Testing fuel pumps on TBI, but different

[D.FENS]

Just about reached the end of the interweb on this one. If the info is out there Google can't find it and neither can I. Both Haynes and Chilton CD-ROM manuals are super vague about the subject. Do not have a dealer service manual on my truck, if anybody has one I would be interested.

I'm thinking one or both of the fuel pumps on my '88 crewcab have played out. 7.4L TBI, dual tanks. Pumps are SUPPOSED to be in the tanks, I guess they are because I can't find a main pump underneath the truck. Just a giant oil-filter looking deal rigged up in place of the factory fuel filter.

Google searching tells me there is (again) SUPPOSED to be a fuel pump test circuit on the ALDL plug under the dash. My truck does not have a pin in position G like the interweb says it's supposed to. I'm guessing that may not be used for dual-tank and / or big block trucks, don't know.

So, with the common test method not available here, is there an easy way to test both pumps independently?

There is a red / white wire, with a grey connector, plugged into the fuse box adjacent to the ECU power wire. Is that the one I'm looking for? I did find a couple of forum posts suggesting you can test a dual tank truck out under the hood but did not say where.