Do I need a diode or a new brain?

[ArdWrknTrk]

What I used to do on Darth, just never got around to adding a push button, was to take the blue fusible link off the starter relay's small stud and touch it to the battery side post on the relay until I heard the "hiss" from the vapor separator telling my I had filled the float bowls.

A push button connecting battery power to that point will run whichever pump (or the only pump) as long as it is held in.

I think the issue here is that this system (DS-II swapped AND an electric fuel delivery module in a Bronco tank) is using the (I) terminal for spark retard, and that is back feeding the (S) trigger.

I've been told the 300 never had an electric pump until EFI.

At first I had suggested the (I) terminal, but reconsidered that suggestion and deleted half my post.

There's little any of us can say without actually seeing all that's going on, as Gary is angling for.

 

[Tarheel Blue]

I was wrong! I should have said to jumper around the oil pressure switch, as shown in the diagram but not across the inertia switch. NOT across 85 and 86, which will do nothing.

I think what I'd do is to temporarily install a pushbutton switch across the oil pressure switch, push it with the key on and everything clear of the fan, and see what happens. I think the starter will engage as somehow things are connected to the R/LB wire going to the starter relay. That's just a guess, but that's my guess.

If it tries to start then jumper from 30 to 87 with the same switch and see what happens when you push it. If it tries to start the issue is on that side of the relay. If it doesn't try to start the issue is on the oil pressure switch side of the relay, which I think is impossible - unless there's another wire from 86 on the relay going some place else.

The last two suggestions are what I was trying to describe as my attempts in my first post. My wiring is exactly as shown in your last diagram. The oil pressure switch is a three pole. The description of its function is; Terminals P and S are normally closed, terminals P and I are normally open. When oil pressure reaches 2 - 4 psi, P and S are opened and P and I are closed Continuity testing has proven this to be true, so I’m assuming the switch is good.

I temporarily inserted the push button between P and I ( the left and right terminals in my diagram) and with the key in RUN, the pump ran but so did the starter. Thinking that I must be getting feedback to the start circuit through the oil pressure switch( terminal S), I decided to run “clean” power to the trigger of the pump relay (from battery to terminal 86). Starter still engages when pressing the prime button.

This is the point at which I thought of a diode as a fix/ bandaid, would still like to know why it seems to be needed. Something ain’t right.

[Tarheel Blue]

The last two suggestions are what I was trying to describe as my attempts in my first post. My wiring is exactly as shown in your last diagram. The oil pressure switch is a three pole. The description of its function is; Terminals P and S are normally closed, terminals P and I are normally open. When oil pressure reaches 2 - 4 psi, P and S are opened and P and I are closed Continuity testing has proven this to be true, so I’m assuming the switch is good.

I temporarily inserted the push button between P and I ( the left and right terminals in my diagram) and with the key in RUN, the pump ran but so did the starter. Thinking that I must be getting feedback to the start circuit through the oil pressure switch( terminal S), I decided to run “clean” power to the trigger of the pump relay (from battery to terminal 86). Starter still engages when pressing the prime button.

This is the point at which I thought of a diode as a fix/ bandaid, would still like to know why it seems to be needed. Something ain’t right.

This is the jumper/ splice that I made to insert the prime button.

The orange wire comes from the push button which gets its power from my unused fuse 15

The R/LB wire comes from the P terminal on the oil pressure switch

And the blue wire is the relay signal wire 86

Just did another test by disconnecting the R/LB wire from the splice and the pump runs w/o the starter engaging, so I must be getting feedback via the R/LB wire.

I know very little about diodes. If I were to install one on the R/LB wire, are there size/ amp/ ohm/ etc. considerations when purchasing?

[ArdWrknTrk]

This is the jumper/ splice that I made to insert the prime button.

The orange wire comes from the push button which gets its power from my unused fuse 15

The R/LB wire comes from the P terminal on the oil pressure switch

And the blue wire is the relay signal wire 86

Just did another test by disconnecting the R/LB wire from the splice and the pump runs w/o the starter engaging, so I must be getting feedback via the R/LB wire.

I know very little about diodes. If I were to install one on the R/LB wire, are there size/ amp/ ohm/ etc. considerations when purchasing?

You would want a rectifier diode, and if you're only using it to pull in the relay even 1/2 W should be okay.

You need to place it at the R/Lb wire before the splice.

The symbol for a diode appears like an arrow hitting a wall. This shows which way the current will flow.

The diode itself will likely be marked with a band close to one end to indicate 'polarity'

[Tarheel Blue]

You would want a rectifier diode, and if you're only using it to pull in the relay even 1/2 W should be okay.

You need to place it at the R/Lb wire before the splice.

