"91 150 Starter Relay...?
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Trailering
Joined: Apr 2013
Posts: 18
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"91 150 Starter Relay...?
Starting problems: now just a click when turning key. Starting difficulty similar to tired battery, worse when engine warm/hot. I began at battery, terminals, connections to relay which fell apart when backing nuts for connections, replaced relay(with backup I keep in glove box, new), no change. Replaced starter motor, wrapped small exhaust leak at pipe connection close to starter motor thinking heat, no change. Key turn always been sticky needing assist to turn back from starter motor enguage, was used to it, research had me pulling wheel for that aluminum arm thing, it was fine, then down to engage switch on column they say falls apart, that's fine...except a little sticky from dust/grease/grime, cleaned all that up. Now thinking back to starter relay, but what else? Perhaps something signalling the relay isn't? Screwdriver jump over relay and engine kicks like it should, runs perfect, shuts off with key, but only a click when turning key normally to start. Thinking relay gone bad from sitting in glovebox a few years but how likely? Any other wire/connector/fuse, etc between key and relay I need to check? Please no "81 pin ohm check to such 'n such computer" advice, last Ford was a '74 250, pure analog, I'm barely proficient with that multi meter thing.
Cargo Master
Joined: Aug 2021
Posts: 2,258
Likes: 742
From: Maryland
How old is the battery? When you say you "began at battery", do you mean you replaced it?
What type of battery terminals do you have? If you have the type that sandwich the wire under a clamp, they're most likely the problem.
Is the main ground wire that runs from the battery negative terminal, to the engine block (V8) or starter mounting bolt (straight 6) original? That cable can look ok but be corroded inside.
The starter is grounded through that cable.
Take a test light or volt meter, and check for 12 volts at the small gauge wire that goes to the "s" terminal of the fender mounted starter relay, when the key is turned to the start position.
The fender mounted starter relay is grounded to the inner fender by it's mounting screws and backing plate.
I would check those things in that order.
What type of battery terminals do you have? If you have the type that sandwich the wire under a clamp, they're most likely the problem.
Is the main ground wire that runs from the battery negative terminal, to the engine block (V8) or starter mounting bolt (straight 6) original? That cable can look ok but be corroded inside.
The starter is grounded through that cable.
Take a test light or volt meter, and check for 12 volts at the small gauge wire that goes to the "s" terminal of the fender mounted starter relay, when the key is turned to the start position.
The fender mounted starter relay is grounded to the inner fender by it's mounting screws and backing plate.
I would check those things in that order.
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Trailering
Joined: Apr 2013
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Battery good, I'll check terminals type, ground to engine block the only thing left. That said the starter motor turns strong when relay jumped, so perhaps the "s" terminal or relay grounding the problem. Will report back. Thanks!
Hotshot
Joined: Jul 2020
Posts: 10,471
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From: Near Salt Lake City
If not, it will click or buzz and not start
Use at least one bolt with a nut on the backside is what we used to do
That way you can get the solenoid "tight" to the inner fender and the ground will be sufficient
i ain't rite
Joined: Mar 2005
Posts: 65,511
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From: Marlboro Mental Hospital.
another vote for bad ground on relay.
unbolt relay from fender and use a piece of sandpaper or scotchbrite pad to clean it to a shiny surface. do the same for the relay mounting surface. bolt it back together and it should be fine.
unbolt relay from fender and use a piece of sandpaper or scotchbrite pad to clean it to a shiny surface. do the same for the relay mounting surface. bolt it back together and it should be fine.
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Trailering
Joined: Apr 2013
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Reporting back: sanded/prepped and mounted solenoid/relay on side panel, ultra solid grounding! Solved nothing as still the same "click" and no turnover. Screwdriver jumps, turns strong, runs normal, so thinking another bad solenoid/relay? BTW, I am finding both terms used to describe the black round thing that the batt pos wires up to which is adding to my confusion. More confusion: dude at Oreilly suggests/sells me a "relay", as in the little black cube with six or seven flat pins that plugs in somewhere, stating those fail and that could be the problem, cant find this relay location anywhere on the truck(under dash nor under hood), thinking he's confused on the model year, I'm a 1991. Is there even such a relay anywhere on this truck?
