My Iron Duke has recently developed a problem where it will not start, but will idle once I can get it started.
When I turn the key to the Start position, a small spray of fuel comes out, but the engine will not start. When I return the key to the "On" position, some fuel drops into the bowl. If I do this 2-3 times, there is enough fuel in the bowl to briefly start, then it dies.
If I remove the injector, about a teaspoon of fuel drops into the bowl.
If I attempt to start again after replacing the injector and putting everything else back together, the engine will start after 1-3 attempts. Due to being flooded, the engine has rough idle for between 30-45 seconds and then settles in to an idle between 800-1100 rpm. Average is around 900 rpm.
When idling, the spray pattern from the injector is what you would expect - consistent spray in a fan pattern. I can rev the engine and it will return to idle without dying.
Thus far, I have: - Replaced the fuel injector - Replaced the fuel filter - Replaced the fuel pressure regulator diaphragm - Replaced the PCV valve (I realize that this should not have anything to do with the problem, but the old one, while functional, was nasty)
When you turn your key to ON (not START), do you hear the fuel pump prime for two seconds? And does fuel not exit the injector at this point? (It shouldn't.)
[This message has been edited by Patrick (edited 08-20-2022).]
My first Fiero 25 years ago was an '87 duke. I never liked that engine, and the '88 duke is very similar. Hopefully The Ogre sees this thread and responds. He's quite familiar with these engines.
I suspect something has failed that's supposed to act as a "choke" when you are cold starting your engine. Could be the MAT (Manifold Air Temperature) and/or the CTS (Coolant Temperature Sensor). If either sensor is reading too high, your engine won't be supplied a rich enough mixture to cold start.
[This message has been edited by Patrick (edited 08-20-2022).]
skip other testing, worse replacing parts, until test fuel pressure.
Need a gauge set AND TBI Test Adapter. see https://www.fiero.nl/forum/Forum2/HTML/146121.html allowed is 9-13 PSI... BUT... If low, even above low allow = 9psi, then very likely fuel pump or soft hose attach to output to steel line is "bad."
Problem seems that even if both are "good," GM used plastic clamps on the rubber and fails to seal 30 years later. I don't think the clamp are bad but "rubber" get softer and clamps just hold hold.
------------------ 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)
Thank you Ogre and Patrick. I will check the fuel pressure but I will be shocked if it is too low. As part of the restoration process between Oct-Dec last year, I replaced the fuel sending unit. I installed a fuel pump for a Buick Grand National in the unit.
Install a new/used pump but did you use J30R10 hose? If not then gas can eat other types and leak @ minimum. If you reused factory hose, was weak to start and likely failed.
⚠️ Putting high pressure pump in duke's tank often causes problems because high pressure and volume can "peg" the TBI regulator full open and still have too much PSI for injector etc to deal with. If you reused old duke hose for pump joint likely will fail w/ high pressure pump.
ECM may have problems anyway from heat and other issues. Example: ECM must see ignition before running the injector... problem is ECM may see that and turn on injector but injector driver circuit have problem and injector get intermittent or no ground to run. Need a Noid light to check that ECM tries running the injector when won't start. Often You won't get a "code" and see nothing using a scan tool for iffy ECM. If sensor(s) or battery volts are unstable w/ key on, engine not started then maybe iffy ECM or power ground or both to it have problems.
Thanks again! Fuel pressure is definitely not the problem. Noid light connected to injector power resulted in a dim, intermittent glow during start - and it will not start. Checked ECM and TBI fuses and both are good.
ECM can seem to work yet have crack solder joints and other problems and just one output doesn't work. Worse because of heat and little air flow. See my Cave, ECM Heat
On top many old GM ECM has Factory Defect w/ "sealing paint" that cause problems too that can lift surface mount parts etc and "kill" the ECM.
Years ago had 87 duke ran one day, cool off overnight, and won't start next day until replacing ECM. I had extra but old unit out of GrndAm so worked for some years... But... Now I'm waiting on Reman Cardone ECM right now because of "dead" ECM as one problem is while computer "ordering" the Radiator Fan On, does not ground the wire to turn on the fan. I save old sensors to test this and ECM Scanner "Sees" coolant hot and fan 1 On but isn't. And jump ECM plug to ground for this will turn on so isn't a wiring problem.
If need one... AZ has Cardone ECM and currently big discount from AZ web ship to home. Return the core to any local AZ store to save money shipping a core. Save the PROM to install in the new ECM.
Thank you very much! I ordered a Cardone ECM from AZ. It arrived today. I transferred the PROM from the old to the new ECM.
I disconnected the positive battery cable, installed the ECM, and then hooked the power back up. It cranked, started, and idled just fine. Did two more starts just to feel comfortable that there is consistent performance.
Oh, and I used a Sharpie to record on the ECM's case when I replaced it, along with the Service #, PROM External ID, PROM internal ID, and that the PROM is original to the vehicle. That's all thanks to your PROM ID without a scanner page, Ogre.
Now to put everything back together, then test drive to fill up and return the old core to AZ.
Take a pic of old ECM and make sure you can read the label in the pic. Shapie and other "permanent" marking in metal and plastic can fade or otherwise not readable months to years later.
