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matte

Posted 2016-11-23 1:25 AM (#526909)
Subject: Fuel Pump Relay

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Location: Sydney, Australia

Ok I'm going through absolutely everything to work out why my car is spluttering and stalling every so often. Things like timing, vapour lock, heating of fuel pump..

So I have a pulse pump mounted near the tank. Yes I'd rather the mechanical one but from circumstances I'm not able to use one.. I'm going to mount a relay for the pump so I'll know I have that area covered. The setup I have at the moment is Positive wire from the pump to a switch under the dash and the runs from there to the ignition. Later down the track I will use an oil pressure switch but for now I'm using the switch set up.

Do I use a 4 pin relay?

And does the relay wiring go
1: pos straight from battery to one of the relay pins
2: Ground wire for relay
3: pos wire from relay to pump
4: pos wire from ignition to my on/off button for the pump

Is this correct?

56D500boy

Posted 2016-11-23 1:58 AM (#526912 - in reply to #526909)
Subject: RE: Fuel Pump Relay

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Here is an example of the four pin Bosch relay that I probably used on an Audi so I could relay the fuel pump directly to the battery:

Whichever brand relay you use, it should be good quality and MUST have this diagram on it:

Where 85 and 87 are the trigger (switch) circuit and 30 is the battery and 87 is the power to the fuel pump.

Make sure that you set it up with an inline fuse:

1. Make the connections from the trigger wires (your switch) to the relay using the insulated 22 to 18 gauge 1/4" female spade connectors. The completed insulated female connectors should be attached to the male connectors on the low voltage side of the relay. On mine, this was spades 85 and 86.
2. With the new fuse holder empty (no fuse installed), connect the fuse holder to the + battery and terminal 30 on the relay using a ring connector on the battery end and an insulated 12 to 14 gauge 1/4" female spade connector at the relay end. Without putting a fuse in the fuse holder, put the ring connector under the battery cable bolt nut (take the nut right off, slip on the ring connector and then put the nut on) and attach the battery cable to the + battery post again (don't break the post by over torquing the nut). Attach the other end with the insulated spade connector to pin 30 of the relay.
3. Find a nice comfortable location for the new power cables in a corrugated plastic sheath.
4. Test the lengths of the new 14 gauge red fuel pump power cable to the position of the relay and the brown 14 gauge fuel pump ground cable directly to the negative terminal of the battery or a suitable location. Trim wire length, as appropriate. Leave a bit extra but not too much - the longer the wire, the more the voltage drop.
5. Make a 14 gauge insulated female spade connection on the end of the red power wire and connect to the power out terminal of the relay (87 on the relay I used).
6. Make a 14 gauge ring connection to the end of the 14 gauge brown ground wire and attach to the negative terminal of the battery (remove the nut from the bolt, slip the new fuel pump ground over the bolt, add the nut and tighten (being careful not to overtighten).
7. Add a 15 amp fuse to fuse connector.

REFERENCE: http://forums.quattroworld.com/s4s6/msgs/24327.phtml

matte

Posted 2016-11-23 2:34 AM (#526913 - in reply to #526909)
Subject: RE: Fuel Pump Relay

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That is absolutely an awesome set of instructions. I'm good with some electrics but plays and diodes always elude me.

Is my crappy diagram correct from your instructions?

(IMG_6099.JPG)

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IMG_6099.JPG (215KB - 159 downloads)

56D500boy

Posted 2016-11-23 11:21 AM (#526942 - in reply to #526913)
Subject: RE: Fuel Pump Relay

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matte - 2016-11-23 2:34 AM That is absolutely an awesome set of instructions. I'm good with some electrics but plays and diodes always elude me.
Is my crappy diagram correct from your instructions?

Diodes are just like check valves in hydraulics. Flow only goes one way.

Your diagram is close. It's good on the battery to 30 with the fuse in between and then 87 to the fuel pump positive. The fuel pump negative doesn't have to go all the way back the battery. Grounding to the car frame should be good.

