A Ten-Point Fuel Security Walkaround for Your Apparatus Fleet

We would rather you assessed your fleet honestly than bought hardware on a hunch. If the walkaround below tells you your exposure is low, that is a legitimate answer and you should spend the money elsewhere.

Run it per rig. No tools, nothing removed, nothing installed. A fleet mechanic, a company officer or an apparatus committee member can get through a small fleet in an afternoon.

1. Find Every Opening

Walk both sides. Log every fuel filler and every DEF filler. Symmetrical rigs are not the rule and the second filler is easy to miss when you always fuel from one side.

2. Ask Whether Each Opening Has a Barrier

Three possible answers per opening: nothing at all, a non-locking factory or builder plastic trim door, or something that actually locks. A trim door counts as nothing — it keeps road grime out, not people.

3. Time the Reach

Stand where a stranger would stand and count how many seconds it takes to get a hand on the cap. If it is under five, no observation-based control is going to help you.

4. Map Where the Rig Actually Sits

Not where it is assigned — where it sits. Bay overnight, apron overnight, open lot, on scene for extended periods, staged out of district, at a vendor for service, at public events. Write down which of those apply and roughly how often.

5. Identify the Longest Unattended Window

Out of that list, find the longest single stretch where the rig is stationary and nobody is watching that side of it. That window is your actual exposure. For most apparatus it is not the station overnight — it is an extended incident or an out-of-district staging assignment.

6. Ask What Happens If This Rig Goes Down

Be specific. Who covers? How long does the coverage gap last? Is there a reserve, and is the reserve actually ready? A fuel system repair on a modern diesel is not a same-day job, and this question is the one that decides whether protecting the opening is worth doing at all.

7. Check for Prior Evidence

Pull the maintenance history and ask the crews. Unexplained fuel loss between fills, a fuel filter or injector job nobody could explain, a DEF fault that came out of nowhere, a cap found loose or missing. Nobody logs "fuel theft" — it shows up as an unexplained repair.

8. Look at the DEF Filler Specifically

People protect diesel and skip DEF because DEF is cheap. The risk at the DEF filler is not theft, it is contamination, and a faulted DEF system on an emissions-compliant diesel means derate and eventually a speed limit. Cheapest opening to close; expensive one to leave open.

9. Confirm What Your Chassis Actually Is

Get the chassis, not the apparatus brand. The body builder's name is on the truck but the fuel filler belongs to the chassis. You want the chassis model and year — for example an E-450 cutaway, a Super Duty chassis cab, or a Ram 5500 — because that is what fitment is recorded against. Photograph the filler area straight on and measure the opening and the flat area around it while you are there.

10. Decide Rig by Rig, Not Fleet-Wide

Now you have, per rig, a count of openings, a real exposure window, and a consequence. A frontline engine that stages out of district and a reserve that lives in a locked bay do not deserve the same answer. Rank them and address the worst first.

What to Do With the Results

If the walkaround shows real exposure, look your chassis up in the fitment matrix, which lists every platform we have on file and states plainly whether the fit is verified or still needs measurement. Find My Fit does the same from the chassis side. Order one door per opening — that count came out of step 1.

If your chassis is not listed as verified, that is not a dead end and it is also not a reason for us to guess. Send the photos and measurements from step 9 and we will work from your actual rig.

And if the walkaround says your exposure is genuinely low, we will tell you the same thing: keep your money.