I was driving to work the other morning. I got 3/4 mile away, went over a small bump (after going over two large bumps... railroad tracks) and the engine immediately died. As far as I can tell, I have spark and the fuel pump is working. The injector seems not to be firing. I'm going to go rent a noid light set, but what could I have done? Is this car ever going to stop breaking my heart?
Using a 30 year old car as a daily driver is unusual and will always lead to surprises. In this case it may be as simple as a loose connector at the ICM.
I disagree with the premise that a 30-year-old car cannot be a good daily driver.
However, you have to go over the entire car and bring everything up to good condition.
Taking the approach of fixing things as they break, well of course you will be disappointed, because after you fix the current weakest link, the next item isn't far behind.
I disagree with the premise that a 30-year-old car cannot be a good daily driver.
However, you have to go over the entire car and bring everything up to good condition.
Taking the approach of fixing things as they break, well of course you will be disappointed, because after you fix the current weakest link, the next item isn't far behind.
That is also a slippery slope because many times "fixing" what is not necessarily broke can lead to doing a whole lot of work and never actually driving the car. Many of us fall to this and we miss the biggest point in owning a Fiero, just driving the thing!
So far, out of the ~30 times I've driven the car, It's broken down 3. It won't pass emissions because the valves don't seal. Now it doesn't run at all!
So what causes the injector to fire? Obviously ECU, anybody have a wiring diagram of that system?
to trouble-shoot. Crank the starter and watch the tach. if it goes up to 300 or so, the primary ignition is working. If it does not move, test the ICM, pickup coil, or ignition coil. If it does move, get some starting fluid and see if the engine responds to that. If it does, the car is not getting fuel. Listen for the fuel pump when you turn the key on. It should run for 3 seconds or so.
give us a report and we will go from there.
[This message has been edited by Gall757 (edited 02-10-2019).]
My tach doesn't work, so that's shot (although I did pick up a cluster from a pick and pull yard). I have one of those light up spark testers, so I know i have spark. I verified that I have fuel (but I don't have the required adapter to actually check pressure) coming out of the pump. There isn't a drop of fuel spraying though. I rented a noid tester at oreillys, so I'll give it a whirl tomorrow.
As far as I can tell, I have spark and the fuel pump is working. The injector seems not to be firing.
Because none of us know your mechanical abilities, I'd be curious how you arrived at those conclusions. It would be a wasted effort to describe how to troubleshoot an injector for example if in fact you have no fuel pressure.
[EDIT] Your last post appeared while I was typing.
quote
Originally posted by arbakken:
I verified that I have fuel (but I don't have the required adapter to actually check pressure) coming out of the pump. There isn't a drop of fuel spraying though.
Did you check before or after the fuel filter?
[This message has been edited by Patrick (edited 02-10-2019).]
My mechanical ability is very high. I have a 2 year auto mechanics degree, a 4 year mechanical engineering degree, and have thus far not paid anyone to fix any part of my car that wasn't alignment or a/c related.
It was pre fuel filter, but I highly doubt hitting a bump caused my brand new fuel filter with ~20 gallons through it to plug solid.
On a somewhat related note, does anyone know of an adapter I can install post fuel filter that I can permanently mount a small fuel pressure gauge to?
My mechanical ability is very high. I have a 2 year auto mechanics degree, a 4 year mechanical engineering degree, and have thus far not paid anyone to fix any part of my car that wasn't alignment or a/c related.
Just so you know, it's been the ASE certified mechanics posting here over the years who've often seemed to have the most problems with their Fieros. Seriously!
quote
Originally posted by arbakken:
On a somewhat related note, does anyone know of an adapter I can install post fuel filter that I can permanently mount a small fuel pressure gauge to?
A simple brass T fitting will do the job... as I used on my Subaru.
I disagree with the premise that a 30-year-old car cannot be a good daily driver.
However, you have to go over the entire car and bring everything up to good condition.
Taking the approach of fixing things as they break, well of course you will be disappointed, because after you fix the current weakest link, the next item isn't far behind.
^ lol, fair enough! I am still planning on the ability to DD the thing. I bought this one because it seemed the PO had done a lot of work on it (paint, new engine) so I wouldn't have to... it's always a gamble anyways. I am planning on making it dead reliable and nice to drive, but the head wasn't done at the same time as the engine, and I get a LOT of cylinder leakage out the valves. I was going to fix the head once it was motorcycle weather, but I'm not fixing the tach or suspension until I get it to pass emissions.
