Why Topping Off won't kill your truck

[RobertD]

What will be hurt by overfilling. Looking at the OP's diagram it is number 8: fuel tank pressure control [Valve] during operation. They are generally not designed for liquids and will not last long if they see liquids often.

On previous cars I thought the same as the OP that it wont harm anything to overfill. I thought the first one replaced under warranty was a fluke but the second one that I paid $400 to the dealer to replace got my attention.

I may be a slow to change my ways but eventually I get there. I now stop at the first click.

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[ndmiller]

These days I put in the gas nozzle and go into QT for a $.50-$.79 ice cream cone. Come out remove nozzle and leave without another thought.

I haven't sat with my car for 15-20 years while it filled up, always did something else while it was happening.

Waiting around to put another splash of fuel to add more range means nothing as I'm not a traveling salesman and fill up once every 2-3 weeks.

 

[EffNo50]

On the diagram eight and nine are the potential problems not five. Five is not a problem on any vehicle I have seen.

Ford in the instruction manual says not to go past one click. I will go with what Ford says on this.

5 is the problem for those vehicles that repeatedly click off or only allow slow filling if 5 is too small or restrictive. Not a problem related to the charcoal canister, but a problem filling the vehicle. It allows the fuel to flow down the main fill hose by allowing the air/vapors to flow up the vent hose to the filler neck instead up bubbling back up to the filler neck.

 

[North Coast Joe]

Remind me not to fill my vehicle next to the Maverick of the originator of this post. I too will fill on the side of caution.
BTW. Since I don't drive much, filling up more often does not allow for the absorption of water vapor that begins in about two to three weeks after gas is filled.
I think the pump may have shut off early on the last fill up, as My Miles to Empty was lower than usual. But, again, it will still last me two-three weeks

 

[The Real Maverick]

I trust the engineers more than I do whoever writes the Ford user manuals. Sometimes instructions and warnings are very vague and may list things that don't apply to all models of vehicles. But It doesn't always tell you that.

Exactly.
100%

 

[The Real Maverick]

Remind me not to fill my vehicle next to the Maverick of the originator of this post. I too will fill on the side of caution.
BTW. Since I don't drive much, filling up more often does not allow for the absorption of water vapor that begins in about two to three weeks after gas is filled.
I think the pump may have shut off early on the last fill up, as My Miles to Empty was lower than usual. But, again, it will still last me two-three weeks

I have not told anyone what they should do. I'm no preacher. But there are a lot of "religious" (dare I say "superstitious") folks on this site.

Can you tell me how water gets into a sealed air tight container about 2 to 3 weeks after filling???

Seems to me, opening the cap on that container more frequently than really needed provides the opportunities for water to get in.

 

[The Real Maverick]

What will be hurt by overfilling. Looking at the OP's diagram it is number 8: fuel tank pressure control [Valve] during operation. They are generally not designed for liquids and will not last long if they see liquids often.

On previous cars I thought the same as the OP that it wont harm anything to overfill. I thought the first one replaced under warranty was a fluke but the second one that I paid $400 to the dealer to replace got my attention.

I may be a slow to change my ways but eventually I get there. I now stop at the first click.

But have you tried it?
The hybrids don't allow over-fills.

A second click or even a third does not constitute an "over-fill". It really doesn't.
It makes sure your pump stop was not premature. That's it.

There was a big hoopla in the Toyota forums a couple of years back. In order to get the advertised fuel volume and advertised range you had to do this.

i'm providing information.
Not giving advice.

 

[TheSEARCH]

Pretty clear,, First click your done. Ford says this. Professionals in the industry say this.

Who says other wise. People on the street with NO expertise at all. I did it my car was fine BS.

 

[Maverick2022XL]

Assuming the fuel system is engineered so that when you do top off the fuel you are not actually overfilling the system then it won't be an issue period. If it is not it will potentially cause issues with excess fuel in the air intake manifold for starters which in turn will affect the ECU ability to maintain the programmed gas/air ratios. The charcoal canister in this portion of the system may fail outright since it is meant to filter gas vapors and not fuel. There are other issues but this is the main one you'll experience. Reality though is if you do manage to top off the gas to the point you cause excess to flow into areas it shouldn't you should get some dtc codes right way like a P0456 or P0441. They should also reset once the excess fuel is purged from the system.

