electric fuel pump oil pressure switch pins gauge

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wlecat

wlecat

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I put in an electric fuel pump in my Barracuda, the fuel pump company suggested that I feed the power to the pump through an oil pressure switch as a fail-safe measure (good idea I thought). So Iinstalled a 3 prong oil pressure switch to feed the pump and send a signal to the OP gauge. It works, but unfortunately it pins the gauge.

Is the unit not designed to work with the gauge?

Is it the wrong OP sensor/switch?

Or do I need a capacitor or something prior to the gauge?
 
I think I figured this one out on my own.
Are there other locations on a 340 to install an additional oil pressure sensing device?
 
That would work fine for a fuel injected system because the engine would quit right away if you lost oil pressure.
A carbed motor will have enough gas in it to keep running long enough to detroy itself before it ran out of gas.
 
Be specific......................

1---WHAT are we workin on, IE make, model and year

(What you have in your avatar doesn't look like any A body, to me, and even if it did...............)

2---WHAT exactly did you use for a 3 prong oil sender? For all I know you have a sender that should be feeding a warning light, not a gauge.

3---How do you know you have the sender wired correctly? Where did you figure this out? Can you/ did you measure the resistance of the sender for the gauge section, even with no pressure?
 
67Dart273 said:
Be specific......................

1---WHAT are we workin on, IE make, model and year

(What you have in your avatar doesn't look like any A body, to me, and even if it did...............)

2---WHAT exactly did you use for a 3 prong oil sender? For all I know you have a sender that should be feeding a warning light, not a gauge.

3---How do you know you have the sender wired correctly? Where did you figure this out? Can you/ did you measure the resistance of the sender for the gauge section, even with no pressure?
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1967 Ply Barracuda with a '69 340, yeah I figured out it's just a switch not a sending unit, that's why it pegs the gauge, doubt I can measure the resistance with the tools I have.
Will need to use both the sensor switch AND a sending unit, as I asked before is there another location on a 340 to install an additional oil pressure sensing device?
Thanks for the responses.

No the avatar is a 76 Plymouth Arrow (LOL), modified way ahead of it's time in 1980. When I was young and foolish...I'm older now.
 
It beats the hell outta me why fuel pump companies tell people to do this. Stupidest thing I ever heard and you're not the first I've heard them advise to do so. As long as there's fuel in the carburetor, the engine will run, oil pressure or not. If you want to wire anything to the oil pressure switch, make it the ignition feed.
 
wlecat said:
I see your point but it's better than nothing
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How do you figure that? If it has enough fuel in the carb to run itself to death in the event of low oil pressure what good is it going to do shutting the pump off?? I can't quite understand your logic here? Best bet would be to hook the ignition up thru a low op switch.....but hell, what do I know....
 
The manufacturers recommend an oil press switch controlling the fuel pump as a safety feature. If you are in a bad accident, the engine usually dies. If a fuel line is ruptured, the pump keeps running and makes for a nice fire.
 
skykeith said:
The manufacturers recommend an oil press switch controlling the fuel pump as a safety feature. If you are in a bad accident, the engine usually dies. If a fuel line is ruptured, the pump keeps running and makes for a nice fire.
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No, not quite. What happens if you wreck and the engine STAYS RUNNING?

The thing you want if you are concerned about this is maybe a crash switch, or "both" crash switch and OP switch.
 
inkjunkie said:
How do you figure that? If it has enough fuel in the carb to run itself to death in the event of low oil pressure what good is it going to do shutting the pump off?? I can't quite understand your logic here? Best bet would be to hook the ignition up thru a low op switch.....but hell, what do I know....
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The oil pressure ignition cut off makes better sence, but then you have to crank it till you get oil pressure before it'll start. (Unless you put a manual bypass in also)
Then you have to remember to (Arm) it again after the car starts, or it's all for nothing again.

In my oppinion, the best thing you can use for this is a warning light/buzzer or both on the old idiot light style sender.
If you loose oil pressure, it makes the warning light/buzzer or both activate.
The light will be on, and the buzzer will scream till the oil pressure comes up, but you will have instant oil pressure loss warning with audio and video alert.
I have done it this before and it worked really well.

But what do I know? :D
 
67Dart273 said:
No, not quite. What happens if you wreck and the engine STAYS RUNNING?

The thing you want if you are concerned about this is maybe a crash switch, or "both" crash switch and OP switch.
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If the engine stays running, you haven't ruptured the fuel system.
 
skykeith said:
If the engine stays running, you haven't ruptured the fuel system.
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WTF you would want the engine to stay running after a crash is beyond me, and this statement is NOT true. You could easily have a situation where a line was "cracked" spewing fuel all over a hot engine, and the fan blowing it all over hell.

I tipped a van over on it's side in a bizzare fog/ ice thing and the dammed thing kept right on running. I wasn't hurt, and managed to reach up and turn off the key, then crawl out the high side door.
 
67Dart273 said:
WTF you would want the engine to stay running after a crash is beyond me, and this statement is NOT true. You could easily have a situation where a line was "cracked" spewing fuel all over a hot engine, and the fan blowing it all over hell.

I tipped a van over on it's side in a bizzare fog/ ice thing and the dammed thing kept right on running. I wasn't hurt, and managed to reach up and turn off the key, then crawl out the high side door.
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yupp neighbors diesel truck kept on running after a real good side/front impact; the battery was laying on the frame sparking like crazy
 
67Dart273 said:
WTF you would want the engine to stay running after a crash is beyond me, and this statement is NOT true. You could easily have a situation where a line was "cracked" spewing fuel all over a hot engine, and the fan blowing it all over hell.

I tipped a van over on it's side in a bizzare fog/ ice thing and the dammed thing kept right on running. I wasn't hurt, and managed to reach up and turn off the key, then crawl out the high side door.
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Sorry I upset you, but I never said I'd want the engine to keep running. I didn't know you were that averse to a simple safety solution that might save a life. Also a vehicle laying on it's side loses oil pressure pretty fast.
 
Simple enough to solve. Wire the pump with a momentary 12V from the "start" position on the ignition switch. That way, it will bust right off without having to build oil pressure. Ford has the best in the department for accidents, far as I'm concerned with their fuel pump inertia switch. One could just as easily be wired into one of our older cars with no problem. With the two together, you just took care of both problems. I am sure someone will be along to shoot that down, too. Have a good day.
 
skykeith said:
Sorry I upset you, but I never said I'd want the engine to keep running. I didn't know you were that averse to a simple safety solution that might save a life. Also a vehicle laying on it's side loses oil pressure pretty fast.
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I'm not adverse, and I'm not upset. I'm simply saying that an OP switch is poor protection. There are lots of accidents where a vehicle is not necessarily on it's side, or even so might "keep" OP. And there are CERTAINLY cases where a fuel line could be damaged and the engine still run, very dangerous.

I'm simply trying to get through that a crash switch, either instead of or in addition to an OP switch, is probably much better protection.
 
WAIT! What were we talking about? Oh that's right...Wlecat wanted to know if there were other locations on a 340 to install an additional oil pressure sensing device? or do I need to T it? ;)
 
wlecat said:
WAIT! What were we talking about? Oh that's right...Wlecat wanted to know if there were other locations on a 340 to install an additional oil pressure sensing device? or do I need to T it? ;)
Click to expand...

:D Easiest to T it.
 
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