Grandma Griff
Alaska
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He really does set things on fire. We don't leave him alone with the welding equipment.
Griff in Fairbanks' Wife
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VintageMopar
Missouri
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Welcome Ms Griff....
A word about electric fuel pump wiring. Keep in mind you don’t want a ignition on fuel pump running gas on you while your rig is upside down in a ditch. GM used an oil pressure sending unit in the early days so if motor was not running it would shut off. (Vega) . Chrysler used an asd relay that was pcm controlled as did ford . Have to think a bit about how to control on non computer engine. Maybe alternator triggered control relay on 13-14 volts?
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Griff in Fairbanks
AK
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VintageMopar wrote:A word about electric fuel pump wiring. Keep in mind you don’t want a ignition on fuel pump running gas on you while your rig is upside down in a ditch. GM used an oil pressure sending unit in the early days so if motor was not running it would shut off. (Vega) . Chrysler used an asd relay that was pcm controlled as did ford . Have to think a bit about how to control on non computer engine. Maybe alternator triggered control relay on 13-14 volts?
Yes, absolutely. That's why I specified a momentary, spring-loaded switch for the 'primer' bypass.
For a while, manufacturers were installing inertial 'crash' switches that would turn off the fuel pump. However, there was a tremendous amount of 'false positive' triggering -- many times the number of actual crashes.
I've been trying to figure out a good way of having the fuel pump only running when the engine is running. (Eric is going to need a manual cut-off switch for when he's running on propane.)
My problem is K.I.S.S. but reliable. Everything I've come up with so far involves complex circuits, too many components, too much expense, electronics, and so forth.
Oil pressure sensing still seems to be the best ... old school but that's often the best. There's a way to set up your motorhome for both gauge and indicator (aka 'idiot') light. Leeann's done it to her motorhome. We could 'tee' off the indicator light circuit but the there's a time lag between engine start and sufficient oil pressure.
If I come up with something simple, inexpensive, and reliable, I'll try to remember to let everybody known.
In the meanwhile, everybody should remember to turn off the ignition (key) switch if you're involved in an accident.
1970 Explorer Class A on a 1969 Dodge M300 chassis with 318 cu. in. (split year)
1972 Executive Class A on a Dodge M375 chassis with 413 cu. in.
1973 Explorer Class A on a Dodge RM350 (R4) chassis with 318 engine & tranny from 1970 Explorer Class A
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ronfisherman
SE Michigan
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![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/cool.gif "cool")
WELCOME !!!!!
Grandma Griff wrote:New member here Griff's wife.
Decided to join to keep an eye on him.
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TreeSeeker
San Diego
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Griff wrote:For a while, manufacturers were installing inertial 'crash' switches that would turn off the fuel pump. However, there was a tremendous amount of 'false positive' triggering -- many times the number of actual crashes.
This is what my 1996 Ford Explorer has. It only triggered once--during very hard breaking. I didn't know about these switches at the time so I had to have it towed to a shop to find out why it wouldn't start after that.
The switch is easy to reset if you know where it is, so it is decent solution. I still have the Explorer and that is the only time it has triggered. Maybe others were too sensitive.
If you wanted to use the oil pressure sensor to control the fuel pump I suppose you could use a timer to turn on the pump until the oil pressure gets up. As you said, however, complicated.
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Griff in Fairbanks
AK
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Early versions of the inertial crash switches were too sensitive. I believe they've improved them to decrease false positives, based on an apparent reduction in reports. (Or, people have learned about them and how to reset them.)
In the early versions, any kind of aggressive driving -- hard braking, hard acceleration, hard cornering -- could trigger them. Rough roads -- washboards, pot holes, frost heaves -- caused the same problem. In some cases, a shopping cart bumping into your vehicle in a parking lot was enough.
I have heard a reliable report of someone swerving to avoid a collision. In that case, the car died during rush hour in the middle of an interstate highway. While the person's car wasn't hit, it did lead to multi-vehicle collisions and pileups.
I quit counting the number of people I've helped by resetting their switch. Almost all have tried to pay me. Three went as far as later leaving an envelope on my windshield, for a total of $80.
The inertial switch must be manually reset. If you think you have one ... or just want to make sure ... read your owner's manual or contact a dealership's customer service. In addition to knowing how to reset it, you need to know where it is. In sedans, they're typically located in the trunk, usually near the gas tank fill outlet. In vans and pick-ups, they're usually under the dash on the passenger's side. (I've had several people say, "Oh, that's what that is.")
Regardless of whether you have the switch or not, ALWAYS turn off the ignition (key) switch if you're involved in an accident. Provided you can do so safely. (If in doubt, get everyone well away from the vehicle to a safe place.). Turning off the ignition switch will prevent the electric fuel pump from spewing fuel out a broken fuel line.
Even if you have a mechanical fuel pump, turning off the ignition switch will de-energize major portions of the electrical system and reduce the possibility of an electrical fire due to sparks and short circuit from crash damage. (Turn off the headlights also but leave the emergency flashers on.)
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Griff in Fairbanks
AK
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Any electric fuel pump power circuit (beyond an ignition switch connection and maybe primer switch) is going to involve a continuous duty relay.
