STRANGE fuel pump/rear window problem, out of ideas

[dyeager535]

Unfortunately my '91 wiring diagram is near worthless for things like this, unless you spend two days trying to decipher it. You just need to know now what that ECM B fuse feeds. It may already be in another post if you search.

Odd that the fuel pump doesn't run when you bypass the relay. Don't believe the fuse has any play there.

 

[bowtieboy42]

I found this in a different thread, seems to be what I need. I'm just not sure how to actually diagnose the components (looks like just the fuel pump relay and oil pressure sending unit?)


Also I have those aftermarket oil/electric/temp gauges. Is the oil pressure switch in the diagram the one that feeds the gauge (in the head?), or is there an additional one somewhere else.

 

[dyeager535]

For a gauge, they use a sender. A switch is just that...on/off. That switch allows the fuel pump to run if the fuel pump relay fails.

The pressure sender is normally on the drivers side next to the distributor. Bell-shaped piece.

 

[bowtieboy42]

For those curious, I did eventually figure out the ecm-b fuse blowing.

One of the first things I did was buy a new fuel pump relay. Luckily I left the old one on the firewall as well (no AC relay).

Anyway, after tracing wires and finding no breaks, I eventually said, 'why not put the old relay back in?'

Sure enough, good as new. 202,000 and going strong. The brand new out of box relay from advanced auto must have been bad. Another quality made in china part.

I can't thank everyone enough for there help. Its people like yourselves that have allowed me to learn as much about cars as I know now, and help me learn more every day. I look forward to being around coloradok5!