742/743 Fuel Pump Clicking

[onepoket]

So, I have figured out that I have an electric fuel pump in the 742/743 that I have. I call it a 743 because it has a reman v1702 engine and not the ford engine that came in the 742.

I have noticed that when I put the key in and turn to run, I hear a clicking, I am not sure if this is normal. I'm reasonably certain that this is coming from a relay that is in the dash panel. I think, but haven't had time to trace the wire, that the relay powers the fuel pump.

This hasn't caused a problem really so I thought the clicking was normal. The problem I have discovered is that after replacing the front lights with an LED light bar today, the light flickers. It seems to flicker at the same rate that the relay clicks, so I can only assume that the relay feeds all the accessory/lights.

A volt meter gave me 11.7v at the leads that power the old head lamp when switched on and .07 when switched off.

So, can anyone out there with more experience shed some light on what I should do? Is the relay bad? Should I rewire the accessory power without the relay?

Thanks for any help.

 

[Tazza]

Can you track where the ticking is coming from? Fuel pumps do make a ticking sound when they are working, hopefully it's just that causing the nise and the flicker will be from the power drain as the pump coil pulls inwards to make it pump.

 

[onepoket]

Can you track where the ticking is coming from? Fuel pumps do make a ticking sound when they are working, hopefully it's just that causing the nise and the flicker will be from the power drain as the pump coil pulls inwards to make it pump.

Tazza,

The clicking is definitely coming from the pump, I just checked it.

So, if that is operating normally then the relay is probably fine, but how do I get my lights to not flicker?

Do, I need to isolate my lights from the relay that is powering the fuel pump?

The wiring is way different than any diagram I have found. The two fuses in the left dash panel are not even connected to anything. The new relay the last guy added has a 20amp fuse attached but it was inside the dash, I had no idea until I took the dash apart to install my light.

I replaced the glow plugs and the thing is running great so I don't want to mess with the fuel pump if it sounds like it is working as expected.

Thanks.

 

[Tazza]

Tazza,

The clicking is definitely coming from the pump, I just checked it.

So, if that is operating normally then the relay is probably fine, but how do I get my lights to not flicker?

Do, I need to isolate my lights from the relay that is powering the fuel pump?

The wiring is way different than any diagram I have found. The two fuses in the left dash panel are not even connected to anything. The new relay the last guy added has a 20amp fuse attached but it was inside the dash, I had no idea until I took the dash apart to install my light.

I replaced the glow plugs and the thing is running great so I don't want to mess with the fuel pump if it sounds like it is working as expected.

Thanks.

It sounds like when the previous owner hooked up the pump, they did it on a power line that just didn't have enough current carrying capacity. Pumps really don't use lots of power.
Nor eason why you can't hook up a relay in the engine bay to power it.
You already have switched power to the pump, just use those wires to power the relay coil and then run a +ve wire to the relay and from the relay to the pump. The other end of the pump goes to ground.
Hopefully that will give you flicker free lighting.
One other thing i thought of, not sure how these run, if thre is any power spike prevention, you can install a diode across the two power wires to the pump, it will prevent power spikes coming back down the line when the coil de-energizes, but i'd think they would already have this fitted internally...
Kinda like this:
- +
----|<-----

The stripe is the negative side of a diode

 

[onepoket]

It sounds like when the previous owner hooked up the pump, they did it on a power line that just didn't have enough current carrying capacity. Pumps really don't use lots of power.
Nor eason why you can't hook up a relay in the engine bay to power it.
You already have switched power to the pump, just use those wires to power the relay coil and then run a +ve wire to the relay and from the relay to the pump. The other end of the pump goes to ground.
Hopefully that will give you flicker free lighting.
One other thing i thought of, not sure how these run, if thre is any power spike prevention, you can install a diode across the two power wires to the pump, it will prevent power spikes coming back down the line when the coil de-energizes, but i'd think they would already have this fitted internally...
Kinda like this:
- +
----|<-----

The stripe is the negative side of a diode

Ok, here is the update.

I got a bunch of diodes from Microcenter figuring one of them has got to work, the pack has all types silicon, zener, etc.

I tried wiring a silicon diode between the positive (which comes from the key run terminal) and the negative which was connected to the grounding lug on the engine. The first time I connected the + side of the diode to the + wire from the key to pump and obviously the - side of the diode to the ground wire. This caused the diode to explode essentially. I turned the key to run and I didn't immediately hear the pump start clicking, I heard a small pop within 1 second and then the pump started clicking. I looked in the engine bay to find the small parts scattered about.

The second try I wired the diode the other way around, this caused the diode to smoke but it never exploded. I turned it on for maybe 1 second and when I didnt hear the pump I turned it off.

So, I gave up and tried to rewire using a second relay. The first relay that was in the dash was not connected to the pump at all, the switched side of the key goes directly to the pump. Furthermore the dash relay was wired backwards where 87 and 30 were switched but the fuse was still on the 30 side. So, at first I was confused where the battery was coming from but then figured out what was going on. I fixed the goofy wiring and put the fuse where it should be on the battery side. This relay now only powers the switches that control my front and rear lights and two other switches that are currently not used.

