Well, I'll swap the tachs out tonight then. I don't know where my multimeter went so I'll have to pick up another and see what I can figure out. The trouble is that the problem goes away and the car can start again faster than I can take the dizzy apart and set up a multimeter

Anyway, here is what the old air canister looked like. Lots of rust and a rather large hole on the bottom of the lip that I never noticed. I wonder if thats been the cause of my intermittent code 44? Hmmm...

re - fuel in the lines turning to vapor. The fuel pressure regulator is located on the fuel rail. The tank mounted pump is supposed to be able to generate about 60psi. The regulator is set for 45(ish) psi minus intake vacuum. The regulator releases the excess presssure into the return line and the fuel is returned back to the tank. This acomplishes two things. 1 - The pressure differential between the fuel side and the intake side of the fuel injector is held constant. 2 - The return of excess fuel has the effect of cooling the fuel rail while also eliminating any vaporized fuel pockets that might have occured.

If your fuel pump isn't able to produce a pressure that is over the regulator pressure then no fuel is returned and vaporlock can be a problem. Blocking off the rubber return line with a vicegrips allows you to see the full pressure that your fuel pump can obtain.

How do I bypass the regulator to test the pressure at the lines? By unscrewing them from the rail and directly to the tester?

So thinking about this - what could "cool down" enough in 1 min or so to really make a difference? Nothing that I can think of. How about this - Something is either blocking your fuel pick up, or blocking your fuel filter. When whatever it is works its way to block the flow, when you shut down it takes a while for it to release.

This would cause a sputtering type cutoff, and it would also cause a code 44.

So fuel filter or a crappy pump or just crap in the tank?

The car did sit in a field for about 8 years before I got it. When I did, I replaced the filter, pulled the tank and dumped the old gas, and put in a new pump. I could just dump 2-3 bottles of Chevron Techron in and see what happens? Unless the fuel strainer or the filter is already full of old crap or something.

All the temp sensors (MAT (aka Air Charge Temp), Coolant Temperature Sensor (for the ECM), and Temp Gauge Sending Unit all can be checked by reading their resistance and comparing them to this chart

https://www.fiero.nl/forum/Forum2/HTML/107560.html

Oh, now I know what you mean about clamping the line. Ok, I have a good pair of vice grips with flat pads on them that would do just fine for that. So things to do tonight:

-swap tachs
-check fuel pressure with return line clamped via vice grips
-pick up a couple bottles of injector cleaner and dump in the tank
-replace fuel filter (maybe?)

I'm only speculating what could be the trouble. Hard to say without making a reading of fuel pressure while the problem is happening. Might be worth a fuel filter and rail mounted pressure gauge.

Yep

[This message has been edited by phonedawgz (edited 07-28-2010).]

Ok, I'll check the AM MAT after I get a new multimeter.

If I could give out more than one + I would have given you like a dozen by now I'm pretty mechanically inclined but I'm no mechanic either and I'm only 23 so I don't have much experience hunting down problems. When I get stumped, I really get stumped so its really nice to have someone to bounce ideas off of.

A fuel filter is all of $10 so its worth a shot at least. Pretty simple to change out on the Fiero too by the time I roll the rear end up on some ramps.

I'm not going to hurt anything by doubling or tripling the recommended dosage of injector cleaner am I? Possibly foul up the O2?

I wish I had a way to watch the fuel pressure in real time. If the motor was in the front I could use the tester and just remove the hood and tape the gauge where I could read it somewhere. Although I know someone who did that, it leaked, and their just-restored-with-less-than-10-miles car burned to the ground...

[This message has been edited by Alibi (edited 07-28-2010).]

This is a fairly tough problem to troubleshoot. If the damn thing just didn't run it would be much easier. Your troubleshooting has been pretty good from what I see. You eliminate possibilities, evaluate symptoms and suggest possible failures.

idk on the injector cleaner - see what it says on it. I wouldn't put more in then they recommend.

[This message has been edited by phonedawgz (edited 07-28-2010).]