More Turbo
Joined: Sep 2012
Posts: 739
Likes: 256
From: Zimmerman, MN
Screwdriver jump over relay and engine kicks like it should, runs perfect, shuts off with key, but only a click when turning key normally to start. Thinking relay gone bad from sitting in glovebox a few years but how likely? Any other wire/connector/fuse, etc between key and relay I need to check? Please no "81 pin ohm check to such 'n such computer" advice, last Ford was a '74 250, pure analog, I'm barely proficient with that multi meter thing.
Problem is, you don't seem to know where to turn next, as by your own admission (italicized above) you're not comfortable using a VOM.
I only see three possible ways for you to address this:
1. Learn how to use your VOM (this assumes you know how to read wiring diagrams).
2. Grab a buddy to do this for, or with, you.
3. Pay someone to do this for you.
Whatever you chose, good luck!
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Trailering
Joined: Apr 2013
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I figured out the simple uses of the multimeter, what next? assuming I have no friends
Everything rewired into the relay EXACTLY as it was, I am certain of that. So, test with VOM is to verify powert from start selector to "S" terminal? If no power wouldn't the solenoid/relay simply make no "click" at all?
Everything rewired into the relay EXACTLY as it was, I am certain of that. So, test with VOM is to verify powert from start selector to "S" terminal? If no power wouldn't the solenoid/relay simply make no "click" at all?
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Lead Driver
Joined: Jun 2021
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good point, the fender to to the stud to the battery is a poor path in general, so making sure its enough is good
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Trailering
Joined: Apr 2013
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Ok, now miffed by the location of the start relay, as in the little black cube thing with half a dozen flat pins off the bottom. Everyone/everything says left/driver side under the hood up against fender. There's a plastic hangar like box with three relays in it, none of which even suggests start relay, and pin pattern not even close. Ohh, 1991 F-150 5.0, XLT Lariat if that matters.
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Trailering
Joined: Apr 2013
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No solenoid on the starter, just on the passenger side fender. The solenoid on the fender produces only a "click" when key turned to start, no turn over. When solenoid jumped with screwdriver engine fires right up as it should. So, if solenoid jump results in solid turnover and fire, key turn prodices very audible click from solenoid, what is left? all connections cleaned, solid ground, nothing left...except replace start relay? as in the little black cube with six or seven flat pins on the bottom, but where does it plug in???
Cargo Master
Joined: Aug 2021
Posts: 2,258
Likes: 742
From: Maryland
An electrical relay uses a low amperage circuit, to control a high amperage circuit.
The fender mounted relay is there so you don't have a spark show at your steering column mounted ignition switch. The arcing takes place inside the fender mounted relay, or outside of it, if you use a screwdriver to complete the circuit.
A solenoid uses one form of energy to control another form of energy. Think vacuum operated EGR valve. Electricity activates the EGR control solenoid, and controls the vacuum, which then flows to the EGR valve, and moves it.
Starters have a starter mounted solenoid, which uses electrical current to move the starter gear forward, into the flywheel. Electricity moving a gear=solenoid. Two different types of energy.
The fender mounted relay is there so you don't have a spark show at your steering column mounted ignition switch. The arcing takes place inside the fender mounted relay, or outside of it, if you use a screwdriver to complete the circuit.
A solenoid uses one form of energy to control another form of energy. Think vacuum operated EGR valve. Electricity activates the EGR control solenoid, and controls the vacuum, which then flows to the EGR valve, and moves it.
Starters have a starter mounted solenoid, which uses electrical current to move the starter gear forward, into the flywheel. Electricity moving a gear=solenoid. Two different types of energy.