In the engine bay I mounted a relay on the side of the frame and hooked it up to the pump, taking battery off of the solenoid that isn't the glow plug one. Basically that wire comes from battery->crank motor solenoid->solenoid under air cleaner. I used the wire that came off the key run position to trigger the relay. This works as expected.

The problem has been sort of fixed, the lights dont strobe anymore but they do pulse in intensity somewhat. I feel like there is somewhere I could wire a diode to smooth out the voltage when the pump ticks so that I can remove the pulsing.

Any thoughts on what type and where to put a diode that will accomplish this?

 

[foton]

Ok, here is the update.

I got a bunch of diodes from Microcenter figuring one of them has got to work, the pack has all types silicon, zener, etc.

I tried wiring a silicon diode between the positive (which comes from the key run terminal) and the negative which was connected to the grounding lug on the engine. The first time I connected the + side of the diode to the + wire from the key to pump and obviously the - side of the diode to the ground wire. This caused the diode to explode essentially. I turned the key to run and I didn't immediately hear the pump start clicking, I heard a small pop within 1 second and then the pump started clicking. I looked in the engine bay to find the small parts scattered about.

The second try I wired the diode the other way around, this caused the diode to smoke but it never exploded. I turned it on for maybe 1 second and when I didnt hear the pump I turned it off.

So, I gave up and tried to rewire using a second relay. The first relay that was in the dash was not connected to the pump at all, the switched side of the key goes directly to the pump. Furthermore the dash relay was wired backwards where 87 and 30 were switched but the fuse was still on the 30 side. So, at first I was confused where the battery was coming from but then figured out what was going on. I fixed the goofy wiring and put the fuse where it should be on the battery side. This relay now only powers the switches that control my front and rear lights and two other switches that are currently not used.

In the engine bay I mounted a relay on the side of the frame and hooked it up to the pump, taking battery off of the solenoid that isn't the glow plug one. Basically that wire comes from battery->crank motor solenoid->solenoid under air cleaner. I used the wire that came off the key run position to trigger the relay. This works as expected.

The problem has been sort of fixed, the lights dont strobe anymore but they do pulse in intensity somewhat. I feel like there is somewhere I could wire a diode to smooth out the voltage when the pump ticks so that I can remove the pulsing.

Any thoughts on what type and where to put a diode that will accomplish this?

have you looked at the voltage off the alt. voltage regulator is it pulsing there? Also a bad ground can cause fluctuations. Even a lack of load can cause peaking as the reg. charges then rests , I see this on a Chinese tractor I have the voltage pulses until I turn on a load then the voltage smooths out, try turning some lights and see what happens.

 

[onepoket]

have you looked at the voltage off the alt. voltage regulator is it pulsing there? Also a bad ground can cause fluctuations. Even a lack of load can cause peaking as the reg. charges then rests , I see this on a Chinese tractor I have the voltage pulses until I turn on a load then the voltage smooths out, try turning some lights and see what happens.

foton,

This happens when the engine is off with the key in the run position so that accessories can be turned on.

When the engine is running it has the same symptoms. I can actually hear the pump clicking and it syncs to the pulsing of the lights. Occasionally the pump will stop for a second or two and the lights will also stop pulsing. So, I'm thinking that the alternator doesn't have much to do with it. It is either the pump is stealing voltage from the lighting circuit when it cycles on or it is kicking back voltage as the pump cycles off. Not sure how to measure that exactly. But I think the diode Tazza suggested is part of the solution.

My only other thought is to try and really separate the power and ground connections for the pump and the key/accessories/lights so that they are not sharing any wiring, maybe there is some overlap in how it is all hooked up right now. But snow storm is on us so I will have to live with the pulsing since I need to plow with it.

Thanks

 

[foton]

foton,

This happens when the engine is off with the key in the run position so that accessories can be turned on.

When the engine is running it has the same symptoms. I can actually hear the pump clicking and it syncs to the pulsing of the lights. Occasionally the pump will stop for a second or two and the lights will also stop pulsing. So, I'm thinking that the alternator doesn't have much to do with it. It is either the pump is stealing voltage from the lighting circuit when it cycles on or it is kicking back voltage as the pump cycles off. Not sure how to measure that exactly. But I think the diode Tazza suggested is part of the solution.

My only other thought is to try and really separate the power and ground connections for the pump and the key/accessories/lights so that they are not sharing any wiring, maybe there is some overlap in how it is all hooked up right now. But snow storm is on us so I will have to live with the pulsing since I need to plow with it.

Thanks

if it is happening with the engine not running and all the electrical connections are good the only thing I can think of is the pump pulling to many amps for the circuit that is wired to. maybe use the wire that goes to the pump to activate a relay and wire in a fuse from the battery and switch the pump ,that will minimize the amps pulled on the start switch. Another thought could somewhere the power going to the start switch have a smaller gauge wire pieced in lowering the amount of amps to the switch? just a thought.