Ugh, intermittent issues like this are always the hardest to fix

I've been fiddling with old cars since I was about 17 mainly because I didn't have a choice. It was either fix the beater or not make it to school and work. Over time I just got better at it

I'll just get the "treats 10-25 gallons" bottle of Chevron Techron then. It probably needs some ran through it anyway. Techron and Lucas make the only injector cleaners that I actually trust to do what the bottle says it does. Oh, and Seafoam but it does wonders with everything

[This message has been edited by Alibi (edited 07-28-2010).]

Wouldn't hurt to carry a good sized fire extinusher with you while your messing with the fuel stuff. I wouldn't keep it in the trunk.

I've got an extinguisher thats about the size of a 2-liter soda bottle in my front trunk area. I could pull the really big one out of the house and have it with me too. Too much of a good thing never hurt anyone.

Made some progress.

I replaced the fuel filter. The old one, although its only got 5000 miles worth of use, tops, though it was pretty nasty inside. Lots of black chunks and when I tried to blow through it it took a LOT of effort to do so. So yeah, it was plugged up pretty bad. I'm really thinking this may have been the cause of it. I doubt I got all the crap out of the tank when I dumped it a year ago but I know I at least put in a new filter. I bet whatever crap made it through the filter sock on the pump clogged up the filter in a hurry. I think changing this filter with my next oil change would be a good idea to check on the amount of crap in the filter.

I then tried the fuel pressure. With the return line clamped shut and the pump turned on to prime I got about 95 PSI. PLENTY of pressure there! It fairly quickly dropped pressure to around 50 and then its then slowly bleeds down. It used to bleed down rather quickly but I think that was caused by a lack of vacuum in the regulator from a vac leak in my cruise can.

With the line unclamped I get about 39-40 PSI of pressure which then slowly bleeds down. Its a tad on the low side but I think its still acceptable considering the 95 PSI pressure when clamped. Maybe I have a weak regulator, but not enough to hurt anything?

Next I'm going to swap out the tach, put up tools, go for a ride, take a shower to get rid of the gas smell, and go to bed. I've got a bottle of Chevron Techron that treats "up to 20 gallons" so I think I'll dump that into my tank on my next fill up.

Once you start your engine, the fuel pressure should drop by the amount of vacuum in the intake manifold. The fuel pressure regulator has a vacuum line attached to it, and is designed to hold a constant pressure differential between the pressurized fuel rail side of the injector, and the other side located in the intake manifold. So once you start your engine, the fuel pressure should drop about 10 psi. Not dropping the 10-12 psi might be caused by a disconnected vacuum line to the fuel regulator.

Seems to me that your stalling issue is entirely heat related. This would immediately lead me towards the sensors/electronics and away from the fuel system. Also would need to find out if there is added heat from a lean condition. O2 and Fuel intergrator readings from your scanner will give you a very good indication of your A/F mix.

It seems your car is getting hot enough to cause faults in the system. The items that come to mind for me are the ICM, pick up coil, ignition coil, fuel pump relay, and ECM CTS. All 5 of these items can cause issues when overheated but they can also be easily tested to determine if they are working properly.

Were you ever able to verify the ECM CTS temps as being right? I know its newer but that doesn't mean it working perfectly. The multimeter test should tell you within a few degrees how close it is. The reason this one keeps coming to mind is it has been common problem for me on several cars, including fieros, and there seems to be a higher probably to fail in this way. If the CTS reads 260+ when the car is at 220 the ECM will kill the engine. Thats a difference of only 75ohms resistance at the sensor. Not very much. When temps creap up I usually notice some sputtering before full shutdown I suspect from small variations in coolant temp as it flows past the sensor.

Fix your code 44 however you can. Its not helping your problem. Check for vac leaks everywhere, check exhaust manifolds for cracks/broken studs, ect.

EDIT: On your EGR valve. Since it seems you believe its bad it could also be contributing to your issues. A common emissions problem is high NOX. This is usually due to an increase in combustion chamber temps above 2500F and is usually caused by a faulty EGR valve or EGR solenoid stuck open (solenoid would set a code though). It could easily add the extra heat you are seeing. EGR valves recycle exhaust gases back into the intake manifold under certain conditions to dilute the a/f mix with inert gases, as c-chamber temps rise the recycled exhaust temps also increase. It creates a nasty cycle. If it gets bad enough it can also cause misfire/pre-ignition. If its leaking it could also cause your code 44. A scanner looking at O2 and fuel intergrator values may give a clue.

