Community Forums

chris cross · 08-20-2017, 03:49 PM

My fuel gauge only goes to 1/2 when I fill up. My generator stops when the gauge reads 1/4. Obviously I still have 75 gal. What should be my next step for repair ? Thank you

RVPioneer · 08-20-2017, 09:31 PM

We may need some more info here. The fuel for the generator is supplied by a line that is approximately 1/4 of the way above the bottom of the tank. This prevents the generator from leaving you stranded without fuel. It would seem that the gauge is accurate at the 1/4 reading as this is when the generator will no longer receive fuel.

It is possible that the tank level sensors, or gauge, are faulty when you have a full tank.

Assuming that you add 75 or so gallons when the gauge reads 1/4, are you driving 400 miles or so before the gauge moves off the 1/2 reading?

chris cross · 08-21-2017, 12:47 PM

"It is possible that the tank level sensors, or gauge, are faulty when you have a full tank."

Maybe my post was not clear. I don't add 75 gal. when the gauge reads 1/4, I already have 75 gal because the gauge only goes to 1/2 after a FILL up.
When it gets to 1/4 the gen stops.
I believe your second para is correct. How do I address either of those faults ?
I drive 200 miles = 25 gal.

4x4van · 08-21-2017, 01:10 PM

The gauge has absolutely no bearing on your generator; none. It could read 1/4, 3/4, full, or anything else. Or nothing at all. The pickup tube for the generator only goes partway into the tank rather than all the way to the bottom.

You're assuming that because the gauge only reads 1/2 when you are actually full, that you still have 3/4 tank of fuel when the gauge reads 1/4. But the fact that your generator quits when the gauge reads 1/4 suggests that may not be the case, and the gauge IS correct at its' 1/4 reading. The contact trace for the sending unit could simply be damaged from the 1/2 mark up. It would be very unusual for the pickup to be so short that the generator cuts out at 3/4 of a tank of fuel, unless the pickup tube has been damaged somehow.

In any case, a failing gauge is rare, while a failing sending unit is common. The gauge sending unit is mounted inside the tank, usually as part of the fuel pump assembly. Dropping the tank and pulling that assembly may clarify things. It will also let you see exactly how long the generator pickup tube actually is (I extended mine a bit on a previous coach, but still not all the way to the bottom).

chris cross · 08-21-2017, 01:42 PM

4x4van;
there is no question that when the gauge reads 1/4 I have 75 gal.
I start w/100 gal and the gauge shows 1/2. I drive 200 mi. and the gauge shows 1/4 and the gen stops. I used 25 gal to go from1/2 to 1/4 so I still have 75 gal.
If I read you right then you suggest that it is the sending unit.

wolfe10 · 08-21-2017, 03:30 PM

Quote:

Originally Posted by chris cross

4x4van;
there is no question that when the gauge reads 1/4 I have 75 gal.
I start w/100 gal and the gauge shows 1/2. I drive 200 mi. and the gauge shows 1/4 and the gen stops. I used 25 gal to go from1/2 to 1/4 so I still have 75 gal.
If I read you right then you suggest that it is the sending unit.

Looking at actual fuel level (not gauge reading): 100 gallons minus fuel used to go 200 miles-- say 25 gallons= 75 gallons remaining in tank. The generator pickup is (or should be) WAY below the 75 gallon mark. Guess I would conclude that your generator pickup tube is not deep enough in the tank. Assume you have checked the fuel line at the generator to verify that you have air in the line causing the generator to quit. Assume you have checked for codes on the generator to rule out other causes.

Gauge reading-- start by cleaning connections at the tank. If that doesn't do it, from the gauge or sender unit maker find out ohm readings for various tank levels to see if the gauge is the problem. If not, then replace the tank sender.

4x4van · 08-21-2017, 03:34 PM

Quote:

Originally Posted by chris cross

4x4van;
there is no question that when the gauge reads 1/4 I have 75 gal.
I start w/100 gal and the gauge shows 1/2. I drive 200 mi. and the gauge shows 1/4 and the gen stops. I used 25 gal to go from1/2 to 1/4 so I still have 75 gal.

And it takes ONLY 25 gallons to fill up again; won't take more?

Quote:

Originally Posted by chris cross

If I read you right then you suggest that it is the sending unit.

Yes, but that would not explain why your generator quits when you still have 3/4 of a tank of fuel. You have two different things going on. 1: Your gauge does not read correctly. Likely a problem with the sending unit mounted inside the fuel tank (adjacent to/combined with the fuel pump). 2: Your generator pickup is short. Could be damaged, could have a hole in it partway up, could have had a section break/fall off inside the tank.

The generator is not in any way dependent on the gauge/sending unit other than being next to each other in the tank. The gauge sending unit is a float operated mechanical device inside the tank (adjacent to/combined with the fuel pump) wired to your gauge. The generator pickup tube is nothing more than a tube extending down into the tank; sometimes all metal, sometimes metal with a rubber extension. Drop your tank and pull the fuel pump assembly (sorry, not fun but required). That will tell the story.