Bottom line if Ford's engineers did their job they idiot proofed this so you can't actually do it without willfully modifying the fuel system.

 

[Peter Lukasch]

Lots of valid points, what I haven't seen explained is the reason to "top off". You're certainly not saving a penny by doing this. Can someone rationalize the reason for this, and why there seem to be so many opinions on this practice?

 

[Glen Baker LLC]

Lots of valid points, what I haven't seen explained is the reason to "top off". You're certainly not saving a penny by doing this. Can someone rationalize the reason for this, and why there seem to be so many opinions on this practice?

600-800 mile clubbers???

 

[The Real Maverick]

Assuming the fuel system is engineered so that when you do top off the fuel you are not actually overfilling the system then it won't be an issue period.

Bottom line if Ford's engineers did their job they idiot proofed this so you can't actually do it without willfully modifying the fuel system.

Thank you for your clear, concise, well said post.

I agree 100% and provided evidence in post #1.

Some people will look at satellite photos and conclude the earth is flat. Most won't.

 

[OleFordGuy]

What will be hurt by overfilling. Looking at the OP's diagram it is number 8: fuel tank pressure control [Valve] during operation. They are generally not designed for liquids and will not last long if they see liquids often.

On previous cars I thought the same as the OP that it wont harm anything to overfill. I thought the first one replaced under warranty was a fluke but the second one that I paid $400 to the dealer to replace got my attention.

I may be a slow to change my ways but eventually I get there. I now stop at the first click.

Yep, sorry you had to learn the hard way. $400.00 is sure not pocket change.

 

[2lbgill]

Why "topping off" is OK as long as you don't spill and pollute.

(And why your car care nut and Uncle Joey have unfounded worries about the "carbon filter canister".)

I put "topping off" in quotes because it's really not possible to, even if you wanted to. So everyone can relax a bit if they want.

This thread is not meant to be a debate and I'm not telling anyone what they should or should not do.

This is information. Information that shows the risks of the past likely no longer exist today.

That said, in the hybrid with capless filler tube, I find it fills fully, reliably, repeatedly with just three clicks. No need to go beyond that.

Here is the fuel system diagram from Ford.

1: fuel fill tube
2: fuel module
3: fuel level sensor
4: fuel tank
5: fuel vapor return line
(5 is what people worry about needlessly)
6: fuel pressure sensor
7: refueling vent valve that opens when you push the refuel open door button
8: fuel tank pressure control during operation
9: carbon canister
10: vent valve
11: vent to atmosphere
12: vent to engine
13: recirculation valve
14: engine intake manifold

The particular technique different individuals use to refuel their trucks should have no effect on the much worried about "carbon canister".

Hope that helps some of you sleep peacefully. How that canister got ruined in a 1998 vehicle bears no resemblance to the hybrid Maverick of today

Two many variables to support any conclusion on anything. Wishful thinking.

 

[Tom 71 Maverick 24]

A couple of notes
- don't attribute to Ford's engineers what is probably pushed by Ford's lawyers.
- Define "overfill". Where is the line beyond which fuel shall not sit?
- How close to "full" is a tank when the pump shuts off. Some nozzles are more sensitive than others. Are those things even calibrated?
- Faster pumping does tend to shut off a little earlier due to splashing and bubbling of the fuel in the filler neck during the filling process. This was highly evident in my old Dodge truck, where I had to fill at a slow speed or risk premature shutoff (very premature, like less than 1/2 a tank).
- Most of the cautionary notes in the manual are Ford's CYA notes, with tidbits of actual important stuff squeezed in here and there. Just like with all products these days.
- Don't equate a credential, such as an engineering license or degree, with a superior level of knowledge. While most engineers are very smart and good at what they do, the credentialization process occasionally gives the certification to someone that is not really that good at what they do (and yes, I've seen it in my profession from time to time).

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