I have a 1986 ford f150 302, just changed battery and unintentionally
cross neg and positive for split second. The truck didn't have any
power at all, no dome light, radio, ignition. I changed the starter
solenoid, still nothing. I found a wire burnt in half next to the
solenoid, I corrected this and the lights immediately came on. Now
when I start it it fires up for 2 seconds and immediately shuts off, I
came hold the gas but still turns off immediately after it fires. I
think possibly a relay is bad but not sure where to start. Any help
will be greatly appreciated.
On Mon, 8 Jun 2009 20:21:31 -0700 (PDT),
You have probably burned the fusible links. These are fuses
in effect which look like wires including the one near the
solenoid that you replaced. They have specific electrical
qualities to function as a fuse. They must be replaced with
like links of the same length to function as intended.
Regular wire will not replace a fusible link. You truck has
several of these all of which are required. When you are
using the starter, the ignition is supplied thru the start
circuit. When the switch is released to run, the ignition
is supplied thru the run circuit. There are fusible links
for the run circuit and the ECM as well as the fuel pump
IIRC on that one. I do not recall the exact location of the
fusible links. I believe they were all yellow in the
harness on or near the left fender. Make sure you replace
them with the correct links. You need to get hands on a
vacuum and wiring manual for it which will give you all the
info needed to quickly locate and test the circuits. It is
probably still available from Helm, inc or can probably be
found somewhere on ebay.
A quick check of the wiring diagrams shows that there may be as many as
(depending on equipment) nine fusible links attached to the starter
relay hot terminal.
You can't solely rely on a visual inspection, you need to pull on the
fuse link to see if the outer jacket stretches, if it does, the wire
inside has opened.
Also, since you've already swapped out the starter relay, make sure you
didn't leave any fuse links disconnected or connected to the starter
side of the relay versus the hot side. i.e., they should all connect to
the relay post that the battery cable connects to.
I am not sure if that year still had one but this sounds suspiciously like
an open ballast resistor. Passes current with the key in start posn but when
the key is moved to the run posn there is no juice to the coil.....
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