Fuel / Gauge Issues

firebuild · 08-13-2018, 04:27 PM

I have a recurring problem. The fuel gauge in my Lewis/Ford E350 7.3L diesel short bus is super unreliable, and will sometimes just shoot down from above half full to below 1/4 on a minute's notice. This would not be such a big deal if I did not also have an issue where, if the fuel gets too low, I am guaranteed to get air in the line. The bus has two tanks and I try hard to never be at or below 1/4 of a tank on the active one, and try to keep both full at all times, but this not always practical. When the gauge reads 1/4, I pretty much know I can keep driving for a while- I'm not going to run out and sputter to a stop - but what I DON'T know is if I will be able to start up again without priming if I stop to change to the other tank. The bus has to be turned off to make the switch.

Two nights ago, I saw the gauge dip, but I could not immediately get fuel since all the stations that sell diesel near me close early. I had to make a judgement call call whether to turn off the engine to switch tanks (the other one was full), knowing I might not be able to start up again, or to get home and do it, where I'd have the same problem but at least I would be home. I opted for the latter, and here I am, unable to start because of air in the line. Today was the fifth time since I've owned this bus (about 3 months) that I have found myself in this situation.

I can't prime it and turn it over at the same time, so each incident means I have to find someone to push the valve on the fuel filter while I attempt to start it. This isn't always easy, and most people try for a second and then give up, as my new neighbor from across the street just did. I'm now waiting for AAA. This is the third service call I've wasted on this.

Has anyone else had this problem, and is there a solution besides hyper vigilance? I have heard this particular vehicle is prone to air in the line, especially if it's sitting for a while. I haven't driven it in a couple of days.

Rivetboy · 08-13-2018, 04:48 PM

Hi That is a weird situation. You have to turn off the engine, get out of the bus and do what to switch tanks?
I am assuming you are turning a valve from tank 1 to tank 2 is there any wiring on the valve to switch the sending units from 1 to 2?
Assuming that does not cure it, does the gauge act hinky on either 1 or 2?
Then I would suspect a bad fuel instrument or associated wiring.
Does the gauge only act hinky on 1 tank?
I would suspect the sending unit in that tank or assosiated wiring..
As always, jiggle, spray contact cleaner into multi pin connectors and plug and unplug them a few times, loosen and tighten everything you can see and use a super bright flashlight when you are inspecting the system.

firebuild · 08-13-2018, 04:53 PM

Quote:

Originally Posted by Rivetboy

]You have to turn off the engine, get out of the bus and do what to switch tanks?

I don't have to get out, I just have to flip a little metal toggle switch. If I flip it while running, nothing happens. Have to be shut off.

Quote:

Originally Posted by Rivetboy

]Does the gauge only act hinky on 1 tank?

Nope, it's hinky on both.

Quote:

Originally Posted by Rivetboy

]As always, jiggle, spray contact cleaner into multi pin connectors and plug and unplug them a few times, loosen and tighten everything you can see and use a super bright flashlight when you are inspecting the system.

That would be great advice if I had any clue what I'd be looking at when I inspect it LOL. The only reason I know anything is the various troubles I've had.

EastCoastCB · 08-13-2018, 07:03 PM

Depending on how long your filler neck is and how its shaped, you could just do what I do and carry a clean piece of wooden dowel to dip in the tank to see how much is in there.

family wagon · 08-13-2018, 07:05 PM

There are several sub-problems a person could look at here. One "solution" I could suggest is to install a starter pushbutton under the hood. That'll at least make the recovery a one-man job since you could turn the key to run, then push the under-hood starter button with one hand while working the fuel filter valve with the other hand.

That might be the quick hack solution.. but of course fixing the gauge and being able to switch tanks while running would both be better.

Tango · 08-13-2018, 08:12 PM

Are there ANY buses, anywhere with reliable gauges...of any kind?

ol trunt · 08-13-2018, 08:12 PM

In my experience an erratic fuel gauge is usually the result of a bad connection--particularly a bad ground. True, gauges and sender units do sometimes go bad. Get a helper to watch the fuel gauge (key on) and jiggle all the related electrical connections in a systematic fashion. With any luck you will locate your problem.

I'd offer ideas about the fuel problem but I'd need more info on the tanks and switching valve. Was the bus factory equipped with two tanks? Is there both a pusher pump in or at the tank(s) as well as a pump close to the injectors? Is the fuel system of the recirculating type etc? How is the switch from one tank's sender to the other accomplished?

It would seem unusual to me that the switch over must be done with the ignition off. It would seem that such an arrangement could lead to serious events on the road. Jack

firebuild · 08-13-2018, 08:15 PM

Quote:

Originally Posted by ol trunt

It would seem unusual to me that the switch over must be done with the ignition off. It would seem that such an arrangement could lead to serious events on the road. Jack

Hmmm.... Maybe I am 100% wrong. I just know that when I attempted to switch in motion, the gauge did not move. I assumed that meant the switch didn't happen. I'll be honest, I don't know anything about how this is set up. it came this way.

BlackJohn · 08-13-2018, 08:16 PM

When you get this thing running, fill both tanks.
Get a book to track how many hours the engine runs on Tank 1. Every time you shut down record the hours and minutes she ran, with an eye on the guages and note their readings too.
I think a pattern needs to be established on useage to determing guage accuracy.
Mileage travelled is different than runtime useage but gives comparisons as well.

John

ol trunt · 08-13-2018, 08:17 PM

Time for a field trip in and under your bus.

Good luck!

Brad_SwiftFur · 08-13-2018, 08:55 PM

Quote:

Originally Posted by firebuild

Hmmm.... Maybe I am 100% wrong. I just know that when I attempted to switch in motion, the gauge did not move. I assumed that meant the switch didn't happen. I'll be honest, I don't know anything about how this is set up. it came this way.

It may be helpful to point out that sometimes fuel gauges do *NOT* move to a new reading right away; this is done intentionally to help avoid erratic readings when the fuel is sloshing about inside the tank. However, the gauge moves to the "correct" reading upon startup, as there is always the possibility the vehicle has been fueled while shut off.

Next time you switch from a low tank to a full one, give the gauge a few minutes to adjust to a new reading. I'm betting it'll switch on the fly as most of these systems are supposed to.

firebuild · 08-13-2018, 09:04 PM

Quote:

Originally Posted by BlackJohn

When you get this thing running, fill both tanks.
Get a book to track how many hours the engine runs on Tank 1. Every time you shut down record the hours and minutes she ran, with an eye on the guages and note their readings too.
I think a pattern needs to be established on useage to determing guage accuracy.
Mileage travelled is different than runtime useage but gives comparisons as well.

John

That's what I'll do for sure. On the drive from California, I just got in the habit of attempting to fill both every time I saw a station, even if it ended up to jsut be a top off. I had planned to start tracking things now that I'm staying local and not carrying a massive amount of cargo for hundreds of miles a day, but of course, like with most things, I am a day late and a dollar short.

firebuild · 08-13-2018, 09:13 PM

Quote:

Originally Posted by Brad_SwiftFur

It may be helpful to point out that sometimes fuel gauges do *NOT* move to a new reading right away; this is done intentionally to help avoid erratic readings when the fuel is sloshing about inside the tank. However, the gauge moves to the "correct" reading upon startup, as there is always the possibility the vehicle has been fueled while shut off.

Next time you switch from a low tank to a full one, give the gauge a few minutes to adjust to a new reading. I'm betting it'll switch on the fly as most of these systems are supposed to.

OK, thank you. I'm just learning as I go here. It would have saved me a LOT of trouble had I known that's how it's supposed to work, but of course it never occurred to me to ask you all.

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