My 96 Accord with 225K miles recently started randomly stalling while idling and driving. Sometimes after it stalls, it is difficult to restart. When it dies it just shuts off instead of slowly sputtered to a stall. I took to a shop and they thought it was bad ECU. I swapped out ECU but still have same issue. It starts up with no issue but either dies shortly afterwards or within a few minutes of driving. There are no CEL codes. I tried jiggling the key to see if it might be ignition switch, but that had no effect. Any ideas on what I should check next? Main relay, ignition control module?

 

An ignition switch (electric part) going bad? It's kind of common on the 90's Accords. I'll wait for someone to give you the testing procedure, but I think wiggling the key while it's running causes it to stall.
I only say that, as you mention it will start and run, but just stalls out. That means the main relay is doing it's thing, along with the entire distributor (ICM included). You could check fuel pressure, just to be sure you have what you're supposed to, and that the pump is working.

 

When I tried jiggling the key it didn't stall, so I was thinking the ignition switch might be okay.

Today I started it up and just let it idle in park for a while (at least 10 mins). Once it warmed up, it stalled out again, so now I'm thinking it may be temperature related. I also noticed the radiator fan never turned on unless I turned on the AC. After it died, I was able to start it up right away but then it stalls again within a minute. Any ideas how engine temperature may be impacting this?

 

The root of your problem can be numerous items, so any suggestion will be a guess.

Is your car an LX, DX, or EX accord? Trying to find out if your ignition coil is outside the distributor or inside.

Do you have a test light or spark tester? You need to determine if you have a spark or a fuel problem.

 

It is a DX automatic and no I don't have a test light or spark tester.

 

You might want to check your fuses for the ECU to make sure the old ECU didn't cause the ECU fuse to blow. There may be a fuse for the ECU in both the engine bay and interior fuse box.



You can use a screwdriver to test for spark on the plug wires. See video below for his spark test.

I'd recommend using insulated gloves just to avoid getting shocked when doing the test this way.

 

That's funny, I just finished watching that video right before I saw your reply. Since the car is starting and running for a while until it warms up, wouldn't that mean it is getting adequate spark and the ECU is working (at least until it decides to stall)? It almost seems like once it warms up, something is cutting the engine off abruptly.

 

As long as it's running, that means the spark is good and ECU is working. Then after a while, SOMETHING quits working.

The trick is catching it "in the act". You say it stalls, then you can immediately start it but then it stalls very quickly. Not sure how you can catch it, determine whether it's spark or fuel that cuts out...?

 

Agreed. That's why I suggested testing the fuel pressure, to make sure the pump is putting out what it's required. If I remember right, it's supposed to put out 46 psi at start up, then drop to 38 psi when running.If it's dropping more than that, it could cause it to stall. Then re-starting would cause the fuel pressure to rise up again, to allow it to run longer/again.
If you pull the vac hose to the brake booster, then shoot some starting fluid into the hose, it'll start. But if you keep shooting it, it should keep running as long as you keep shooting. Does this happen?

 

I'll see if I can rent/borrow a fuel pressure gauge from parts store. Do you know if the service port for this is standard or will I need some type of adapter to connect? If fuel pressure gets low when engine warms up, would that cause an abrupt stall or would it sputter out?