[This message has been edited by Fieroseverywhere (edited 07-29-2010).]

I still haven't checked the CTS. I'll be going through Joplin today where there is a Harbor Freight and I'll pick up a cheap multimeter there.

I've borrowed a party fogger and a jug of fog juice so I'm going to somehow rig it into an engine fogger to see if it will show any leaks in my vacuum or exhaust systems. I just need to rig up some kind of hose.

On the EGR, I just don't trust the aftermarket unit I got from Autozone. I have what appears to be a good OEM valve laying around so I may just swap it in just for the heck of it.

I was thinking last night that if the fuel filter was getting clogged up that it would happen at night as well as during the day, so that still leads me back to a heat issue caused by the lean condition which is caused by who knows at this point. I just have to go through everything and in the mean time still have to use my car to go places. Ugh.

Did you get the tach working?

If the tach isn't working leave the tach filter disconnected.

No, I was too tired to swap the tach out last night. I'll probably get it in tonight though.

Made a few interesting changes.

I was suspecting the aftermarket EGR was less than perfect so I replaced it with an OEM EGR. I at first didn't use a new gasket but I blew out the old one so I had to buy a new one.

I also replaced some spliced vacuum lines with better fittings and bits of hard line.

While I was at it I replaced the 195 T stat with a 180* T stat.

I drove it tonight and it ran smoother than it ever has and I didn't have any stuttering after the ECM had time to re-learn. Instead of my temp gauge reading at 220 or just a hair above it, I was just a hair below 220. It wasn't significantly cooler out tonight either, so I did something right

I tried my other tach but it doesn't work either. The needle does pulse when I turn over the engine so that at least means the pick-up coil is good, right? I did learn that my pick up coil is a cheapy that the rebuilders used on my new-style distributor. At some point the wires got pinched under the dizzy cap too so I may go ahead and swap the PU coil out with a nicer one if that sounds like it makes sense?

I'm also considering relocating my coil somewhere else in my engine bay to get it away from the hot manifolds (maybe next to the C500 since my battery is up front now) and maybe go ahead and buy a heat sink kit from Dawg for the ICM just in case. I'm really getting sick of this failing electronics problem...

Arrrgh, stalled out yet again. I drove it about 30 miles into Joplin to go over to Mike's place (another fiero guy, SilentAssassin) to pick up a few parts I had loaned him for troubleshooting on his 3800. We talked for maybe 30 minutes and then I left to go get something to eat accross town. After I get accross town the motor decides to stall out on me at a stop light. Luckily no one was behind me so I just sat through a cycle of the light and the car fired up just in time for the light to turn green again.

I parked it, ate a sandwich, came out and drove it around town the rest of the evening without any trouble.

Best I can tell is that while I was talking at Mike's the engine bay heat was enough to soak into the electronics as there wasn't any fresh air moving through the car to expel them. By the time I had drove to the sandwich shop the additional driving heat was enough to make my electronics fail.

I bought some 1x1 angle iron that I'm going to turn into a bracket to mount a coil in the old battery tray (battery located up front) to get it away from the exhaust manifolds. I'm really thinking that my header wrap on my crossover just isn't enough to keep the hot exhaust air from overheating my electronics. If relocating the coil doesn't work then I'll either look into relocating the ICM or getting a heat sink kit for it. I'd really like to get some proper heat shields for the Y pipe though.

I dropped by an O'reilly in Joplin and one of the guys told me to try cutting up some foil turkey pans and use those for makeshift head shields so I've got some foil between my Y pipe and the dizzy/coil area. Maybe it'll help? Dunno. I need to reset my computer and see if I'm still getting the code 44.

Your stalling when hot sounds hauntingly familiar...

