Determining pump operation over the internet is hit or miss using someone's hearing or feeling. You can improve this a bit under the hood.

Connect the 4-6 jumper as before, but take heed, the '91 uses fuse 6 to protect the wiring to the fuel injection system and the main pump, and fuse 4 for the oxygen sensor heater and tank pump. Make sure your jumper is getting its source from the battery side of fuse 6 (the left side) and fuse 6 is indeed delivering power to the load side by checking power there. The usual problem is a poor connection at the fuse end.



Then, with power verified on the right side terminal of fuse 6, you can go under the hood and give the return hose a squeeze, using your sense of feel, to determine the fuel pressure is enough to regulate.



Then, with the key on, verify the system relay is sending power to the fuel injection system:


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Art Benstein near Baltimore