Where you went a bit off is the 85 and 86 terminals with the switch. You need switched power, not just a switched circuit. The relay needs the power to pull the connection between the 30 and the 87 closed. You need to get power to your switch off the ignition switch (something that is ON when you turn the key to "ON"). Then run that power to the input side of your switch. Run the output of the switch to the 85 (or 86) terminal of the relay and ground the other terminal, i.e. 86 if you connected the switch to 85 or 85 if you connected the switch to 86.

Not sure what electric fuel pump you are using but remember that carburetors don't need much more than 6 psi (if I recall correctly). Fuel injection fuel pumps like the ones on my Audis run much higher pressures, i.e. 85 psi. I think that would kill carb, even with the floats trying to shut the needle valve.

Good luck.

Edited by 56D500boy 2016-11-23 11:22 AM

matte

Posted 2016-11-23 4:52 PM (#526979 - in reply to #526909)
Subject: RE: Fuel Pump Relay

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Yeah my carb only likes 3-5 psi.

I thought my switch setup on the last diagram didn't make sense.. I thought it might of been some crazy thing the relay is able to do

Is this all ok now?

(IMG_6100.JPG)

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IMG_6100.JPG (244KB - 141 downloads)

ttotired

Posted 2016-11-23 5:13 PM (#526985 - in reply to #526909)
Subject: Re: Fuel Pump Relay

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Matt
Don't 1/2 ass it as you will never "do it properly", get an oil pressure switch ect (they are not expensive) and do it properly now.

You do know why an oil switch is used, don't you?

If your fuel pump is a "Facet", (about a 2" block) it should be able to easily keep up with your engine and if its working now, I doubt that putting the relay in (although, not a bad idea) will achieve anything

Have you thought about finding a mechanic near you that's into old school stuff and letting them have a crack at it?

Generally, throwing parts at a car to try and fix it turns into an expensive exercise, where a tradesman might be able to sort it out in an hour or so

matte

Posted 2016-11-23 5:58 PM (#526992 - in reply to #526985)
Subject: Re: Fuel Pump Relay

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ttotired - 2016-11-23 5:13 PM

Matt
Don't 1/2 ass it as you will never "do it properly", get an oil pressure switch ect (they are not expensive) and do it properly now.

You do know why an oil switch is used, don't you?

If your fuel pump is a "Facet", (about a 2" block) it should be able to easily keep up with your engine and if its working now, I doubt that putting the relay in (although, not a bad idea) will achieve anything

Have you thought about finding a mechanic near you that's into old school stuff and letting them have a crack at it?

Generally, throwing parts at a car to try and fix it turns into an expensive exercise, where a tradesman might be able to sort it out in an hour or so

Yeah I know the oil switch is for safety/kill when the engine stops from an accident..

I've now had 2 old school mechanics do work on it. First one took me for a ride and took $6K for below average work and overcharging plus a mark up on parts at 200%. The second mechanic was good but I'm finding things that he said he did but hadn't done. He thought it was the fuel pick up because it was pretty clogged but it's not because it's still doing it but only every so often. He also left grease all over my carpet and marks on the seat. I've also run out of money for a mechanic to try and work out what's going on. If I can eliminate some little things first, I might get lucky. Old school mechanics are hard to find now. When I first started looking, I was ring my area then out further..

I was reading that Facet pumps can get hot and a relay will keep them from overheating.. I'm just trying a few cheaper things first. I've got a new pick up strainer, a relay and heat wrap for rubber fuel lines(engine bay gets really hot). I'm thinking it could be vapour lock when driving slow or in traffic because if I switch off the car when hot, it takes ages for it to start again because of fuel starvation.

Sydney is just not a place to break down. Besides the arsehole attitudes of the people, it's also very hilling with no places to roll to(no parking on the side).

Edited by matte 2016-11-23 7:11 PM

Powerflite

Posted 2016-11-24 1:09 AM (#527034 - in reply to #526992)
Subject: Re: Fuel Pump Relay

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I like your solution because it is a good addition even if it doesn't solve the problem. But you may want to solve the "really hot" part of it as well. Make sure that it is staying under 190 F.

