"...the in-tank pump isn't working. how do I diagnose it...."

1) Reconnect the feed hose to the Main pump in case the Tank pump runs when 12V is "hot-wired" to it in Step 2.

2) Apply 12V to the Tank pump by removing fuse 5 and jumpering 12V to the RIGHT side contact and listen for the pump to run. Get the 12V from the LEFT side of any fuse 6 – 10.
[Fuse 5 is removed to isolate the Main pump from the applied 12V at this time.

How to "remove the hose on the far left that has black inner plastic/rubber sticking to the metal part of the in tank tip?"

Be careful taking the hoses off the sender pipes, which are probably very fragile by now.

For the Output (larger) hose, the clamp will probably have to be destroyed. I use a small, fine-toothed hacksaw to cut thru the clamp at an angle, then work the hose free by prying with a small screwdriver. The feed hose is usually long enough to trim some off, if mangled.

For the Return line (rubber sleeve over thermoplastic line) I saw the sleeve and line off at what I judge to be the end of the metal "barb" fitting.

To reinstall the Return line, I cut the outer sleeve back about 2" to expose that much of the plastic line, then "splice" it to the senser barb with a short piece of 5/16" ID Fuel hose (30 R6 is OK here) and two FI hose clamps. The return pressure is quite low, and this splicing method has worked for me several times with no problems.

When the sender is out, you may find the short internal feed hose on bad shape like the one below. If so, even a working pump can't put much out when the fuel level is low. The picture is one of many (MANY) in Art Benstein's detailed ''In the Tank'' photo essay, well worth reviewing before wrenching.




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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.