New Guy here, anyone seen my paddle

[26ftcobraBBF]

Hi all,

UPDATE:

I've got the Cobra MH all back together, 2 new fuel pumps, removed universal pump that was hanging off the frame rail, removed the romex that someone ran from the fuse panel to the universal pump.

With all properly installed and grounds clean, I still have to power to the pumps.

I have power in and out of the inertia switch, so where do I go from here? Jumper the solenoid? Jumper the oil pressure switch? Help!

Ok 2nd update... Tell me if I've done wrong please but.....

I didn't get any continuity between the fuse link on the "I" terminal so I cut it out and put a 20amp glass fuse in its place🤷.

Also jumped two wires on the oil pressure switch.. turned the key on and boom I know have a pump working... Here's the thing though when the pump was running the relay was clicking on and off like a blinker.. I shut it off right away, and am now consulting you guys. What do I do? Why is the relay clicking on and off like a blinker? What do I do next? I'm almost there. Thank you.

[ArdWrknTrk]

Ok 2nd update... Tell me if I've done wrong please but.....

I didn't get any continuity between the fuse link on the "I" terminal so I cut it out and put a 20amp glass fuse in its place🤷.

Also jumped two wires on the oil pressure switch.. turned the key on and boom I know have a pump working... Here's the thing though when the pump was running the relay was clicking on and off like a blinker.. I shut it off right away, and am now consulting you guys. What do I do? Why is the relay clicking on and off like a blinker? What do I do next? I'm almost there. Thank you.

You didn't have continuity from the 'I' terminal to where?

Look at the wiring diagram in the '86 EVTM (documentation>electrical>EVTM>1986> fuel systems>7.5l dual tanks)

You'll see the pink/black wire bypasses the fuel pump relay & the resistor, jumping directly to -Z- the selector switch.

So, fuselink 'T' is only going to pass current when the starter is engaged....

I don't think any glass fuse is advisable. Replacement fusible links are available at any auto parts store.

Usually these crimp right on.

Most often the relay is chattering because you (or someone before you) set up a feedback loop and the output is raising the ground side of the engagement coil.

Poor connection at g112?

Without any potential it drops out, and then it will pull back in, ground side goes high and it drops again, lather, rinse, repeat....

You need to examine what's happened at the relay.

Maybe the relay has failed? Try taking it out and see if it will pull and hold when it's isolated from the socket.

Maybe the socket is all corroded? That's not too uncommon.

Take it off the firewall and look underneath.

 

[26ftcobraBBF]

You didn't have continuity from the 'I' terminal to where?Look at the wiring diagram in the '86 EVTM (documentation>electrical>EVTM>1986> fuel systems>7.5l dual tanks) You'll see the pink/black wire bypasses the fuel pump relay & the resistor, jumping directly to -Z- the selector switch.So, fuselink 'T' is only going to pass current when the starter is engaged....I don't think any glass fuse is advisable. Replacement fusible links are available at any auto parts store.Usually these crimp right on.Most often the relay is chattering because you (or someone before you) set up a feedback loop and the output is raising the ground side of the engagement coil.Poor connection at g112?Without any potential it drops out, and then it will pull back in, ground side goes high and it drops again, lather, rinse, repeat....You need to examine what's happened at the relay.Maybe the relay has failed? Try taking it out and see if it will pull and hold when it's isolated from the socket.Maybe the socket is all corroded? That's not too uncommon.Take it off the firewall and look underneath.

There wasn't any continuity through the fuse link on the wire that connects to the I terminal.To clarify ( because I may have jumped the oil pressure sender incorrectly) on the rear center of the motor, just outside in intake manifold there are two devices located in close proximity to each. Between the two of them there are three wires that share a harness. One unit has two wires going to it a blue, and I think rd/wht. The other unit has one boot shaped connector with just one wire that's the same red/ wht.... So I jumpered the two red/why... Because I was thinking the blue came from the solenoid.

 

 

Hindsight question, with everything put back as it should be. With the key in the on/ run position is the fuel pump on, or is it only on while cranking, and engine actually running?.

