BillHolden

After a half hour road trip when I come to a stop the engine just stops while in drive. Then it will crank but won't fire. I traded 2 of the relays around and it started. This happened several times. Yesterday I bought 2 new bosch relays and replaced them. It died again when I stopped on the way home.
It always starts after playing with the relays.
I am thinking it is the fuel pump overheating. Any ideas or experiences like this?

RangoWA

Muffler bearings! Seriously though I just went through that with my Hyundai. Not a fun thing and good luck not getting plowed into if you're in the road. In my case after tearing half the car apart it turned out to be the pcm relay.

It was one of the first things I checked but it was intermittent. It, like some (most?) relays has a diode in it and diodes can start acting squirrely. A part the size of an ant took me out and cost me a months work. I know better now though. Learned a LOT.

You can jumper the connection the relay performs to the pcm fuses with a heavy gauge wire temporarily. I'd pop it out if I stopped the engine since engine electrics would still be energized.

Cheap fix if that's your problem.

BillHolden

It is the ECC relay that I trade for the horn relay. So I am thinking all I have been doing is resetting the ecc. The horn still works, so the relay is not the problem. The check engine light is not coming on so.... (I don't have a code reader anyway)
So something is sending a message to the ECC to shut down engine after long drive.

BillHolden

The muffler bearings are fine. I replaced them last year!!!!

I put in a brand new relay for horn and ECC. The diode for the PCM is separate from the relay. I will research this. Thanks!

RangoWA

I forgot that about the Ford, saw that when I decided to bone up on the parts and locations just in case. I believe it's next to the A/C relay. Maybe it can be reversed (it's pointing the opposite direction) and swapped?

BillHolden

RangoWa
You said"Maybe it can be reversed (it's pointing the opposite direction) and swapped?" What do you mean?

RangoWA

The diode holders have arrows on them (depictions of the symbol) which is the direction of current flow. On mine the two are pointing in opposite directions, being next to each other, towards or away from each other, I don't recall off hand. But I imagine they could be swapped, just be careful to keep the orientation the same.

The way I understand the diode in a relay is to instantly shut down the magnetic field of the coil. Without the diode the field can continue momentarily and sensitive equipment doesn't like that. So the diode kills the field right when you kill the engine. A flaky diode can shut down the electromagnet any time, which opens your contacts, to the pcm in this case, which shuts down the pcm, which shuts down the fuel pump, ignition system and everything else the computer controls. When mine went out I had no CEL lit up on the dash, so I know what to look for now. I assume the Ford is similar.

Jbrew

I can tell you for sure they do that when the trans is low on fluid.

BillHolden

Tranny is up

BillHolden

It only died once since I put bosch relays in so i think we got it. I was told that the computer takes time to recognize new parts. Here's hoping. Thanks for all the help!