Aux tank fuel pump saga continues
- Thread starter Kigiin
- Start date
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Did you feel the wires leading to the pump after doing this to make sure they are not heating up? Upping fuse sized to get rid of the problem is not a good idea unless you know that the particular part draws that much amps and the wiring is up to it.
At this point I would be for pulling the whole tank and re-installing carefully. You've had it out a couple times IIRC, maybe someone got sloppy reconnecting tubes and lines after having to pull it out again.
and X2 on what Christo said. Hot wires and a gas tank are not a good mix.
and X2 on what Christo said. Hot wires and a gas tank are not a good mix.
You obviously have too much resistance of some kind: Electrical or possibly vapor. Do you notice a rush of inbound (to the tank side) air when you pull the tank filler cap? Just wondering if you are getting a high vacuum accumulated because of poor venting that is causing the fuel pump to work that much harder?
Or as you mentioned its possible you have a bare wire or bad connection that results in sporadic shorting...
Or as you mentioned its possible you have a bare wire or bad connection that results in sporadic shorting...
Okay time to do some troubleshooting.
Get one of those inline fuse holders and put it right at fuel pump with a 15amp fuse. Keep your 25 amp fuse where ever it is. If 15amp does not blow, move it to next connection in wiring until it blows, then examine the wiring between it and the last test point.
If it does blow when attached directly to pump. Get a new pump. With a 25amp fuse that is 300 watts of power, you do NOT want that kind of power in a fuel tank, for any reason. Really!! Think how hot a 300 watt light bulb gets.
2 amps is 24watts, even plugged lines should not increase it that much.
Do not pass go, fix this before you do anything else, please.
Get one of those inline fuse holders and put it right at fuel pump with a 15amp fuse. Keep your 25 amp fuse where ever it is. If 15amp does not blow, move it to next connection in wiring until it blows, then examine the wiring between it and the last test point.
If it does blow when attached directly to pump. Get a new pump. With a 25amp fuse that is 300 watts of power, you do NOT want that kind of power in a fuel tank, for any reason. Really!! Think how hot a 300 watt light bulb gets.
2 amps is 24watts, even plugged lines should not increase it that much.
Do not pass go, fix this before you do anything else, please.
- Thread starter
- #26
Agree - upping the fuse size on a pump rated at only 2 amps is a very bad idea. A 10 amp fuse should be more than sufficient.
My mechanic and I are totally going over things tomorrow. I never did drop the tank as the silicone spray has solved the squeaking problems to date. However to re-look at the plumbing and wiring doesn't require dropping it as everything is accessible with it still bolted in.
I am not really gettin a huge amount of air rush when opening the cap - there is some but really no more than the OEM set-up. As far as the main and aux tank vents, I had assumed this was only to return vapor turning to liquid back to its respective tank and not to relieve pressure as the system is closed with the tight fitting cap. Someone had suggested trying a vented gas cap, but don't even know where I would get one that fits, plus my mechanic said it would throw the CEL.
My mechanic and I are totally going over things tomorrow. I never did drop the tank as the silicone spray has solved the squeaking problems to date. However to re-look at the plumbing and wiring doesn't require dropping it as everything is accessible with it still bolted in.
I am not really gettin a huge amount of air rush when opening the cap - there is some but really no more than the OEM set-up. As far as the main and aux tank vents, I had assumed this was only to return vapor turning to liquid back to its respective tank and not to relieve pressure as the system is closed with the tight fitting cap. Someone had suggested trying a vented gas cap, but don't even know where I would get one that fits, plus my mechanic said it would throw the CEL.
Ok...so it sounds like you can rule out high vacuum potential. On to the electric circuit and fuel pump. Just so you don't feel bad you're not the only one that, at times, seems like you're in the proverbial swirl of the flush with your rig 
- Thread starter
- #28
After looking over everything again, and re-visiting when the fuses are blowing and pumps have been burning out, my mechanic and I concluded the location of the pump is causing the problem.
It's externally mounted on the backside of the tank and at the tank's mid level line. When the tank is full, the pressure of fuel in the tank feeds the input of the pump without a problem. I haven't had any problems transferring the first 20 gallons or so from aux to main when the aux is full (it holds 45 gallons). However when the aux tank is half full or less (red line in drawing), we believe there isn't enough pressure and/or the pumps we have been using don't provide the suction necessary to continue to extract fuel. So as the pump works harder and harder to transfer the last 20 gallons or so of fuel, fuses blow, or if I have a big enough fuse in there, the pump eventually burns out.
I am not sure why this isn't a problem for other Front Runner owners, unless this was a design change recently.
My mechanic and I think there are two solutions: lower the pump to be level with the bottom of the tank or purchase a pump that has enough suction power to deal with being mounted at the mid line of the tank.
It's externally mounted on the backside of the tank and at the tank's mid level line. When the tank is full, the pressure of fuel in the tank feeds the input of the pump without a problem. I haven't had any problems transferring the first 20 gallons or so from aux to main when the aux is full (it holds 45 gallons). However when the aux tank is half full or less (red line in drawing), we believe there isn't enough pressure and/or the pumps we have been using don't provide the suction necessary to continue to extract fuel. So as the pump works harder and harder to transfer the last 20 gallons or so of fuel, fuses blow, or if I have a big enough fuse in there, the pump eventually burns out.
