"HOT" Facet Fuel Pump?

[hanleyclifford]

Jerry - The drift of my comment is that on the truck at 12.48v the thing didn't go over 108 degrees. Maybe, just maybe, the pump wants less voltage. Could there be some sort of internal resistor in the pump that is fried? True, I was taught that less volts meant more amps for the same watts and therefore more heat, but could there be some other scenario? Lets get Neil thinking on this one. Sorry about contributing to your delinquency. Hanley

[sastanley]

Oh, I get what you are after hanley...we need a third environment...a battery connected to a charging source, like a battery charger that is pumping 13.x volts to the battery that the pump is connected to, so that we more closely simulate the boat's environment.

[hanleyclifford]

No, what I am suggesting is that maybe we limit the voltage on the BOAT!

[roadnsky]

No, what I am suggesting is that maybe we limit the voltage on the BOAT!

Hanley-
I see where you're going.
Let me get my long-winded novel, er... latest test results posted, then maybe this weekend I can experiment with some voltages...

[roadnsky]

Getting somewhere?

Ok, this will take a while.
So grab a beer and pull up a seat...

I think that Neil may have hit it on the head as to what’s going on
with his theory of the float valve and only really using about 3% of what the Facet is pumping…

“Routing the Facet discharge hose back to the 5 gallon tank doesn't replicate conditions on the boat. There, the Facet is pushing against an often closed float valve increasing the output pressure to the limit of the internal relief valve. Therefore the bench test pump isn't working nearly as hard as the boat pump and it benefits further from the cooling effect of more flow. Assuming our pumps can deliver around 30 gallons/hour and we use 3/4 gallon/hour, we're pumping fuel less than 3% of the time.

Maybe provide a way to close off the discharge hose on the bench test apparatus.

Ooh, another thought: with the discharge hose closed, is the output pressure the same on both pumps? And how does it compare to the specs?”

So, I did basically 2 more tests.
One on the boat, duplicating the original bench test.
(5-Gal direct to the Facet with output direct back to the 5-Gal)

The second test was back on the bench trying to mock-up the scenario of the
carb and float valve doing their thing and effectively “blocking” fuel flow about 70% of the time.

More testing results…

BOAT TEST:
Running from the 5-Gal to the Facet and straight back into the 5-Gal…
Basically doing the same as the earlier bench test to make sure the pump doesn’t heat up under the “Boat Conditions” while simply pumping fuel thru it.
After 15 minutes of running, the pump heated up from 94° to 103°
So, same results as the bench.

I did do another “sub” test to try and visually see Neil’s theory of fuel flow from the Facet to the carb.
I used a new hose and put a CLEAR filter in-line where the polish filter would normally be. (between pump and carb)
Running at 1200RPM, you can see the filter fill up then drain out and stay almost empty for about a minute, then fill up and repeat the process again.
Did this for 15 minutes. Pump got hot. Went up to 124°

NOTE HERE:
Don and I have been discussing what would happen if the power source was the battery instead of the coil's + term.
So, also for these tests I ran a wire from the pump thru a 2-position toggle switch to my battery buss-bar.

BENCH TEST:
This time I had the pressure gauge in-line.
I couldn’t find a Shut Off Valve that would work yesterday without ordering something,
so I used a bolt that did a pretty close simulation to what the float valve is doing.
Here are some numbers:
Air Temp: 94°
Pump Temp @ Start: 91°

BEFORE output hose blocked (free flow):
VOLTS @ Pump: 12.62
AMPS: 2.21
PSI: 0-.5 (couldn’t get a reading. No pressure with free flow)
TEMP: 2 min @ 94° / 5 min @ 97°

AFTER output hose blocked (“float valve” in):
VOLTS @ Pump: 12.62
AMPS: 2.25 – 2.12
PSI: 2-2.2 (immediately rose to 2 then slowly rose to 2.2 and stayed there)
TEMP: 2 min @ 102° / 4 min @ 105° / 6 min @ 107° / 8 min @ 109° / 10 min @ 111°

I think we see a trend. A 20° temp rise in 10 minutes is just what has been going on at the boat.
As Neil surmised, with the “blockage” the float valve is doing and the pump suspending fuel inside itself, we get more heat.
This also seems to be supported by my first testing back on July 4th reported in POST #30:

“Pump is putting out what it should be.
Varies between 2 & 3 PSI.
At cold start, the temp reading was 95° at the pump.
(Air temp was 104°. But remember, it's a DRY heat!)
After 10 minutes of idle, the pump temp was 110°
After about 20 minutes at idle... 130°
Cruising at 1600 RPM... 124° (Temp stays there no matter length of time)
Cruising at 1800 RPM... 118° (Temp stays there no matter length of time)

Interesting that the temp went down at a higher rpm, likely due to more fuel flow thru the pump, so a little better cooling?”

The temps went down as fuel demand went up. More flow. Less blockage by the float valve.
So, where are we?