 

 

 

 

On Tue, Dec 8, 2020, 1:40 AM ArdWrknTrk [via Bullnose Enthusiasts Forum] <redacted_email_address> wrote:

 

 

 

 

 

[ArdWrknTrk]

The little tin can looking thing on top is the oil pressure sender.

The two wire device on the side is the safety switch.

You can see the wire colours in the diagram above.

It seems two red/yellow wires.

Edit: oil pressure should be white/red (again -shown above- as part of the gauge cluster)

The pump should never run with the engine not turning.

Pumps prime the system if the starter is engaged and the cutoff relay closes when oil pressure is above 5 psi or so.

That and the inertia switch should should cut off the pump(s) if you hit something hard or end up on the roof.

 

[ArdWrknTrk]

The little tin can looking thing on top is the oil pressure sender.

The two wire device on the side is the safety switch.

You can see the wire colours in the diagram above.

It seems two red/yellow wires.

Edit: oil pressure should be white/red (again -shown above- as part of the gauge cluster)

The pump should never run with the engine not turning.

Pumps prime the system if the starter is engaged and the cutoff relay closes when oil pressure is above 5 psi or so.

That and the inertia switch should should cut off the pump(s) if you hit something hard or end up on the roof.

The '85 system must vary from '86 in some ways.

Let me try to find another EVTM diagram....

Ah yes!

'85 still has the older switching relay instead of running power straight through the switch on the climate control console.

 

[ArdWrknTrk]

The '85 system must vary from '86 in some ways.

Let me try to find another EVTM diagram....

Ah yes!

'85 still has the older switching relay instead of running power straight through the switch on the climate control console.

And here you see 'Z' jumping back to the selector.

[26ftcobraBBF]

The little tin can looking thing on top is the oil pressure sender.The two wire device on the side is the safety switch.You can see the wire colours in the diagram above.It seems two red/yellow wires.Edit: oil pressure should be white/red (again -shown above- as part of the gauge cluster)The pump should never run with the engine not turning.Pumps prime the system if the starter is engaged and the cutoff relay closes when oil pressure is above 5 psi or so.That and the inertia switch should should cut off the pump(s) if you hit something hard or end up on the roof.

Ok so I screwed up. So I should have just jumpered the two wires on the safety switch, not one from the safety, and the other from the sender? Maybe that's why my relay was clicking like a blinker, and the pump was kicking on and off with the click.

 

So say I jumper it the right way, then it starts as it should and runs, that would tell me that the safety switch is bad correct? Replace and ready to roll...in a perfect world..

 

 

On Tue, Dec 8, 2020, 3:46 AM ArdWrknTrk [via Bullnose Enthusiasts Forum] <redacted_email_address> wrote:

 

 

 

[Gary Lewis]

You guys are doing well, but I will say I agree that your jumper wasn't applied correctly. As you said, it should be on the oil pressure/safety switch. Having included the instrument cluster voltage regulator is probably what caused the relay to come in and drop out as the ICVR's contacts opened and closed.

I think if you jumper that switch it'll run. And you could even drive it briefly that way, realizing that in an accident the pump will keep adding fuel to any fire. But it would let you check the system out.

[ArdWrknTrk]

I wouldn't just jumper the wires,.

I would test across the switch for continuity with the engine running.

That's really the only way to 'prove' the switch is faulty.

What was your oil pressure reading when you had your wires crossed?

The gauges are only meant for ~5V.

Notice 57 is common ground for cutoff and selector relays.

A bad connection at S112 or G112 is going to make things interesting.

[Gary Lewis]

I wouldn't just jumper the wires,.

I would test across the switch for continuity with the engine running.

That's really the only way to 'prove' the switch is faulty.

What was your oil pressure reading when you had your wires crossed?

The gauges are only meant for ~5V.

Notice 57 is common ground for cutoff and selector relays.

A bad connection at S112 or G112 is going to make things interesting.

Won't you have to be pretty fast to measure the switch's resistance/continuity with the engine running if it is bad? I'd think pulling the jumper would tell the tale. If the engine dies the switch is bad.