I am not sure why this isn't a problem for other Front Runner owners, unless this was a design change recently.
My mechanic and I think there are two solutions: lower the pump to be level with the bottom of the tank or purchase a pump that has enough suction power to deal with being mounted at the mid line of the tank.
I can't see how that can cause it, unless it is a really tiny pump. Once the system is primed, any pump should have enough capacity to be able to draw up the fluid that small height.
- Thread starter
- #31
Well I am not sure myself, so want to do a test to see if a new pump can draw gas out of a small container sitting below it. We tried this test today and the pump didn't draw any fuel, however despite the pump turning on, we weren't sure if wasn't already inoperable.
The pumps we have installed are pretty tiny, drawing only 2 amps and from my calculations only pump about 20-22 gallons per hour.
The pumps we have installed are pretty tiny, drawing only 2 amps and from my calculations only pump about 20-22 gallons per hour.
The pump should be self priming, also implys it is okay to run dry for a while. Is it spec'ed for self prime like this one.
Amazon.com: Mr. Gasket 42S Electric Fuel Pump: Automotive
Amazon.com: Mr. Gasket 42S Electric Fuel Pump: Automotive
- Thread starter
- #33
Ok, now I am starting to agree with you and Christo. Once the pump is primed it should be good to go all the way to the bottom of the aux tank.
Just so I am clear.. the definition of "prime" in the above illustration means the tube from the outlet of the aux tank to the input of the pump is full of fuel?
Just so I am clear.. the definition of "prime" in the above illustration means the tube from the outlet of the aux tank to the input of the pump is full of fuel?
Self prime means the pump can be dry and some reasonable distance down the suction line there is fuel. The pump is capable of pumping some amount of air drawing fuel in.
Edit: A primed pump will be full of fuel.
Edit: A primed pump will be full of fuel.
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- Thread starter
- #35
Wayne at Front Runner told me he has been testing pump locations and the only configuration where the pump has failed is when it is mounted 950mm above the tank outlet. Well today, my mechanic and I measured the pump's location on my tank at 880mm above the tank's outlet.
Paul at Equipt tells me his is mounted at the bottom right next to the outlet - although his tank is quite a few years older, not sure why FR would have changed the location.
I have asked Wayne to help be resolve this as it appears to be a design flaw, however my mechanic and I are preparing to fabricate and weld some angle iron around the pump and hoses if we do need to fix it ourselves. Right now we have is temporarily mounted and unprotected in order to test it over the next several weeks.
The only other thing I have suspected and others have suggested is some kind of vacuum/pressure issue. However my mechanic is convinced that if it was a vacuum/pressure issue this would cause problems in the main tank causing fuel delivery issues to the engine.
Paul at Equipt tells me his is mounted at the bottom right next to the outlet - although his tank is quite a few years older, not sure why FR would have changed the location.
I have asked Wayne to help be resolve this as it appears to be a design flaw, however my mechanic and I are preparing to fabricate and weld some angle iron around the pump and hoses if we do need to fix it ourselves. Right now we have is temporarily mounted and unprotected in order to test it over the next several weeks.
The only other thing I have suspected and others have suggested is some kind of vacuum/pressure issue. However my mechanic is convinced that if it was a vacuum/pressure issue this would cause problems in the main tank causing fuel delivery issues to the engine.
Your pump is really mounted 34" above the outlet? That is nearly three feet. I don't think that is possible. Something is not right with the dimensions. Maybe 9.5cm and 8.8cm. More like 4" or 3.4" right?
- Thread starter
- #37
Ok, my metric conversion ability was thrown by the Wayne's email below.
Hi Rob
We have had an experiment running since last week Friday with 3 pumps mounted at 3 different levels on three separate containers. The pumps were fitted at the Bottom of the container, Middle of the container 200mm up and top of the container 400mm up from the bottom and they ran thru the weekend. We turned them off at 7:30 this morning and turned two of them on again at 10:30 and they have been running for the past 4 hours again. The third tank we closed off the top and blocked the breather pipe.
The first two are still working perfectly.
The pump where we caused the vacuum burnt out in less than 2 hours.
I don’t know why this cruiser is causing a vacuum, but in my experience this almost always caused by blocked breathers.
The pump being mounted halfway up does not seem to pose any significant problems. The only time we experienced a problem was where the pump was mounted 950mm above the outlet of a container.
- Thread starter
- #38
Probably everyone is tired of my problems with this darn aux tank and pump. After relocating the pump level with the aux tank outlet, I filled the aux from empty with 25 gallons (it holds 47). I've had consistent problems with fuses blowing when the tank is half full or less.
However, with the pump in it's new location, I didn't have any problems transferring ~20 gallons from the aux to main. I am going to keep testing things, but this appears to be the problem.
However, with the pump in it's new location, I didn't have any problems transferring ~20 gallons from the aux to main. I am going to keep testing things, but this appears to be the problem.
Good to hear that you have had success! Good luck with the continued testing.