My '98 4x4 Blazer quit while 100 miles from home. Went from doing 70mph on the interstate to dead alongside the road.
Crank but no firing at all. No mechanical noises, coolant in the oil or any other "serious" problem, but I couldn't hear any fuel pump noise when operating the ignition, and the fuel gauge registers way above full.
I'm thinking that because the fuel level sensor and the fuel pump are in the same unit, they would share the same wiring harness/connector?...so both going would point to a connector, wire or ground problem?
Is that a reasonable guess?
Thanks.

 

It's easy enough to verify with a proper fuel pressure test.

George

 

I cycled the pump, and depressed the test port schrader and got no fuel at all. When I say "cycled the pump", that's to say I turned the ignition "on" and left it there while depressing the valve. If the pump was working, wouldn't I get a spray of fuel?

 

If there is no pressure at the shrader after key on then yes you have a problem. You can start by checking the ECM B fuse 20A In the UHBEC. If thats good then you can check for power and ground at the fuel pump connector before condeming the pump If your working alone you may have to hot wire the pump.

George

 

If it has a fuel pump prime terminal in the fuse box, try applying 12V+ to that. If it runs that way, you can focus on the fuse and relay.

Also, try kicking the bottom of the fuel tank (or hitting it with a rubber mallet if you can't reach under). I've started many "dead" fuel pumps that way (though not usually when they quit going down the road). It's far from a permanent fix, but it's always easier to drive them into the shop than it is to push them.

 

The wiring diagram does not show a priming terminal but Tom's suggestion reminded me that I should have suggested swapping the fuel pump relay with a known good one and to use the relay sockets to hotwire the pump before climbing under to check at the pump connector.

George

 

Thanks for the suggestions.
Another clue...my scanner won't connect. I've used it many times before with no problem.
The battery is new and charged. Cables are tight. OBD connector is good. Fuses are ok.
Any ideas?
Where should I start?

 

Check power and ground at the ODBI socket.


George

 

Well...doing what I should have done on the side of the road, I pulled and checked every fuse, not just those associated with the fuel pump, and #10 was blown. Replaced it, and the fuel pump, gauge and OBD port work, and it starts now.
But...why did it blow that fuse?

 

Which fuse is #10?

George