93 GT hot starting problem
07-09-2008, 08:57 PM
#1
Thread Starter
Join Date: Jul 2008
Posts: 2
93 GT hot starting problem
I'm new to this forum, but was hoping someone might be willing to help with this issue, even though it has probably already been addressed before. I could not find exactly the same symptoms on other posts, so..... here it is!
1993 Mustang GT 5.0, Automatic
Starts fine when "cold," runs at a higher rpm until warm, then idles well. Once car warms up, if you turn off the ignition and try to restart, it will turn over but not actually start. Starter does not seem to drag at all, just cranks over and over.
Used a simple spark tester to see a spark on coil wire and on a couple of plug wires, definitely saw spark. I can't say it was bright blue, more red/ orange, but it was there.
Hooked up fuel pressure gauge to fuel rail and saw pretty steady 30 psi.
Replaced fuel pump, fuel filter, TFI module, distributor (including cap and rotor), ignition coil, plugs and plug wires, TPS, and still does the same thing. I checked the vacuum line on the fuel pressure regulator and did not see any gas coming out, so I assume it is ok (especially given the steady pressure on the fuel rail). Put a 12v LED across the fuel injector plug, saw slow "weak" pulse when cranking and low idling and much faster "strong" pulse when revving the engine (that makes sense, and seems ok to me).
That being said, we do know how to get it to start in this condition; use the fuel cutoff "inertia" switch. Pull up the red button which cuts power to the fuel pump, then crank the engine for about 4 seconds and it will actually catch and start. Immediately push the red button (to turn on the fuel pump) and it starts on up and runs just fine.
Because of that, I am thinking it must be flooding?! What can cause flooding on the EFI? Could the injectors all be allowing fuel to seep through, so that once fuel pump is on it quickly floods? I did not try turning on the ignition for a minute or two (so fuel pressure would build) and then try starting. I guess if that prevented a start it would point to flooding whereas if it started fine that would mean it is definitely heat-related, right?
What does the Engine Coolant Temperature sensor do, exactly? I assume it provides signal for the temperature gauge in the car (which seems to function) but does it have anything to do with fuel? Is it even worth trying the ECT?
Any suggestions would be greatly appreciated, as the next step is replacing the ECM, if I can find a replacement!
1993 Mustang GT 5.0, Automatic
Starts fine when "cold," runs at a higher rpm until warm, then idles well. Once car warms up, if you turn off the ignition and try to restart, it will turn over but not actually start. Starter does not seem to drag at all, just cranks over and over.
Used a simple spark tester to see a spark on coil wire and on a couple of plug wires, definitely saw spark. I can't say it was bright blue, more red/ orange, but it was there.
Hooked up fuel pressure gauge to fuel rail and saw pretty steady 30 psi.
Replaced fuel pump, fuel filter, TFI module, distributor (including cap and rotor), ignition coil, plugs and plug wires, TPS, and still does the same thing. I checked the vacuum line on the fuel pressure regulator and did not see any gas coming out, so I assume it is ok (especially given the steady pressure on the fuel rail). Put a 12v LED across the fuel injector plug, saw slow "weak" pulse when cranking and low idling and much faster "strong" pulse when revving the engine (that makes sense, and seems ok to me).
That being said, we do know how to get it to start in this condition; use the fuel cutoff "inertia" switch. Pull up the red button which cuts power to the fuel pump, then crank the engine for about 4 seconds and it will actually catch and start. Immediately push the red button (to turn on the fuel pump) and it starts on up and runs just fine.
Because of that, I am thinking it must be flooding?! What can cause flooding on the EFI? Could the injectors all be allowing fuel to seep through, so that once fuel pump is on it quickly floods? I did not try turning on the ignition for a minute or two (so fuel pressure would build) and then try starting. I guess if that prevented a start it would point to flooding whereas if it started fine that would mean it is definitely heat-related, right?
What does the Engine Coolant Temperature sensor do, exactly? I assume it provides signal for the temperature gauge in the car (which seems to function) but does it have anything to do with fuel? Is it even worth trying the ECT?
Any suggestions would be greatly appreciated, as the next step is replacing the ECM, if I can find a replacement!
07-09-2008, 09:18 PM
#2
D.R. THE PATHETIC DORK
Join Date: Jun 2007
Location: West Virginia
Posts: 30,863
RE: 93 GT hot starting problem
ect provides an input to ecm and is one of the sensors that plays a small part in fuel calculations......but first things first........I'd run a koer test and check for codes and after that check for bleed down of the fuel system by watching pressure gauge at rest
07-10-2008, 03:20 PM
#3
Thread Starter
Join Date: Jul 2008
Posts: 2
RE: 93 GT hot starting problem
Thank you. I am going to have to get my dad and brother (brother's car, actually!) to help with this, since I'm traveling. I didn't realize you could use the "Check Engine" light to read codes, we were waiting for another guy to bring a code reader, but he never did. I'll see if I can convince them to take the time to try this before I get back in town.
Thanks again, and I'll let you know what we get!
Thanks again, and I'll let you know what we get!
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