Also, my Barracuda would stumble and stall, usually while going uphill. It turned out to be a partial blockage within the fuel line. So be sure to use compressed air to blow out your fuel line when you get it disconnected. There is a lot more pressure available with compressed air to knock out any obstruction that may be there. Just be sure to disconnect it from the tank first or you will blow up the tank and destroy it.

56D500boy

Posted 2016-11-24 1:41 AM (#527038 - in reply to #526979)
Subject: RE: Fuel Pump Relay

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matte - 2016-11-23 4:52 PM Yeah my carb only likes 3-5 psi. I thought my switch setup on the last diagram didn't make sense.. I thought it might of been some crazy thing the relay is able to do

Is this all ok now?

Diagram looks good now.

matte

Posted 2016-11-24 1:42 AM (#527039 - in reply to #527034)
Subject: Re: Fuel Pump Relay

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Powerflite - 2016-11-24 1:09 AM

I like your solution because it is a good addition even if it doesn't solve the problem. But you may want to solve the "really hot" part of it as well. Make sure that it is staying under 190 F.

Also, my Barracuda would stumble and stall, usually while going uphill. It turned out to be a partial blockage within the fuel line. So be sure to use compressed air to blow out your fuel line when you get it disconnected. There is a lot more pressure available with compressed air to knock out any obstruction that may be there. Just be sure to disconnect it from the tank first or you will blow up the tank and destroy it.

Um oops I was such an idiot and had brain freeze. I did a quick shot of compressed air into the fuel tank line coming from the pick up. It was enough to make a back pressure and blow fuel back out! My car was doing it mainly on hills too and it even only had to be the slightest angle. The last mechanic said the pickup was so blocked he was amazed it ran at all. The tank has been drained twice but he's not sure if crap is still getting about. The pick up also doesn't have a strainer on the end so I've got one coming.

Yeah it gets pretty hot. It was a 96 degree Fahrenheit day. I was stuck in city traffic and it was edging towards 220-230. Driving around with air flowing over the radiator it will sit on 190-205... I'll check timing because she is also a bit of a big to get moving, get a radiator and block flush then if all else fails, get a bigger cored radiator..

Edited by matte 2016-11-24 1:43 AM

matte

Posted 2016-11-24 1:44 AM (#527041 - in reply to #527038)
Subject: RE: Fuel Pump Relay

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Location: Sydney, Australia

56D500boy - 2016-11-24 1:41 AM

matte - 2016-11-23 4:52 PM Yeah my carb only likes 3-5 psi. I thought my switch setup on the last diagram didn't make sense.. I thought it might of been some crazy thing the relay is able to do

Is this all ok now?

Diagram looks good now.

:)

Thanks mate. I'll be doing that on the weekend...

lonesome mopar

Posted 2016-11-27 12:35 PM (#527272 - in reply to #526909)
Subject: Re: Fuel Pump Relay

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<p>just passing by and I thought I might help as I too have switched to an electric pump for my '58 Belvie. I have wired my relay in the way shown in the draft below and it works: I also used a five pin relay, using only one of the double pins side available.</p>

Edited by lonesome mopar 2016-11-27 12:53 PM

(relay 1.jpg)

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relay 1.jpg (68KB - 160 downloads)

lonesome mopar

Posted 2016-11-27 12:50 PM (#527274 - in reply to #526909)
Subject: Re: Fuel Pump Relay

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In case you need to know which side of your relay to connect to, simply take two live wires from the two poles of the battery and close alternatively the 85 86 87. Not the 30.
Once you will here a click inside the relay, these are the two poles to use.
One of the two (indifferent) takes the wire coming from the ignition switch / and safety switch - and the other has to be grounded.
The other two are the 30 (live feed wire from the + battery (or starter relay positive) and the other goes to the fuel pump. That has to be grounded / or its negative wire has to be grounded.

