or does it idle rough all the time?
Originally posted by Blackhawk
Rick will be in later and he's a hell of a lot smarter than me on this stuff. Thanks!!
Mostly that's because I'm 3 times your age and have made 30 times as many mistakes :D

I think you're on the right track, that it's a fault in the fuel system.
And since he's replaced nearly every OTHER fuel-related component, FPR makes sense.

If it were a faulty FPR, either on the low-pressure/idle circuit (with the diaphragm and gassy smell) or on the high-pressure/higher rpm circuit (like a broken spring or damaged seat), then I would expect the problem to be there at idle throughout the day, not just at start-up.

I'm pretty sure he's running ultra-rich at start-up, which argues against most true vac leaks (though argues FOR the leaky 'vac' diaphragm in the FPR).
I'm thinking one or more injectors is stuck open, or at least is prevented from closing fully by a microscopic grain of sand lodged in the spray orifice, preventing the needle from seating nicely.
* When the engine is 'off', the pressure in the rail 'bleeds-down' thru the injector(s), dumping a sh!tload of gasoline into the intake runner(s).
* When the engine is cranked, the other injectors have to wait a few seconds for pressure to build so they can 'squirt'.
* Meantime, the gas-filled runners (at the leaky injector(s)) are producing an air-fuel mixture so rich it can't possibly be ignited ('flooding' was the term back in the carburetor days).
* As more air gets sucked-over the gasoline puddle in the runner(s), the gas evaporates and the engine gets happier.
* Driving around, the leaking injector(s) aren't leaking so much as to cause even idle problems, and they are heavily disguised at higher rpm (or even eliminated as the O2 sensor figures out what's happening and the PCM adjusts the injection pulsing accordingly).
* * *
A 17-yr old car, with who knows how many miles or work on the injectors, as well as the rest of the engine.

First, I would run a couple bottles of name-brand off-the-shelf Fuel Injector cleaner thru the tank, according to bottle directions.

Next, if that didn't work I would price-out a set of 4 replacement rebuilt injectors; they're pretty easy to replace on the quad IIRC.

I would compare the cost of rebuilt injectors to a cost of professional cleaning of the injectors (they use the same chemicals as in the DIY bottle, but force it thru under greater pressure than the fuel pump can).
This *might* dislodge the microscopic grain(s) that are *prolly* causing the injector(s) to stay open.

So: Bad FPR if the rough idle exists all day long, leaky injector if the problem is only at start-up.

Good luck,
-Rick

PS:
Couple years ago, the #2 injector (right, forward-facing) on my V6 stuck open.
So badly the engine would barely run at highway speeds and I pulled-off to the shoulder.
Let the car cool, calmed myself down, didn't know what was happening.
Tried cranking the engine, wouldn't even turn, much less fire.
Opened hood, removed 2 plug.
Sat in seat and turned key to 'start'.
Gasoline SPRAYED out of that plug hole like a garden hose sprayer!!!
Holy Sh1at!! Good thing nobody threw a cigarette butt, or we'd have had a flame-throwing GA!!

There had been SO MUCH liquid gasoline, dribbled from that injector down into the #2 cylinder, that the engine had actually hydrolocked.

[Blackhawk]

I don't remember mine idling too weird after being driven for a bit in most cases. Who knows though, I don't have a great memory for something I don't need/want to remember.

[stash3123]

Thanks so much everyone. It was the FPR. The car runs like it's brand new off the dealer floor. Between changing the FPR and everything else I listed that I changed in my original post it feels awesome. I really appreciate the help.