deadmeat

Just a bit of a heads up on this rats-nest of a truck: This 1992 F150 Custom began life with a 4.9L and a E40D. Someone hastily hacked up a (supposed, I'm still trying to find proof of it) Mustang, year unknown, and swapped in a 302 with some "rebuilt" C6. They spliced into the original electronic ignition and put a Edelbrock 1406 carb on it. I know it was a stupid idea to get it, but that's beside the point. My poor '92 Escort succumbed terrible blow-by and picked up a nasty smoking habit. From what I can tell a lot of the electronics and safety systems were disabled to get it working.

The main problem now it refusing to start. I hopped in it and flipped the key to the Start position: no cranking. I noticed at this point the voltage (on an always-on secondary meter) plummeted to 0V and stuck there for a minute. It slowly rose up and returned to 12.5V. At the same time, pressing the brake in made it fall to 0V again. After letting off the petal returned immediately to 12.5V. I fiddled with the solenoid and bench tested it with a secondary 12V source. It actuated with no problems. After putting it back on I noticed the ignition wire going to the solenoid was carrying current with the key on the off position. After reconnecting the battery the truck began cranking constantly. I'm not sure what demons I awoke in this truck, but I'm at a loss for what's going on.

Another few notes: The radio now has a mind of it's own. The power seems to come and go and the unit turns on randomly without much regard to my input with the key. The stereo sometimes does a "first time power on" start, as if the constant 12V lead loses power. Also, the headlights seem to not work or come on anymore. I've done a bit of poking around and I would guess the ignition module died? But I also question the ignition cylinder.

Any and all help would be greatly appreciated. The poor girl is stuck in a Burger King lot and luckily the manager seems to be sympathetic and is letting me keep it there until I get it figured out. But I don't want to push my luck.

BareBonesXL

Much of what you wrote doesn't really fit together. The voltmeter dropping to zero might be because of the way the meter is connected. Most systems cut power to accessories during Starting. You can't measure current if the battery is disconnected, so not sure what you meant when you said the solenoid wire was "carrying current". The fact that you took the starter out, and the constant cranking problem started after you reinstalled it, suggests that you misplaced some wires on the starter or starter relay. The voltmeter dropping to zero when you press the brake pedal suggests a loose wire. Crawl under the dash and see if anything's getting pinched.

Don't have much to offer except to say that you need to work on your electrical system understanding and troubleshooting. No offense. Guessing that ignition module died, without checking for power at the coil or the module is one sign. There are some fundamental steps to take for problem-solving. Study up and take some more measurements.

deadmeat

What?

BareBonesXL

Sorry, most people call that the starter relay. Got it confused with the starter, where many manufacturers put the combined solenoid/relay/bendix mechanism.

https://www.rockauto.com/en/catalog/...ter+relay,3804

Same concept applies. You took it off, then something was different when you put it back on. You probably mixed up some wires.

Steve83

You need to be MUCH clearer about what you did & saw, and how the truck is put together. Lots of pics of the truck, engine, wiring, & mods would help. Including the details of how this 2ndry voltmeter is connected, so we can understand what your readings mean. Click this, read the caption, follow the links, and edit your signature:


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You also need to be very clear what you're talking about. The starter SOLENOID is on the starter motor; the starter RELAY is on the inner fender near the battery. The starter's large Red cable should always be hot (B+12V) and the Black block ground cable should always be at ground (B-0V).


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If the starter's small Red wire is always hot, it means the starter relay is welded internally:


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...or there's some other wire butchery going on, which we might be able to find in some clear pics that you post.


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The most-likely cause of the voltage dropping to 0 when a heavy load (like the starter or headlights) is applied is the battery terminals. Read all the captions in this photo album:


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