The symbol for a diode appears like an arrow hitting a wall. This shows which way the current will flow.

The diode itself will likely be marked with a band close to one end to indicate 'polarity'

Thanks Jim!

In a quick search for 1/2 w rectifier diode, I have two questions.

W= watts? Or W= wave?

Rectifier seems to indicate changing from AC to DC?

What does that do for me?

I guess a third question. Would you see any issue if I were to place the diode between the ignition switch and the S terminal of the oil pressure switch?

[ArdWrknTrk]

Thanks Jim!

In a quick search for 1/2 w rectifier diode, I have two questions.

W= watts? Or W= wave?

Rectifier seems to indicate changing from AC to DC?

What does that do for me?

I guess a third question. Would you see any issue if I were to place the diode between the ignition switch and the S terminal of the oil pressure switch?

A rectifier diode as opposed to a Zener, Light Emitting, or other kind of diode.

They are somewhat optimized to minimize drop in the forward direction while not breaking down if overloaded against the gate.

Diodes by nature will only allow current to pass in one direction. To rectify alternating current you need to create a bridge of diodes. Half wave rectification will only pass the peaks of a sine wave while a full wave bridge rectifier (4 diodes) will invert the valleys giving you a constant series of peaks (kinda like whoops on a dirt track)

So a rectifier diode -in your case- will block your momentary switch from triggering the starter.

Get a diode rated at a minimum higher than your electric system should ever see. Say 18V... or more!

I'm trying to reply from the mail client on my phone. I can't see your picture ATM but I will revisit this thread when I get back from lunch.

[ArdWrknTrk]

Thanks Jim!

In a quick search for 1/2 w rectifier diode, I have two questions.

W= watts? Or W= wave?

Rectifier seems to indicate changing from AC to DC?

What does that do for me?

I guess a third question. Would you see any issue if I were to place the diode between the ignition switch and the S terminal of the oil pressure switch?

In this diagram?

You say P & S are normally closed, so you will be powering both if you switch I to either of them....

Like I said above you can simply run your switch across 30 & 87 of the relay.

This would power the fuel pump without affecting anything downstream on the trigger side (86 in this case)

Now that Radio Shack is dead I don't know any place locally to purchase "onesies" of any electronic component.

My suggestion would be the ubiquitous 1N400x series diode. These range from 1N4001 (@100V) to 1N4007 (@1,000V)

Any of this cheap and cheerful diode series are more than needed.

They all have a 1A rating and a forward drop of ~0.7V, which is fine with a regular Bosch style cube relay.

(In fact I can get a 12V cube relay to pull in with the stator output of my alternator that approximates 7V)

[Tarheel Blue]

In this diagram?

You say P & S are normally closed, so you will be powering both if you switch I to either of them....

Like I said above you can simply run your switch across 30 & 87 of the relay.

This would power the fuel pump without affecting anything downstream on the trigger side (86 in this case)

Now that Radio Shack is dead I don't know any place locally to purchase "onesies" of any electronic component.

My suggestion would be the ubiquitous 1N400x series diode. These range from 1N4001 (@100V) to 1N4007 (@1,000V)

Any of this cheap and cheerful diode series are more than needed.

They all have a 1A rating and a forward drop of ~0.7V, which is fine with a regular Bosch style cube relay.

(In fact I can get a 12V cube relay to pull in with the stator output of my alternator that approximates 7V)

Installed a 1N4001 diode today placing it in an in-line mini fuse holder for protection in the engine bay.

Key in RUN, push the momentary contact switch and the fuel pump comes on WITHOUT the starter engaging.

Tomorrow I need to run some tests to figure out how many seconds it takes to fill the bowl in the ol’ YFA so that I can get a good squirt or two out of the accelerator pump so that she starts without a lot of crank time.

[Gary Lewis]

Installed a 1N4001 diode today placing it in an in-line mini fuse holder for protection in the engine bay.

Key in RUN, push the momentary contact switch and the fuel pump comes on WITHOUT the starter engaging.

Tomorrow I need to run some tests to figure out how many seconds it takes to fill the bowl in the ol’ YFA so that I can get a good squirt or two out of the accelerator pump so that she starts without a lot of crank time.

Excellent!!!

[BigBrother-84]

Installed a 1N4001 diode today placing it in an in-line mini fuse holder for protection in the engine bay.

Key in RUN, push the momentary contact switch and the fuel pump comes on WITHOUT the starter engaging.

Tomorrow I need to run some tests to figure out how many seconds it takes to fill the bowl in the ol’ YFA so that I can get a good squirt or two out of the accelerator pump so that she starts without a lot of crank time.

Happy for you that problem solved!

This reminds me why I LOVE my mechanical pump...