Gauge == sensor == variable resistance == variable voltage.
Indicator ('idiot') light == switch == on/off == relatively stable voltage.
It's worth noting virtually all motor vehicle gauges are 5-6 volt devices. (There's a voltage regulator in OEM instrument clusters that reduces the vehicle's nominal 12VDC to 5-6VDC for the gauges.). This, along with the variable resistance/voltage, creates issues when using an oil pressure sensor for determining if an engine is actually running. (At a minimum, you'd need an electronic voltage comparator in addition to a continuous duty relay.)
Note: The same issue exists with using the alternator as an indicator of engine operation. The alternator's voltage regulator (the one most people are familiar with) turns the alternator on and off in response to sensed system voltage. So, the alternator is likewise a problematic indication of whether the engine is running or not.
Oil pressure indicator lights alert a driver to a sudden, catastrophic drop in oil pressure. Oil pressure gauges require the driver to notice the drop in oil pressure and are more useful for noticing changes over time.
Back in the 50's and 60's (and probably into the 70's and 80's), race car builders installed both oil pressure switches and sensors. Because the switches/sensors were an either-or situations, this required plumbing to install both.
Computerized engine management units only need to know if there is or is not sufficient oil pressure so a switch is preferable. On the other hand, consumers strongly preferred gauges even if they didn't know how to read them or what the hell the needle position meant.
So, manufacturers began producing components that combined both a switch and sensor in a single unit. These combined units is the key to what Leeann has done, in terms of both an oil pressure gauge and indicator (warning) light.
Here's a very good Allpar article on the subject.. The article is reprinted from Mopar Action magazine, originally written and subsequently updated by Richard Ehrenberg. (Richard Ehrenberg is extremely knowledgeable on motor vehicle electrical systems, particularly in terms of Dodge and other Mopar vehicles ... I tend to trust anything he's written.)
If you look about two-thirds way down in that article, you'll see "Michael D. Griffin" cited -- that's me.
* This post was
edited 02/18/18 04:24pm by Griff in Fairbanks *
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Griff in Fairbanks
AK
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BTW - one of the things on my (lengthy) to-do list is to see if a Ford voltage regulator will work with a Dodge alternator. (Yes, I'm an unrepentant heretic.)
I want both gauges and indicator (warning) lights in MLP for oil pressure, engine temperature, and electrical system. How to do that is already established for oil pressure and installation/modification shouldn't take more than two hours. (With most of the two hours spent looking for tools and supplies.)
Ford voltage regulators have a terminal specifically for an 'ALT' indicator light. If the Ford regulator and Dodge alternator will cooperate, that's solved as well. (Voltmeter rather than ammeter ... I've repeatedly expressed my disdain for ammeters in motor vehicles.)
All that remains is engine (coolant) temperature. Need to dig back in history to see how 'TEMP' indicator lights worked way back when, if they existed. (It's far enough back that people may have simply relied on steam spewing out of the radiator to indicate overheating.)
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StingrayL82
Nampa, Idaho
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Griff in Fairbanks wrote:BTW - one of the things on my (lengthy) to-do list is to see if a Ford voltage regulator will work with a Dodge alternator. (Yes, I'm an unrepentant heretic.)
I want both gauges and indicator (warning) lights in MLP for oil pressure, engine temperature, and electrical system. How to do that is already established for oil pressure and installation/modification shouldn't take more than two hours. (With most of the two hours spent looking for tools and supplies.)
Ford voltage regulators have a terminal specifically for an 'ALT' indicator light. If the Ford regulator and Dodge alternator will cooperate, that's solved as well. (Voltmeter rather than ammeter ... I've repeatedly expressed my disdain for ammeters in motor vehicles.)
All that remains is engine (coolant) temperature. Need to dig back in history to see how 'TEMP' indicator lights worked way back when, if they existed. (It's far enough back that people may have simply relied on steam spewing out of the radiator to indicate overheating.)
If AMC could take a Ford ignition system and use a GM alternator and make it work, I don’t see why you couldn’t Frankenstein your own mix and match parts and make them work.
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Griff in Fairbanks
AK
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StingrayL82 wrote:If AMC could take a Ford ignition system and use a GM alternator and make it work, I don’t see why you couldn’t Frankenstein your own mix and match parts and make them work.
Sometimes, there's bottomless chasm between should work and does work.
I recall one hilarious episode where two people who worked for me tried to connect a computer tape backup unit from one manufacturer to a desktop from another manufacturer. The connection at both ends was RS232 and they verified straight-thru versus roll-over cable. (I appreciated them trying it on a desktop rather than risking the big AT&T 3B2 Unix box.)
The result was smoke and ozone pouring out of the (new, just out of the box) tape unit. They thought they were in deep doodoo. I quickly pointed out to them the attempt made sense to me. I also pointed out the Small Computer Technical Center mission statement includes trying things just like what they'd done.
(We promptly fried two more tape units to verify it wasn't a one-off event ... and it revealed a contract violation by the contractor.)
So, until I've actually tried it and it's been in use for a while, I don't trust anything. (It was two years before I trusted my marriage.)
* This post was
edited 02/18/18 04:59pm by Griff in Fairbanks *
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