wont start

jmac

New member
1990 cherokee wont start change fuel filter will run on ether ,while filter was off check pump
 

There is a test valve on the fuel rail. Can you hear the pump run for a few seconds (prime) when you first turn the key to the run position? The pump should also run continuously as long as the engine is cranking. It won't run continiously with the key in the run position, it only runs for a few seconds to prime the fuel rail.
Before you tear into the pump there are a few things to check out first. Like the wiring harness and the starter relay.

You can take the yellow/black wire at the starter relay, usually marked "BAL" near the spade connector and touch it to power (big red wire at the starter relay) and it is a straight shot to the fuel pump through a few connectors.

Here is an old diagram I have.

FUELDIAG-1.png



I have an old freon gauge I use to test fuel pressure. The hookup on the fuel rail for pressure testing is the same as a freon hookup, the freon gauges seem to tolerate gas just fine.
 
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