Taking one last stab at killing my 3.1 hesitation

[IanSzgatti]

good thing you got in there... im saying 65% chance you've found the problem. while the o-rings might have been all brittle and junk, the 'crud' could still have been making a seal... if not, you've found your source of unmetered air. The PCV being blocked off could also add to your problem or create it depending on how badly it was blocked... by the time I finish this paragraph my percentage rate will have gone up to 85% sure...haha... good luck mang

[toadson]

After snapping a plenum bolt, breaking an ez-out, and breaking numerous drillbits, I got the car back together last night. I must say I was in a pretty crappy mood after wasting all the time trying to get the bolt out. After I got it all back together, the hesitation is still there (big suprise). I drove the car 120 miles today, and it doesnt seem to be as bad as it usually is. I did manage to find a 1990 Lumina remanufactured ecm at the junkyard today, so that will be my project tonight. I also noticed my clutch pedal isnt returning all the way, letting my clutch slip under a heavy load. Oh the joys of owning a Fiero....

[IanSzgatti]

A PCM?? at what point do you look toward the fuel pump?

[3XTurboAgain]

Im pretty sure just because the injectors ohm out, doesnt mean they arent clogged.. good luck.

[toadson]

The new ECM changed nothing, so I'm going to pull the wiring harness from my car tonight. I'm going to double check every splice I made, and maybe just resolder each one. Im also going to look at each pin on the connectors for the ECM, just to make sure they are all tight.

[toadson]

I finally finished re-doing the wiring on the Fiero. About the only things I've found were a loose EGR wire and ground wire on the ECM connector, and a loose connector going to the fuel pump relay. I got another knock sensor and connector which I installed as well. The wiring looks much better than it did before, so I at least got something out of it. The hesitation is still there just as it was before. I havent gotten the chance to scan it yet, so I dont know if anything has changed that I haven't noticed. About the only thing left to check is the fuel pump itself, but I have a feeling that's not the problem either.

[IanSzgatti]

About the only thing left to check is the fuel pump itself

the fuel pump itself

fuel pump

[toadson]

Are you trying to hint at something? Hahahaha

[toadson]

Fuel pressure seems good. I turned the key on, pressure went to 41 PSI, then slowly leaked down to 37 where it stayed. Took it for a spin and the pressure would shoot up with each tap of the throttle. Cruising it would be around 40 PSI, and would shoot up to 45-50 PSI when I gave it gas. I hit a huge pothole on a background, and somehow my alternator cut into my coolant hose, so I didnt get to mess with it for long. Now I gotta find a new hose before it gets back on the road. Pressure as of right now though, with the car shut off, is 48PSI, with no leaking. If I remember right, I left the pulsator on the fuel pump when I installed it, and I wonder if it could be causing problems. If that were the case, I would think the pressure would leak off rather quickly, but who knows.

[toadson]

I dropped the gas tank tonight and I might be onto something..... The inside of the tank is pretty rusty, and my town recently switched to 10% ethanol gas this summer. My dad mentioned that ethanol gas will clean rust off the inside of the tank, and it is doing exactly that. The fuel filter I changed a few months ago had a bunch of dark gas in it, and so does my new one that I checked tonight. The fuel pump sock is rusty colored, theres rust floating in the gas tank.... so yeah. Im sure this isnt helping things, so Im going to clean the inside of the tank with muratic acid. The stuff works great, as I cleaned out my old Kawasaki KZ1000 tank with it once before. Ill let you know how it turns out.

[IanSzgatti]

sounds promising...

[toadson]

For once I turned out to be right! The hesitation is gone! http://www.fiero.nl/forum/Forum1/HTML/067616.html
Check it out, Im so glad I finally figured it out. Thanks a bunch for your help!

[IanSzgatti]

good work... i honestly was only kidding and never would have suspected a fuel related problem... i thought low tire pressure, or you needed some oxygen in your headlights!

[3XTurboAgain]

Congrats!!!!

[IsaacHayes]

Nice! Feels good to be running smooth again eh?

E10 is nasty stuff. Everyone thinks ethanol is so great, but it's not that great really. And it costs me taxes where I live as the state vehicles run on E85 which costs more (less mpg ends up costing more, and we pay incentives for the people to actually refine the stuff because otherwise they would loose money making it. Oh and then grains go up and so does the cost of milk, and meats because of that...).