My second M715 build. What was I thinking?

[jeeper]

Well I may as well admit it as embarrassing as it is. It took me two weeks to figure out I ran out of fuel...

Now in my own defense I had a couple things working against me. First my brand new fuel gauge that worked fine when I installed it quit working and was stuck at 3/4 tank. And secondly I believed I should have had 3/4 of a tank because I had just filled the tank.

I am either remembering wrong or I have a mystery that may never be solved or may take a while to flush out.

First the 3/4 tank belief explanation. I had poured in my 5 gallon jerry can of fuel while I was at home because I started with an empty tank. I proceeded to drive to the gas station about 10 miles away and add 20 gallons of fuel. Assuming at least 10 mpg (my last truck got 16 regularly) I figured I had at least 24 gallons of fuel and probably closer to 26 because the tank wasn't completely empty when I started.

The fuel gauge read over the full mark as I was expecting. I then drove it home.

My son took it to school the following day which is about a 20 mile trip one way. (So far that's about 50 miles if you're keeping track.) That same day I took it to the vet for my dog's appointment. The fuel gauge was a little less than the full mark at that point. I rounded the mileage from Google Maps up to 20 miles total for the vet trip. The next day my son took it to his friends house which is just a bit further than the gas station. I'll call it 11 miles one way. (If my math is still working that should add up to about 92 miles). The next day I got in the truck to go to work and made it about 100 yards when the engine died.
The fuel gauge was reading 3/4 tank.

Even if my truck was getting 10 miles per gallon I should have had half a tank but since my last truck was getting such good mileage I assumed this one was too. By my math 24 gallons and 92 miles travelled equals 3.83 mpg. I don't believe that for a minute,

There is no puddle under the truck and I am not leaving a drip trail behind the truck as I drive. I'm wondering if either myself or my son is forgetting about a trip or two that could account for the missing fuel.

I replaced the fuel sending unit with a new one assuming I had a bad sender. When I installed the new sender the gauge still read 3/4 when the lever was all the way down. It ended up being the gauge itself. When I replaced the gauge it would go down to just under 1/4 tank. That seems to be the best I can get it. Those NAPA universal gauge sets seem to be junk.

Anyway I'm back on the road again. I didn't end up spending a lot of money trying to figure it out but did waste a bunch of time and effort.

I'm now thinking I need to get a working speedometer so I can watch the miles and not be dependant on a fuel gauge that seems unreliable.

[Von]

Well I may as well admit it as embarrassing as it is. It took me two weeks to figure out I ran out of fuel...

... I'm wondering if either myself or my son is forgetting about a trip or two that could account for the missing fuel.

A kid driving a cool truck to school... Yeah I can see a lot of fuel mysteriously disappearing. Especially without a working odometer for Dad to check on... like my Dad used to.

At least it was an easy fix!


I think I went with a Sun gauge and sender. I don't entirely trust them. They haven't given me reason NOT to trust them yet... just habit. Rode a Harley Softail too long to trust fuel gauges...
But as long as I can see the fuel level bouncing around I know I DO have fuel in the tank, even if I don't believe how much it's telling me I have.
No baffles in the M724 tank.

[Mikel]

The fuel gauge read over the full mark as I was expecting. I then drove it home.
...
I replaced the fuel sending unit with a new one assuming I had a bad sender. When I installed the new sender the gauge still read 3/4 when the lever was all the way down. It ended up being the gauge itself. When I replaced the gauge it would go down to just under 1/4 tank. That seems to be the best I can get it. Those NAPA universal gauge sets seem to be junk.

You can add resistors to the signal wire to offset the reading of the gauge towards empty.

[jeeper]

You can add resistors to the signal wire to offset the reading of the gauge towards empty.

Thanks, I did try that but by the time I had enough resistance to get the gauge to go to empty it wouldn't go to full. The variable resistance built into the sweep on the sender is obviously not kept to a very tight quality standard but is ultimately what the problem is.

I may revisit the fuel gauge situation down the road but for now I think I'm running with it. As Von stated, "as long as I can see the fuel level bouncing around I know I DO have fuel in the tank, even if I don't believe how much it's telling me I have".

I'm planning on getting the speedometer repaired/replaced soon. I'll just keep track of how many miles I've gone to get a better feel for what the fuel gauge tells me I have left.

[Mikel]

I'm assuming the sending unit is an adjustable universal type. Maybe the sending unit itself is not set correctly and the arm does not get enough angular travel.

[jeeper]

The sending unit is adjustable and universal but even out of the tank with the arm all the way down the gauge doesn't read empty. With the arm all the way up it does read over full though. The way it is manufactured the sweep itself is visible inside the plastic housing and it is easy to see that the arm cannot use the entire sweep even if it is adjusted. There is no way to adjust it to force the entire sweep to be usable. It seems the pivot point is in the wrong location to allow that to happen. I'm wishing I had taken some pictures to show the poor manufacturing.

I have actually considered using a dc-dc converter to use the stock 24 volt gauge/sender on my 12 volt truck. It seems to be built much better.

[jeeper]

I started looking for a new speedometer today. I found this while searching an auction site. From the description:

Item specifics
Condition:
New: A brand-new, unused, unopened, undamaged item in its original packaging (where packaging is ... Read more
about the condition
Brand:
Aftermarket
Type: Gauge MPN:
Does Not Apply
Country/Region of Manufacture: India UPC:
does not apply

Here is the link to the item:


http://www.ebay.com/itm/WILLYS-JEEP-...wAAOSwstxVTeNx

Anyone have any thoughts on these?

I like the look of the speedometer because it doesn't have the metric numbers on the face and also the gauges appear to be backlit directly (in green?) which will make them easier to see.

The whole set is quite inexpensive. I'm worried I'll be getting what I pay for.

[jeeper]

I ended up buying these.







I'll report about them once they are received and installed.

[jeeper]

If it's not one thing it's another here. This truck continues to taunt me.

On Sunday I thought I'd take my dog to the park so she could swim in the river to cool off and expend some energy. She was ready and patiently waiting for me in the truck when I got there. I got in and turned the ignition on and fired the glow plugs for a few seconds and pressed the starter switch. All I got was a short clicking sound then silence.

The batteries are fully charged. I have voltage at the starters battery cable terminal and when I press the starter switch I have voltage at the starter solenoid.

I pulled the starter and installed my "known good" starter and tried again. This time I only had silence without any clicking first. I pulled it out too.

I took both starters into the garage and connected my big battery charger to each, one at a time, and tested them off the truck. The direct drive starter seemed to work off the truck but the gear drive starter just gave a small spark when I shorted from the starters battery terminal (where the charger + cable was connected) to the solenoid terminal. I tapped on the starter while I tried again and it started spinning and engaging the bendix.

This seems like the classic sign that starter is toast to me. Probably the brushes are shot I'd guess. But the direct drive starter was working fine before I removed it and it's odd that it "seems" to work off the truck but not on the truck.

[Von]

I got no input on the starter problem, but those gauges look great!