car runs for 2-3 minutes then dies.

[Ron]

...
Why didn't it fire off on either? My guess is the long convoluted intake path is not very conductive to the starter fluid atomization.

My guess is that it was probably flooded or fuel fowled. It is way more volatile than gasoline. And it's so "hot" that if you use too much (or on a hot engine, especially a diesel), you risk over revving or pre-ignition.
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So, you haven't tried it since this problem started?

Another option: When it dies, quickly pull a few of the easy to get at plug wires, connect some spare plugs, ground them, give it a spin and take a look. (Exhaustive go to ;-)

[FABombjoy]

My guess is the long convoluted intake path is not very conductive to the starter fluid atomization.

Not at all, it will start. Even if you have an air filter installed. You can spray starter fluid on the the air filter and it will still kick over. Very helpful for diagnosing a disconnected fuel pump relay.

[aharris82]

Update from today - Spark appears totally fine. Fuel suspect.


Hooked in my fuel pressure gauge rig between the distributor and the control pressure regulator. Tried to start, no fuel pressure, and wouldn't start even from cold. Took my pressure gauge rig off and set back up to normal, still won't start. Plugged in cold start valve just in case, no difference. re-unplugged cold start valve as DMCMW had done.

This time it didn't even run for the 2-3 minutes and then dying, it's just not starting.

Tried starting with starter fluid in the intake, and it happily sputters with it and tries to start! I think ignition/spark is good, after this and all prior tests.

My melted fuse slot #7 - I pulled up the fuse panel, and discovered it isn't attached to anything. Someone clearly wired a bypass of it at some point.

I do have the DMCH fuel pump & sender module, done by the previous owner in 2016ish.

I poured fresh gas into the tank today also, just to make sure this wasn't just bad gas.

So after I let it sit for a while, I started it up, and it ran it's 2-3 minutes again happily, then cut out.

After it died, I then tried jumping the RPM relay (slots 30&87), and nothing comes on. What does this tell me?

Also in case it's relevant, my car has a Stage II upgrade from DMCMW in 2020.


fuse 7 bypassed:
Capture.jpg

Fuel pressure rig:
Capture1.jpg

Fuel pump:
Capture2.jpg

[aharris82]

Then after a while, once cool, jumping the rpm relay (30-87) does turn on the fuel pump and frequency valve, as it should.

However after it runs its 2 minutes and dies, the fuel pump and frequency valve both stay off, even with rpm relay jumped.

What does this mean?

[Ron]

...
Hooked in my fuel pressure gauge rig between the distributor and the control pressure regulator. Tried to start, no fuel pressure, and wouldn't start even from cold.

First things first...
The valve should go between the WUR/CPR and FD. Double check all routing and rig the gauge like this:

GaugeSetup.jpg

[Bitsyncmaster]

Then after a while, once cool, jumping the rpm relay (30-87) does turn on the fuel pump and frequency valve, as it should.

However after it runs its 2 minutes and dies, the fuel pump and frequency valve both stay off, even with rpm relay jumped.

What does this mean?

Jumping the RPM relay connector pins 30 and 87 should only run the fuel pump. Jumping 30 and 87b should only run the lambda. You can make a jumper that connects them both to 30 (power) and do your testing with that. If the pump is not running, get a voltmeter and verify you have voltage on the jumper first. If so, your connections after the RPM relay or the pump is bad.

[aharris82]

So I jumped the RPM relay (30-87) and the inertia switch both, and it ran and stayed running. I attempted to get gas 5 minutes down the road, and then it wouldn't start after I got gas.

Waited 15-20 minutes, and then it started, so I got home but it was not running well the way home.

got home, put the inertia switch back and rpm relay back, and now it's running and stays running. It is returned completely to the state I had it before when it would run 2 minutes then die, but now it is running.....FOR NOW.

I just turned it off, and restarted just to check and it is acting fine.

So now my problem is apparently intermittent. GRRRRRRRRRR

[Ron]

You removed the RPM Relay and jumped 30 to 87, but not 30 to 87b, and it kept running??

[Helirich]

One thing I would look at is the stand alone fuse (#7). You show the pic of it missing, but not the new fuse. On mine, the previous owner had installed a smaller wire inline fuse holder that would get hot and not let 12 volts to the pump. When you speak of the numbers on the relay, is it the brown wire you are connecting to the purple/white? That never fails to run my pump. (I have that same pump) Your jumper wire should be 12 ga so as not to reduce voltage to the pump.

[aharris82]

You removed the RPM Relay and jumped 30 to 87, but not 30 to 87b, and it kept running??

Yes, and I assume thats why it didn't sound excellent, a little jumbly and minor backfiring. Since that would keep the lambda offline?