I had this happen to me off and on for a year or so then something changed for the worse and it started happening all the time after the car had been driven far enough to warm up. It turned out to be the rust and corrosion in the fuel tank that clogged the strainer and fouled the fuel pump. One of the clues is when I changed the fuel filter and it had lots of gunk in it and it had only been on the car for a couple of thousand miles. Pulling the tank, cleaning the piss outa the tank (cleaned it much better this time) and putting another new pump and strainer in fixed the problem. As phonedawgs has suggested, it was vapor locking when hot. I had the same symptoms, it would buck and stall. I would continue rolling straight, turn off the key for about 10 to 20 seconds and then turn the key back to on. The car would sometimes start running as if nothing was ever wrong and sometimes it would continue to run rough or stall. Because of what you found in your fuel filter I would stop the BS, drop the tank, clean it correctly and put a new pump and strainer on. It's a pita but from what you saw, you got issues in there.

Charlie

[This message has been edited by cptsnoopy (edited 08-03-2010).]

I'm really hoping its not the tank full of crap... if I get a new pump and drop it, whats the best way to clean out the tank?

Drop the t ank. Rinse all the heavy solid objects out with a high pressure hose . Repeat if nescessary. Make sure all the contaniments are out and then acid wash it. Fill it up half way with water then pour muratic acid in it quantity of amount is your choice but I would say a quart or so. After an hour or so of sloshing around then dump baking soda in it to neutralize before dumping out. Dump out then rinse it again to ensure it is clean. I would then get the POR-15 restoration kit and follow the directions from there.

[This message has been edited by gmctyphoon1992 (edited 08-03-2010).]

I'm pretty limited on what I can do in my back yard... I don't even have a water hose

I had read on some other threads after searching that dumping some laquer thinner and sloshing it around would help dissolve any crud/varnish. I'm debating on what to do though. I should go ahead and drop the tank while the car is still running so that I can run the fuel tank down close to empty and drive it up onto ramps with its own power. I'm just not looking forward to doing it is all.

I've got a friend with a lift so I may ask him if I can borrow it, but first I need to pick up a fuel pump if this is indeed what needs to be done.

You can go to a self carwash and atleast rinse the tankout after you take it out of the car worse case senario cause you want to atleast get the big chunks out. I don't think I would use laquer thinner because it might compromise the walls of the tank but I am not 100 percent sure

[This message has been edited by gmctyphoon1992 (edited 08-03-2010).]

I just got off the phone with a friend of mine. His dad has a full shop with a lift that I can borrow so I'm going to head over there probably Thursday and go ahead and put a new pump in. The town has a car wash but the trouble with that would be getting all the water out afterwards. I'm pretty sure laquer thinner or even acetone would work OK to swish out all the crap that may be in the tank.

After I failed miserably trying to clean the tank the first time I changed the pump (just rinsed it out good) I decided to try something a little more aggressive the second time around (this was when my car was stalling when hot). I bought a bottle of BB's, I am pretty sure it had 1400 BB's in the bottle. After rising the tank with water and letting it dry out I poured the BB's in and then shook the Hell out of it in every direction for a total shake time of about 15 minutes. It took about an hour because I am getting old and I could only shake it good for a couple of minutes at a time. Then when I finished that I removed the tape that was over the holes and poured out the BB's the best I could. I tried to see how much crud was broken loose but it was such a mess that I gave up after putting about 2 cups of rust powder and corrosion chunks in a bag. I was amazed at how much crud was actually in there. I then vacuumed it out dry for awhile but that did not get all of the rust powder so I rinsed it out the best I could and then used the wet/dry vac to try and get the rest. It was a lot cleaner than the first attempt a couple of years ago but I bet that because I did not coat the tank with something like the por-15 system it is probably still corroding in there. It should last a while longer though before I start having problems again. This was around a year ago that I cleaned it out and the car has been running great since. (86GT/auto with an 88 yellow base coupe body on it). I did the same thing with my project car, I hope it does not foul up from corrosion before I get it painted...

Good luck with yours

Charlie

BB's? Would there be an problems if all of them couldn't be removed? My little brother used wood screws one time in a motorcycle gas tank but I don't think they would work too great in a tank with a baffle. I've also read that pea gravel works too.

the bb's probably won't do much unless it gets sucked up into the pump than you might have a problem. It could possibly freeze the pump burning it up or clog the pump. If it gets passed that than it could possibly clog the lines or fuel rail and maybe one of the injectors. The filter would prevent that though and I am pretty sure there is a mesh peice over the pick up tube on the pump. It was on mine atleast.

