Electrical diagram or schematic needed

[Lowflyn]

After rebuilding the engine (now 502), adding an enclosed cooling system (very kwell) - I'm finall ready to fire and no elec fuel pump. Jumpered 12v to pump it works, removed relay, it tested good. 12v to fire the relay is there yet nothing on the other side of relay feeding the pump..... Do not know where it runs from?? Circuit breakers tested good too.
Trying not to have to tear the entire harness apart (hate unwrapping elec tape)to trace wiring to individual sources manually. Work smarter NOT harder - I just need a schmatic or a diagram....

Any hints on where????

Thanks in advance - U guys have always been great!!

[mrfixxall]

i have has in the past if you dont have the distributor dead nuts on it wont fire,back fire or anything..try spraying some flameable carb cleaner in the throttle body to see if it will at leaste fire,itf it does than your almost spot on..their are also fuses in that box with the relays..

[hdsadey]

Check to see if it has an oil pressure switch. It cuts off the electric pump if the oil pressure suddenly drops. If the oil pressure isnt up yet it wont allow the relay to go to ground turning on the fuel pump. Could also be a bad switch (if it has one). Should be down on the side of the block just above the oil pan.

[gcarter]

The safety switch, if it has one (oil pressure operated) are known to fail, but they can be wired across (not a good idea, but sometimes you have to).

[MOP]

This may help also check hte second link there may be some other things of help.

http://www.marinemechanic.com/site/page264.html

http://www.marinemechanic.com/site/page19.html

[Lowflyn]

Safety switch?? Activated by the oil pressure gage??? Again - I would have to open up the entire harness to trace that one. Presure gage is connected - a very old ugly style sending unit - yet Where's this safety switch at??
Attached is an old photo - yet shows my configuration - elec pump - circuit breaker and starter relay housing... Damn this was an ugly engine - plus the water line exhaust thru transum.... That cost me $$$$$

[gcarter]

If you have a safety switch, it'd be located on the port lower rear of the block and manifolded together with the oil pressure sending unit. There would be three wires connected to it, a purple wire from the ignition, a wire from the starter relay, and a wire to the electric pump.
It's a normally open switch that temporarily supplies power to the pump from the starter signal while it's cranking, and then, when the oil pressure comes up, the switch closes, and power is supplied to the pump from the ignition.

[Lowflyn]

Only the one old sending unit, single wire.... Looks like I'm tearing the harness apart to see what goes where :(

[MOP]

After seeing your engine color check this link you "may" find some help!

http://www.marinemechanic.com/site/page130.html

[gcarter]

Not so fast!
Take a look here:
http://www.marinemechanic.com/site/page250.html


http://www.marinemechanic.com/site_image/TBOLT-IV-WIRING.gif

[gcarter]

Notice this is for an Alpha, so disregard the shift cutout switch.
If you have an electric pump, it needs a safety switch. They're sold by Holley and are easy to wire in.

[gcarter]

One other thing I'd add, is, if you do use a fuel pump safety switch, don't tie into the purple line going to the coil for the power to the pump.
Instead, run a seperate line from the ignition switch, which doesn't go through the ignition safety switch (tethered switch).
I've read there're things related to the ignition system that can kill the fuel pump safety switch. I've experienced this myself, but at the time, I didn't relate it to taking the power from the coil.
Here's a link to a PDF w/instructions for installation.

http://www.holley.com/data/Products/Technical/199R9680-1rev.pdf

Note how it's wired!!!!!!!
You can also notice they're made for Holley by Faria instruments.

Here's Holley's site page;

http://www.holley.com/12-810.asp

There're a few places to buy them from that'll be a little cheaper, but not by much.

[GeneD]

For the life of me...I can't spot the electric fuel pump in that diagram!:eek:

[gcarter]

For the life of me...I can't spot the electric fuel pump in that diagram!:eek:

Gene, it's not in the diagram, but he was asking for an engine wiring harness diagram. He says an electric pump has been added and wants to know how to wire in a safety switch. If the diagram is utilized along w/the Holley information I also added, it'll be clear where to wire in the pump and safety switch.......or at least it is to me...:boggled:

[mattyboy]

George

I am pondering the wiring for my setup. I have gotten a merc wiring harness,bracket and engine pig tail. I will not need certain wires as my setup doesn't call for them. I plan on using an unused wire to connect the IGN Switch "ON" to the Norm Open on the switch, then a wire from the Norm Closed on the switch to the "S" post on the remote started solenoid. a fused wire from the Common on the switch to the electric fuel pump "+" connection.
So in a normal state with the switch unactivated the common and Norm Closed are shorted allowing current to flow once the key is turned to start and the starter solenoid puts 12 volts across to the starter and the "s" post. Once the pressure builds and the switch activates the common and the Norm Open are shorted allowing current to flow from the "on" of the ign switch to the pump.

do I have this straight??