The vacuum gauge finally arrived.
I’m gonna do some testing with that and maybe play with Hanley's lower voltage idea over the weekend.

But, for now, I’m going sailing!

[Administrator]

As to temperature somehow being associated with how much fuel the pump is or is not moving through the system, what is different or unique about your installation that would explain why your pump get hot and other folks' pumps don't?

Bill

[hanleyclifford]

Jerry - That was an exciting post and has got me thinking again. It sounds like Neil is on the right track. I do have a question. If the pump has an internal relief valve, to where does it relieve? How can the pump relieve pressure if it is an enclosed structure with only one way in and one way out? If it has an internal cavity to accept excess pressure, what happens when it is full? On automotive systems a return line to the tank is provided. Can some one explain to me how a closed system can be a pressure relief system?

[roadnsky]

As to temperature somehow being associated with how much fuel the pump is or is not moving through the system, what is different or unique about your installation that would explain why your pump get hot and other folks' pumps don't?

Bill

Well, that's certainly the money question.
Obviously with all the other pumps out there and most of them mounted on the engine, you gotta wonder if I'm the only one?
The only obvious variable with my situation vs many is the higher air temps (100+) but I'm soooo wide open to any other ideas...?
OR, see any flaws in the testing??

[roadnsky]

Jerry - That was an exciting post and has got me thinking again. It sounds like Neil is on the right track. I do have a question. If the pump has an internal relief valve, to where does it relieve? How can the pump relieve pressure if it is an enclosed structure with only one way in and one way out? If it has an internal cavity to accept excess pressure, what happens when it is full? On automotive systems a return line to the tank is provided. Can some one explain to me how a closed system can be a pressure relief system?

Is Dave Neptune still cruising the island?

[ndutton]

As to temperature somehow being associated with how much fuel the pump is or is not moving through the system, what is different or unique about your installation that would explain why your pump get hot and other folks' pumps don't?l

Don't know for sure but here are a couple of thoughts:

Is the pump actually heating up unusually? I've never checked underway, for all I know mine could be just as hot. I'll be sure to pay more attention now.

Jerry's ambient temp is way higher than most, being in the Nevada desert. He keeps saying it's a dry heat but so is Hell and hot is hot.

I'm waiting to hear the results of his final testing but it looks like this is the way it is, hot. The choice will have to be made what, if anything, is to be done. So far we don't seem to be able to prevent it so we're left with dissipating it. Back in post #36 of this thread we started thinking about this very situation.

[Administrator]

It's a little late to be asking this, but have we tested and abandoned the notion that this is simply a bad pump?

Bill

[rigspelt]

why your pump get hot and other folks' pumps don't?

I am still not sure that we have established what abnormally "hot" means. Facet apparently says the operating temperature window upper limit is 180, and we all run our engines no more than 180. If an engine is running with coolant measuring 170, for example, then it seems reasonable to me that a fuel pump bolted to the engine would feel hot to the touch. Ours does, for example.

[roadnsky]

Don't know for sure but here are a couple of thoughts:

Is the pump actually heating up unusually? I've never checked underway, for all I know mine could be just as hot. I'll be sure to pay more attention now.

Jerry's ambient temp is way higher than most, being in the Nevada desert. He keeps saying it's a dry heat but so is Hell and hot is hot.

I'm waiting to hear the results of his final testing but it looks like this is the way it is, hot. The choice will have to be made what, if anything, is to be done. So far we don't seem to be able to prevent it so we're left with dissipating it. Back in post #36 of this thread we started thinking about this very situation.

Neil-
I'm actually shopping for the heat sync solution you suggested earlier right now!

It's a little late to be asking this, but have we tested and abandoned the notion that this is simply a bad pump?

Bill-
Not 'officially' but I have TWO pumps and they're both exhibiting the exact same symptoms.

[hanleyclifford]

I really think we need to stay focused on the issue Neil originally brought up - the test with no downstream blockage yielded the lowest terminal temperature yet when the normal resistance of the carburetor is applied the heat goes way up. We need to draw the right conclusion from these facts. It may be that additional questions need to be answered. Exactly how does the pump deal with excess pressure? Is the pump supposed to shut off when its specified pressure is reached in the downstream line? If that is the case, is it in fact shutting off? On the Carter pump that I use the pump stops working when specified pressure is reached and only cycles to maintain pressure. Is this the case with the Facet pump? These questions can be answered thru appropriate tests.

[ndutton]

When I referred to an internal pressure relief valve, I was speaking generically. There's certainly an internal maximum pressure device in the Facet pump but I'm not privy to the details of how it functions. Common sense tells me it likely bleeds from the outlet chamber to the inlet chamber when the maximum is reached.

I can attest however that the Facet electric pump runs continuously. Kinda supports the chamber bleed theory. How is the fuel pressure regulated on the mechanical pumps? There's no return line to the tank on those either.

I think the low temp bench test with the fuel returning directly to the tank had to do with the cooling effect of the flow. Run 95 degree fuel through a 125 degree pump and it'll cool.