Ordered a Delphi pump and strainer from NAPA. It'll be in tomorrow so I'll be heading to my friends shop to replace it. I'll try to remember to grab my camera to get some shots of inside the tank if I can. Hopefully its full of crap and that will be the end of my troubles after I clean it out with the jug of Laquer thinner I bought

It occurred to me that if you found sizable solid chunks in your fuel filter then either your pump strainer has a hole in it or the steel line between the outlet of the pump and the filter had some chunks in it. I suppose some parts of the pump could have let go too but I think that is pretty unlikely. I have to admit I was relieved after finding my fuel filter full of crud and that the strainer looked the same. By the time I dropped my tank the pump was starting to fail hence the drop in performance from running ok and stalling when hot once in awhile to being hard to start and stalling and bucking with poor performance. Cleaning the tank and replacing the pump and filters is a pita but if it fixes you problems, it is a beautiful thing...

Charlie

Dropped the tank today. Was pretty easy with a lift so it went pretty quick. The old pump strainer had some debris on it but not much and the tank itself had some sediment and sand-like stuff but nothing bad. I went ahead and swooshed some laquer thinner out and dumped a bunch of orange crap out of the tank, probably some rust and varnish. Swished it again and it came out pretty much clear.

I went ahead and hooked the pump up to a 12V source and it would spin up just fine so the pump very well may have been good. Then again, I couldn't really hear it when it primed in the tank anymore like I used to.

Something else, when I primed the pump, turned the key to off and then right to on again it wouldn't prime again. Is it supposed to? When I turn the key to off, pull out my key, then key back in and then on it'll prime. Is that normal, or is it just that the action of removing the key allows the fuel rail to de-pressurize enough that the fuel pump will prime again when I turn the key back to ON?

I had a mechanic friend of my friend helping me switch tanks and he was wondering if there was a secondary relay or switch for the pump that shuts the pump off in the event of a wreck. He is wondering if something like that could overheat and cause the pump the shut off? Otherwise he's as stumped as I am...

I'm going to go ahead and relocate the coil tomorrow anyway. I'm going to put it right behind the vapor canister out of the way of the heat coming up from the trunk-side manifold and Y pipe. The mechanic friend said the header-wrapped Y pipe should be just as good as the factory heat shields in preventing heat soak but I still want to find a set of factory shields to put on over the wrap as a second layer of protection.

If the car still stalls after this then I'm going to burn it. j/k (maybe?)

My car primes the same way. If I prime it, I have to wait a little bit before I attempt it again or it does not prime. Don't know if it is normal but at least two of us have the same results. One of the things I considered is that the crud in the tank can be sucked onto the strainer when the pump is running and cause the strainer to clog up until the pump is turned off, then the loose crud might just float away in the fuel until the next time the pump is on. It is possible but how likely I don't know. That is what I think was going on with mine and why the car sometimes would run fine after shutting the key off for a few seconds and then restarting. It just took a little while for the crud to accumulate onto the strainer again. I think over time that is what killed my pump because it was likely starving for fuel a lot of the time. There is no switch or relay that shuts off in the event of a wreck for the Fieros. Just make darn sure you knock all the flaky rust/corrosion off the tank walls and if able and you have time, coat it with a sealer. If not, well you can only do what you can do... Your description of cleaning your tank sound a lot like how I did mine the first time. Any chance you can post a pic or two of the insides?

Charlie

I couldn't find my camera or I would have taken some pictures. I did look inside and it did have some rust, but it wasn't flaky at all. Just slightly bumpy surface rust so I don't think thats the problem. The debris theory is a bit of a stretch I admit, but maybe? I've got a Delphi pump in there now and drove it home without any problems.

I'm going to see about relocating the coil tomorrow. Hopefully that'll help too. I have an AC Delco ICM floating around somewhere too that may perform better than its off-brand brotheren as well, if I can find it that is.

The fuel pump will run 2 seconds for prime or two seconds past the last ignition pulse. If the key is turned on for a prime, then turned off and back on again within a short period it will not prime a second time. If you wait at least 1 min before turning the ey to on, it will prime again.