Thanks

[gcarter]

George

I am pondering the wiring for my setup. I have gotten a merc wiring harness,bracket and engine pig tail. I will not need certain wires as my setup doesn't call for them. I plan on using an unused wire to connect the IGN Switch "ON" to the Norm Open on the switch, then a wire from the Norm Closed on the switch to the "S" post on the remote started solenoid. a fused wire from the Common on the switch to the electric fuel pump "+" connection.
So in a normal state with the switch unactivated the common and Norm Closed are shorted allowing current to flow once the key is turned to start and the starter solenoid puts 12 volts across to the starter and the "s" post. Once the pressure builds and the switch activates the common and the Norm Open are shorted allowing current to flow from the "on" of the ign switch to the pump.

do I have this straight??

Thanks

Yes, that's correct. It's handy having a spare wire or two from the harness available to use for other things.
On the TR, I won't have an alarmsystem, so I'm using that wire for the oil temperature sender.

[mattyboy]

Thanks George

yes I have the trim sender wire and the alarm wire that will be unused

[hdsadey]

Here's a diagram for a 4.3 liter with an electric pump!

[Lowflyn]

That is the elec pump - Yet missing a relay, circuit breaker and I'm not sure what else is envolved with my set up. Just started tearing the harness apart - once opened - start tracking who, what and to where - Oh What fun :(

[MOP]

Look back by the distributor or down by the oil filter adapter there should be a safety switch with two tangs, the purple wire goes to it then from the other tang to the ignition. You have an OMC setup which is similar but slightly different than a Merc setup. None of the diagrams thus shown show the fuel/oil safety switch, I looked in my OMC manual but could not find an electric pump setup. With the electric fuel pump the low oil warning and ignition cut may be an all in one item having more than one wire going to it. As a temp to test things out you could supply voltage to the pump directly, it should be a switched circuit. There are many boats even here on this board that have no safety inline, I always have suggested installing one. On the pump kits that we supply only the higher volume pumps come with a switch, reason being they will force fuel past the float valves and flood the engine with fuel.

[Lowflyn]

The oil switch was suggested earlier - yet not on mine. Only one elect oil pressure (one wire) sender used. I have tested the pump, the inline relay and circuit breaker - all checked good.

12V from ignition sw hits the coil of the relay is good, grounding is good yet the 12v supply - that would be going through relay switch side to pump is not.

Now I need to find where or what that wire is connected to.. Which means tearing the harness apart. Nothing difficult - just very time consumning. Especially since this is a freshly rebuilt engine that I have not fired yet!! I'm eager to get back to the water - not pulling elec tape!!!

[mrfixxall]

The oil switch was suggested earlier - yet not on mine. Only one elect oil pressure (one wire) sender used. I have tested the pump, the inline relay and circuit breaker - all checked good.

12V from ignition sw hits the coil of the relay is good, grounding is good yet the 12v supply - that would be going through relay switch side to pump is not.

Now I need to find where or what that wire is connected to.. Which means tearing the harness apart. Nothing difficult - just very time consumning. Especially since this is a freshly rebuilt engine that I have not fired yet!! I'm eager to get back to the water - not pulling elec tape!!!


how many oil pressure switches do you have on the engine? in order for the relay to work all it needs is a ground trigger to turn the pump on.. a bosh 5 pole relay is probably is what is used...pole 30 should have a constant 12 v pole 87 should be going to the fuel pump supply wire,pole 86 should be going to a oil pressure switch and pole 85 should be a ignition + 12v..87a is not used..(center pole) the relay only needs 500 ma to trigger it so if you have any extra wires in the harness that were not going to anything that matches the color of the wires going the the fuel pump relay ground that wire and see if the fuel pump comes on..

[Lowflyn]

Thanks Mr Fixx - the relay is as you have discribed. It's the 12v supply - pin 30 on relay that's in question, also not knowing where it's coming from. I'll look for any spare wires - once all the tape is removed. They should really out law elec tape on boats :)