Join Date: Dec 2006
Location: Northwest Indiana
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Re: electrical draw in 89 F-250 7.3L IDI
Does the '89 still have the separate voltage regulator on the inner fenderwell on the passenger side? If so, I would change this, it's a cheap item.
Otherwise, the best way I know to locate small amp draws is to disconnect both positive battery cables, and hook up a digital multimeter between the positive battery terminal and the positive battery cable. Be sure your ignition is off when you do this, you definitely don't want to try to feed your glowplugs through your meter, it will burn the meter up for sure. Set the meter to DC amps, and it should show some current flowing. You then start pulling fuses out of the fuse box, one at a time, and observe your meter to see if the draw has reduced or gone away. If all of your fuses are out and you still have draw, then start disconnecting things like the wire going to the alternator, the wires to the 3 different solenoids on the injection pump, etc etc. You are using the disconnections to isolate which system/circuit the draw is in. Once you find which system the draw is in, it'll give you a narrower place to start looking.
1986 F250 2WD Super Cab XLT Lariat w/ 1996 front clip. Dually bed & van rearend (2" wider, allows spring clearance). 6.9 w/ approx 120,000mi. Banks non-wastegated turbo system, Wellman G088 glowplugs, Delphi BB injectors, Kenworth pyrometer, vac/boost gauge, electric water temp/oil psi/voltmeter mounted in dash. 3" Mandrel-bent open exhaust. C6 trans, 3.54 gears. Okiegringo idler pulley. R134a A/C conversion. WMO/diesel blend in one tank.