Intermittentish no run electrical problem (presumably)

[fx4m]

Hi Folks,

I have a 2003 Astro Van. I don't use it much at all, but I have a solar battery maintainer so the battery stays in good shape.

One day I went to use it and:
it cranked fine, but no hint of wanting to fire even a little bit
no fuel pump noise
gas gauge dead empty (not true)
lights on in the dash and elsewhere
I checked that fuel pump relay and the relay itself is ok, but the coil was only receiving 2 volts with the ignition on (measured immediately after switching on the ignition).

I had it towed to a shop and of course when it got there it started right up and ran fine.
I had them keep it there for a couple of weeks, trying to start it every day and it started every day. Except one time it suddenly died after starting and running for a few minutes and displayed similar electrical symptoms. But it started the next day.
The shop guessed that was an ignition switch problem, but they couldn't get it to fail again to test anything.
So I drove it home, went out every few days to start it up, which it always did. Then it suddenly died (no sputter) while warming up and hasn't started again. The gas gauge works this time, the fuel pump doesn't run at all. There have been no codes.

Any ideas?

[TBLBill]

Can you check voltage at the fuel pump? I would inspect the wiring to look for any breaks too.

[fx4m]

Correction: the gas gauge is shows dead empty (again) but the tank is full. I am going to try to disconnect and reconnect some connectors on the ECU to see if that might be the problem.

[fx4m]

Can you check voltage at the fuel pump? I would inspect the wiring to look for any breaks too.

I already know there is no voltage at the fuel pump because the fuel pump relay is not receiving enough voltage to switch on (and I observed it not switching on). And I know that the relay itself works. Also if I jumper around the fuel pump relay, the fuel pump runs fine, but the engine still doesn't start. Whatever is causing this is causing 2 Volts to to be applied to the fuel pump relay coil. (What is the normal voltage on the fuel pump relay coil when the ignition switch is on, but not running? I would expect it to be zero).

So, I see no reason to to try to remove the full fuel tank to measure the voltage at the fuel pump as the fuel pump and it's wiring seem to be working fine. I suspect the problem is with the ECU or it's associated wiring.

[gman]

Hi. Sorry to ask you a question in a thread that you're asking for help on, but can I ask how you tested the voltage of the various components?

Also, the wiring harnesses on the fuel pumps are known to melt, and that's why all replacements have a new "updated" design.
Another thing I've read about, is the injector wiring harness giving people some guff at times.
Could try tapping it while the van is running.

Though since your car is throwing a pump code, it could very well be that harness.

Again, i'm more interested in how you tested components (if you could give a process, as well as how you knew how much voltage each component was supposed to get, and where to test it, that would be great, thanks).

[markmitch]

I would suggest getting the wiring manual for the vehicle, then check all grounds first. a bad ground is the first thing to check and pretty simple to do just to eliminate that side of the problem.

[fx4m]

Hi. Sorry to ask you a question in a thread that you're asking for help on, but can I ask how you tested the voltage of the various components?

With a voltmeter, at the fuse box, during the first 30 seconds of turning on the ignition switch. I removed the relay and measured the coil voltage at the pins of the socket. The location of the relay and its pinout are easily found via Google. If the fuel pump relay does not engage, the fuel pump will not get any voltage. Since the fuel pump runs when I bypass the relay, it is safe to assume the fuel pump and its wiring are OK.

Also, the wiring harnesses on the fuel pumps are known to melt, and that's why all replacements have a new "updated" design.
Another thing I've read about, is the injector wiring harness giving people some guff at times.
Could try tapping it while the van is running.

The van does not run.

Though since your car is throwing a pump code, it could very well be that harness.

The vehicle is not throwing any codes.

[fx4m]

"Intermittentish" was probably too optimistic of a description. Failed, then ran, then failed, then ran, then failed over the course of a several weeks. It is currently not running for a couple of weeks.

I disconnected the ECU and the bulkhead connector (they were very clean) and put them back. The gas gauge then worked, for about a minute, but the van did not start.