LVRVLUVR · 08-21-2017, 08:47 PM

well, here's what I think

so me one monkeyed with it... some all in one pumps , don't fit all the tanks, and some have to be adjusted... so what I think, there was a wrong set up installed that when you use 1/4... it shuts of the gen cause the gen tube is too high..

and it only shows 1/2 when its full, another wrong install...

LVRVLUVR · 08-21-2017, 08:49 PM

Quote:

Originally Posted by 4x4van

And it takes ONLY 25 gallons to fill up again; won't take more?

Yes, but that would not explain why your generator quits when you still have 3/4 of a tank of fuel. You have two different things going on. 1: Your gauge does not read correctly. Likely a problem with the sending unit mounted inside the fuel tank (adjacent to/combined with the fuel pump). 2: Your generator pickup is short. Could be damaged, could have a hole in it partway up, could have had a section break/fall off inside the tank.

The generator is not in any way dependent on the gauge/sending unit other than being next to each other in the tank. The gauge sending unit is a float operated mechanical device inside the tank (adjacent to/combined with the fuel pump) wired to your gauge. The generator pickup tube is nothing more than a tube extending down into the tank; sometimes all metal, sometimes metal with a rubber extension. Drop your tank and pull the fuel pump assembly (sorry, not fun but required). That will tell the story.

a lot of tanks have the gen tube all in one unit...pretty sure all fords are that way also

4x4van · 08-21-2017, 09:15 PM

Quote:

Originally Posted by LVRVLUVR

a lot of tanks have the gen tube all in one unit...pretty sure all fords are that way also

Agreed, but the generator tube, the fuel pump, and the sending unit are all separate components of that "unit". There is one "base plate" on top of the fuel tank. The top of the plate will usually have 3 fuel lines; one from the pump to the engine, one as a return line from the engine, and a third for the generator. It will also have the wiring for the fuel pump and the gauge sending unit. The fuel pump and the float/sending unit is mounted under the base plate, inside the tank. The generator pickup is nothing more than a tube mounted through that base plate extending down near (but not all the way to) the bottom of the tank; it is not actually tied into or dependent on either the sender or the pump.

You (LVRVLUVR) may be correct; a previous owner may have installed an incorrect pump, made for a smaller tank.

LVRVLUVR · 08-22-2017, 08:11 AM

Quote:

Originally Posted by 4x4van

Agreed, but the generator tube, the fuel pump, and the sending unit are all separate components of that "unit". There is one "base plate" on top of the fuel tank. The top of the plate will usually have 3 fuel lines; one from the pump to the engine, one as a return line from the engine, and a third for the generator. It will also have the wiring for the fuel pump and the gauge sending unit. The fuel pump and the float/sending unit is mounted under the base plate, inside the tank. The generator pickup is nothing more than a tube mounted through that base plate extending down near (but not all the way to) the bottom of the tank; it is not actually tied into or dependent on either the sender or the pump.

You (LVRVLUVR) may be correct; a previous owner may have installed an incorrect pump, made for a smaller tank.

that's my thinking,... the easy check would be when it runs out at the gen...try to pump out fuel....how I learn about this was back in the day I would drop the gen tube to make it run down to 1/8 tank because the class c's only had 35 gals of fuel.... so on the way home I would not have enough fuel to run the roof air. most every one I got shut off around 3/8 tank..

then they started making the gen tube as an all in one unit... something about roll over protection and smog evap....so you couldn't just drop the tube...but in this case

4x4van · 08-22-2017, 08:25 AM

Yup, my last class C was the same; gen cut out at about 3/8+ tank. When I had to replace the fuel pump, I extended the gen pick up tube while I had the unit out. It was an "all in one" unit, but I just extended the pick up tube with a piece of rubber fuel line.

DrDaveMA · 08-23-2017, 11:51 PM

Quote:

Originally Posted by chris cross

4x4van;
there is no question that when the gauge reads 1/4 I have 75 gal.
I start w/100 gal and the gauge shows 1/2. I drive 200 mi. and the gauge shows 1/4 and the gen stops. I used 25 gal to go from1/2 to 1/4 so I still have 75 gal.
If I read you right then you suggest that it is the sending unit.

Chris, you are getting a lot of advise from folks that may not be familiar with the Alpine sender, so be careful.

Your sender can be seen and accessed from the driver's side wheel well, turn your wheels all the way to the stop and you will be able to see it. I am assuming this just started, if not let us know. I would check the wires from the sender to be sure you have a good connection to the gauge and the ground. You can also remove the sender and make sure it is operating properly.

Let me know what you find and we can go further if needed.

4x4van · 08-24-2017, 08:47 AM

Quote:

Originally Posted by DrDaveMA

Chris, you are getting a lot of advise from folks that may not be familiar with the Alpine sender, so be careful.

Your sender can be seen and accessed from the driver's side wheel well, turn your wheels all the way to the stop and you will be able to see it. I am assuming this just started, if not let us know. I would check the wires from the sender to be sure you have a good connection to the gauge and the ground. You can also remove the sender and make sure it is operating properly.

Let me know what you find and we can go further if needed.

The fuel tank on an Alpine is in the front?

Didn't realize that we were talking about a diesel pusher; I have no idea how the fuel pump/sending unit/generator pickup is setup/arranged, although I still think that the generator pickup and the incorrrect gauge reading are unrelated.