I have lost power to the in tank pump at the fuse panel. While I'am looking for the problem and or another wiring harness. I made a fused jumper wire from the backup lights extra terminal on the fuse panel to the extra terminal on the in tank fuse. Now the 245 runs fine. But have I created a ticking time bomb?

1987 245. The engine harness is coming apart. I think that is where the power loss problem is. I have cleaned and change the fuses to the glass stainless type, but it didn't change anything. The fuse panel itself could be a problem. The heater blower shows signs of heat ie. burned color. The blower does work though. When the car quit running there was a faint electrical smell at the panel.

Andrew,

Please be more specific about "...the power loss problem...".

What is the car doing — or not doing?
What have you looked at, relevant to the problem?
Are you testing for power with a meter or test light?
What led you to suspect/test the tank pump fuse?

I know the engine harness insulation goes bad, but power from the Fuel Injection relay to fuse 4 is entirely inside the car, and is seldom a problem. (Although the fuse panel area could be, if water has leaked in.) I'm guessing you have some kind of fuel issue, but my guessing doesn't help much.

If you have a meter or test light, I may be able to offer some tips to isolate a fuel problem — or suggest other things, such as the 25 amp fuse near the coil.
--
Bruce Young,
'93 940-NA (current), '80 GLE V8 (Sold), '86 240dl, '85 244 ti, '83 245t
'76 244 (R.I.P at 255k), 73 142 (98K), '71 144 (ex circle track car)
Used '70 144 from '78 to '92, New 144 from '67 to '78, Used '62 122 from '63 to '67

May be OK if your jumper goes to one of the tank pump fuse output terminals (either of the top 2 push-ons), and you don't have a fuse in the holder.

With a fuse in place, the jumpered voltage could feed back to the Main Pump also. Not necessarily bad (as a diagnostic), but maybe not what you intend.

How about some details on your car year, and what led you to determine that you have a "failing wiring harness"? In my experience, the fuse wiring is not prone to the same failures as the underhood harness.
--
Bruce Young,
'93 940-NA (current), '80 GLE V8 (Sold), '86 240dl, '85 244 ti, '83 245t
'76 244 (R.I.P at 255k), 73 142 (98K), '71 144 (ex circle track car)
Used '70 144 from '78 to '92, New 144 from '67 to '78, Used '62 122 from '63 to '67

what year is the car? what i'd do is pull the trim and then pull the wiring off the fusebox-1 fuse at a time. each female end, pinch slightly to tighten the connection. then pinch the fuse clips together and replace the fuses with copper or brass-no aluminum. good luck, chuck.

I had the same problem with my 81 242 and i did much the same solution. of couse i don't wnt to legally responsible BUT what you have done should be fine assuming that the fuse for the lights can handle the load. one way to make sure that the intank pump dosen't get much of a load is to not run the tank all the way down. For my 242 I typically would go about 200 miles and refill the tank. Hope this helps!