Anyways, I did a noid test, and the injector is NOT getting the signal to fire. Again, I do have spark. I can't find a wiring diagram that shows anything about the injector wiring. Does it go straight through to the ECU?
Found a diagram. So basically the red wire should be hot all the time, and the blue is grounded by something... wiring diagram says it's ignition control inside the ECM
Fuel gauge is a bad idea for full time use. Any gauge might seem to work but they often leak and leaking fuel causes fires or worse.
test adapters See my Cave, TBI Test Adaptor then use search here to find updated part #. Can find bigger one but new valve won't fit all gauge sets. Small one work w/ the filter but need to release support(s) that holds metal lines to get clearance.
Note that gauge sets that reads 75-150 PSI are often inaccurate at ~ 10 psi duke uses. I would just switch high reading gauge to read 20 - 30 PSI max.
But...
This problem can be a lot of problems... Example: ECM can't see HEI for any reason then ECM Will Not turn on the fuel injection. That can be Iffy HEI, iffy ECM and/or any wiring in the car. See my Cave, HE Ignition and Wire Service I would check/clean/fix all grounds at minimum and fix whatever for this too. Just 1 iffy ground can cause a lot of headaches.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
Fuel gauge is a bad idea for full time use. Any gauge might seem to work but they often leak and leaking fuel causes fires or worse.
test adapters See my Cave, TBI Test Adaptor then use search here to find updated part #. Can find bigger one but new valve won't fit all gauge sets. Small one work w/ the filter but need to release support(s) that holds metal lines to get clearance.
But...
This problem can be a lot of problems... Example: ECM can't see HEI for any reason then ECM Will Not turn on the fuel injection. That can be Iffy HEI, iffy ECM and/or any wiring in the car. See my Cave, HE Ignition and Wire Service I would check/clean/fix all grounds at minimum and fix whatever for this too. Just 1 iffy ground can cause a lot of headaches.
That adapter says 87-88, will it work with my 85?
Uhhggg. I was assuming since the ignition was working the ECU knew what was going on, that seems to not be the case. Well, that gives me a lot to go on. A junkyard L61 Ecotec swap is seeming more imminent! lol
So, after a little more diagnosis, I am getting signal from the distributor. I am, however, not getting power from the Fuseable Link F. How can I tell which one is F? At what point does that wire turn from a red fuseable link to two orange wires?
Cool! I don't remember seeing those back there, but I might have just missed them.
Another question, on both ECU plugs, the highest number pin (22 and 24) has a white wire going to them. On one of them, it pulled out of the connector. It doesn't appear to have a wire in it, it looks like a hose. What is that? What does it do?
So, after a little more diagnosis, I am getting signal from the distributor. I am, however, not getting power from the Fuseable Link F. How can I tell which one is F? At what point does that wire turn from a red fuseable link to two orange wires?
Back up a bit. You should have fuses labeled INJ1 and INJ2. Since you only have one injector, you only have to worry about one fuse. Check those. (Probably INJ1.) The way the Fiero ECM works, is that 12V is supplied to the injector at all times. The ECM switches ground, in order to fire the injector.
Here's the rub... If the ECM is not seeing ignition pulses from the distributor, it will not fire the injector. Of course, that's hard to diagnose, since your tach isn't working. But since you have already determined that you have a signal from the distributor, we'll assume that's good.
Back up a bit. You should have fuses labeled INJ1 and INJ2. Since you only have one injector, you only have to worry about one fuse. Check those. (Probably INJ1.) The way the Fiero ECM works, is that 12V is supplied to the injector at all times. The ECM switches ground, in order to fire the injector.
Here's the rub... If the ECM is not seeing ignition pulses from the distributor, it will not fire the injector. Of course, that's hard to diagnose, since your tach isn't working. But since you have already determined that you have a signal from the distributor, we'll assume that's good.
Yeah, so the 10A fuse (1) from the panel is good, checked that first. The ecu should have hot all times 12v from the two orange wires (fusible link F) and doesn't. I was doing a bit more internet research yesterday, and found this which is absolutely my problem. It snowed again and so my fusible links are buried in snow at the moment, going to let it melt a bit so I can see what's down there. Why couldn't it break down in the garage?
Seriously!
