installing electric fuel pump on my 76

[who444444]

My fuel pump started to leak and so now is the time to install electric pump.
Decided to use the 85 prelude pump and found one at rock auto for under $30 ( I think )
I want to power it through a relay so I found a junkyard toyota 30 amp relay.
Here is how I wired it. (this is for the folks that might not have figured it out yet, everyone else skip on down )

I tapped into 2 of the 5 amp circuits as I wanted to separate the switching and the load on the relay. Both circuits are switched circuits only hot with key on.
So first circuit positive to relay post 85 and ground to relay post 86 ( run this ground to the oil pressure sending unit and land with the existing wire on unit )
second circuit positive to relay post 87A (on my relay or 87 on a 4 post relay) and positive to the pump from relay post 30. Negative of pump is grounded to frame.
post 85 and 86 connect inside of relay through a coil that when energized connects OR disconnects 87 and 30

I needed a normally closed relay that when energized disconnects and here's why.
when no power to relay, 87 and 30 are connected ( that's OK because there is also no power feeding the pump because the key is not on )
With key on and engine is not running oil pressure light is on because sending unit is grounded and now relay is grounded (and energized ) and relay now disconnects 78 and 30 (the pump circuit.)
When engine runs and oil pressure light goes out it is because the sending unit losses ground. When relay losses ground 87 and 30 are connected and pump is powered. (Whew!)

I run a single carb and I dont think I will need the pump running to start my bike because there is a lot of fuel in the carb float bowl.
If it turns out I'm wrong I will put a switch in the ground wire going to oil sending unit to temp brake circuit and close relay before starting.
Why run like this through relay you say? Just a kinda safety feature so if the bike is not running the fuel stops flowing just like a manual pump.
Anyway, had to cobble up a bracket to mount pump and also block off opening where old pump was. Made that today and hope to finish mounting all tomorrow.
Here's some pics. flat black on the bracket and once I know the pump is not dead out of the box it will be flat black too. To match the rest of the bike. :smilie_happy:

 

[Ansimp]

Nice :good:

 

[zman]

Well thought out plan and nice bracket too, looking forward to the results. opcorn:

 

[dan filipi]

Nice design but....but......the beauty of an electric pump is it fills the bowl before cranking.
I hope it works out how you have it set up though. It makes for a good safety.

 

[Joep]

nice setup... my thoughts and less wiring... oil sending light is okay but you are changing resistance in the oil circuit this way.. I soul have gotten a 30 amp 4 post normally open relay.. run key switch power through 86/85 and battery to 30 and pump to 87.. direction of where pump is wired makes no difference.. I would fuse the battery lead to have slight protection.. then pump runs when key is on and not when off.. not sure why you are looking at two fuse circuits. This is from my work with relays...

 

[who444444]

Having it working with oil pressure is a safety feature in case bike goes down and engine stops (with key still on ).
At that point pump will stop and less chance of even more problems (fire and such )
Using two separate circuits was just something I did without any real reasoning but does allow for on the road repair to get home if I have a problem with either circuit do to unrelated short.
(by jumping as needed to power both from just one circuit)

Dan, I am hoping that the weber keeps enough fuel in the bowl to get started before pump comes on.
I did start it once without the manual pump attached to bike and was successful.
Should know tomorrow.
dave

 

[slabghost]

That will work if the bike doesn't sit for too long. Been a few times my truck has had to crank a while to refill the carb for starting. It still has the mechanical pump.

 

[skiri251]

Good idea to use oil pressure switch for safety!
But I too have that empty carb issue so the pump must be turned on before cranking.
So you use brake switch to override?

I was going to use both mech. and elec. pumps in parallel but discouraged by the fact that fuel tee connectors cost $10 shipped. After all, the pump cost only $17 shipped. So now thinking about using elec. pump only.

 

[dan filipi]

How about using the neutral switch ground to run the pump for start up, then have the oil pressure switch supplying ground after startup.
Through relays of course.
Just thinking because I should do this and I need pump action before starting.

 

[skiri251]

Ahhh..

In any case I still need to buy normally closed relay $$$$. LOL

 

[dan filipi]

skiri251 » Thu May 01, 2014 8:03 am[/url]":3dz85p46]
Ahhh..

In any case I still need to buy normally closed relay $$$$. LOL

Need a cube relay with an 87a connection.
Those are cheap.

 

[who444444]

sorry about bad terminology not brake light switch, but switch to break continuity in ground to pressure switch allowing pump to run before starting engine.
Dave

 

[Steve83]

On the '85 Limited fuel injected 1200 engine I'm working on, the pump runs for a second or two when the ignition is turned on, then constantly once the engine is running. There is also a tip sensor that shuts off the pump if the bike goes down. The pump relay is controlled by the computer. The tip sensor is powered by 12 volts from the "RUN" switch, and simply disconnects the ground circuit of the main relay when tipped, shutting off the computer - and fuel pump. There is a schematic in the Gallery, in the Honda Service Supplement 1985 GL 1200L, under Repair Manuals- GL 1200, or here's one I drew in Photoshop that's easier to read, but not as detailed:

EFI Schematic

• Steve83
• May 1, 2014

A delay circuit might be tricky to build, but the tip sensor should be an easy install. I got mine on Ebay for about $10.

 

[who444444]

that sounds great I may look into the tip sensor very soon.
Nice schematic.
dave

 

[dan filipi]

That IS a nice schematic.

Steve, do you have a link to the tip sensor you mentioned?
I bought one a couple years ago but it doesn't look very trustworthy.

 

[who444444]

got pump installed and running.
However I do like the tip switch idea and ordered a used one on ebay for 7.50
When I get it I'll wire it up to my relay and change relay to normally open and use switch to cut power to pump. Thanks for pointing that idea out Steve. Here's pic of before and after flat black treatment.
dave

 

[slabghost]

Could wire it through the start bypass at the start button switch that bypasses the ballast at start up. Then the pressure switch could take over.

 

[Ansimp]

Oil pressure switch is earth with no oil pressure, you can use a changeover relay but not the best way to go. On commercial application I use a Hobbs switch which has both nc and no contacts and replace the oil light switch with it. If the relay fails you will have the fuel pump constantly running. I like the idea of a tilt switch much better. The other option for Skiri is to use a mini momentary switch for priming only.

 

[mike in idaho]

who444444 » Wed Apr 30, 2014 5:33 pm[/url]":1sm2ezuj]
My


I needed a normally closed relay that when energized disconnects and here's why.
when no power to relay, 87 and 30 are connected ( that's OK because there is also no power feeding the pump because the key is not on )
With key on and engine is not running oil pressure light is on because sending unit is grounded and now relay is grounded (and energized ) and relay now disconnects 78 and 30 (the pump circuit.)
When engine runs and oil pressure light goes out it is because the sending unit losses ground. When relay losses ground 87 and 30 are connected and pump is powered. (Whew!)

What happens if, after the oil light switch opens, the relay continues to get a ground through the oil light bulb socket?

 

[who444444]

Oil pressure light socket is I think a isolated ground and gets its ground from the pressure switch. Anyway its working now as I am on a test ride now and using my phone to post. I agree the tilt switch is the way to go and have already bought one on eBay.
dave