56D500boy

Posted 2016-11-27 1:11 PM (#527277 - in reply to #527274)
Subject: Re: Fuel Pump Relay

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lonesome mopar - 2016-11-27 12:50 PM In case you need to know which side of your relay to connect to, simply take two live wires from the two poles of the battery and close alternatively the 85 86 87. Not the 30..

There is no guess work or trial and error involved. The 85 and 86 are for the 12V trigger signal. 30 is the auxilliary power in and 87 it the power out to the device that you want to relay.

ttotired

Posted 2016-11-27 4:42 PM (#527286 - in reply to #526909)
Subject: Re: Fuel Pump Relay

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Yes exactly
A couple of cautions though, most relays are set in the pin patter above, but for some stupid
reason, they also make relays with 86 and 87 swapped (lonesome mopars picture) also, some
relays have a quenching diode across the coil (trigger) and if you connect positive and earth (switching wires) on
there backwards, it will kill the relay.

Picture above as a resistor across the coil, if it was a diode, there would be a line going across the little box at one end.

Most relays don't have either, but I like the resistor ones

56D500boy

Posted 2016-11-27 5:01 PM (#527291 - in reply to #527272)
Subject: Re: Fuel Pump Relay

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lonesome mopar - 2016-11-27 12:35 PM I thought I might help as I too have switched to an electric pump for my '58 Belvie. I have wired my relay in the way shown in the draft below and it works: I also used a five pin relay, using only one of the double pins side available.

I am sort of liking the oil pressure switch as a safety switch (to shut off the fuel pump in the event of an accident), *BUT* I don't like the idea of having to crank the engine enough to build sufficient oil pressure before the fuel pump is triggered. It's like I would like a fuel pump on switch that is used to prime the fuel system and start the car and then, afterwards, the oil pressure switch is used as the safety.

Your sketch (which I like with the exception of the above comment)

Edited by 56D500boy 2016-11-27 5:02 PM

Powerflite

Posted 2016-11-27 7:41 PM (#527312 - in reply to #527291)
Subject: Re: Fuel Pump Relay

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You could use an oil pressure safety switch just as it is shown, but install a parallel line that bypasses it with an on/off switch. So before you crank your car over, switch it on. After it is started, switch it off and the pump will still run because you now have oil pressure.

56D500boy

Posted 2016-11-27 9:03 PM (#527318 - in reply to #527312)
Subject: Re: Fuel Pump Relay

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Powerflite - 2016-11-27 7:41 PM

You could use an oil pressure safety switch just as it is shown, but install a parallel line that bypasses it with an on/off switch. So before you crank your car over, switch it on. After it is started, switch it off and the pump will still run because you now have oil pressure.

Exactly.

lonesome mopar

Posted 2016-11-28 6:26 AM (#527337 - in reply to #526909)
Subject: Re: Fuel Pump Relay

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Well said. :-)
as a matter of fact I have a simple press button that close the circuit just to start the engine.
I didn't put it in the drawing as it might have resulted complicate to read. :-))

matte

Posted 2016-11-28 4:26 PM (#527400 - in reply to #527337)
Subject: Re: Fuel Pump Relay

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Thanks to everyone for the help. Relay is mounted and all wiring done.

lonesome mopar - 2016-11-28 6:26 AM

Well said. :-)
as a matter of fact I have a simple press button that close the circuit just to start the engine.
I didn't put it in the drawing as it might have resulted complicate to read. :-))

Where did you put the wiring for the oil switch? Did you use a 3 prong oil switch?

ttotired

Posted 2016-11-28 4:40 PM (#527404 - in reply to #526909)
Subject: Re: Fuel Pump Relay

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No thought of hooking up an oil bypass system (as in, power feed from the start switch) so it has power while cranking?

Your car is also carburetted, which means once its had its shot of fuel, the fuel bowl will hold enough fuel to allow it to keep running.

You could also use a "Tachometric" relay

Details here http://holdenpaedia.oldholden.com/Tachometric_Relay

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