Diesel can show up on a 6.7L Power Stroke from a lot of places: the engine-mounted fuel filter, the injector return system, lines, fittings, injectors. But S&S identified two particular leak points that have something in common. They’re both plastic.

The factory engine-mounted fuel filter housing is plastic. So is the fitting that returns fuel from the injectors. S&S built the 6.7L Power Stroke Fuel Leak Prevention Kit around exactly those two parts, replacing both with aluminum without giving up any filtration.

Why the Fuel Filter Housing Cracks

Plastic is a reasonable choice for a fuel filter housing. It doesn’t corrode, and Ford’s filtration itself is good. The issue isn’t the filter, it’s the material holding it.

That housing sits on top of a hot engine and goes through a heat cycle every time you drive the truck. Over time, repeated heat cycles can degrade the plastic’s strength and the housing can crack.

You’ll usually smell it before you see it. Owners describe catching diesel while driving, then finding fuel pooled on top of the engine, then finding a hairline crack or a pinhole up around the filter once they go looking. Some don’t find it until a lot of fuel has already gone somewhere it shouldn’t.

A diesel smell with no check engine light and no fuel pressure code is still worth chasing down. The truck won’t necessarily tell you.

The Injector Return Fitting

Same story, different part. The fitting that carries return fuel off the injectors is also plastic, which gives the truck a second place to weep or crack.

That said, don’t diagnose it from a puddle. Fuel in the valley can come from the return fitting, the injector connections, the lines, or the filter housing above it, and fuel travels. Where it drips is not where it started.

Find the actual source before you order parts. This is a common-rail system, and throwing components at a leak is an expensive way to guess.

Diesel in the Valley

Fuel collecting around the top of the engine is a common way this problem announces itself, and it’s also the most misleading.

The usual suspects are the upper filter housing, the injector return lines and fitting, and the injector connections themselves. Work top down, clean everything off, run the truck, and watch where the wet spot comes back first. That tells you more than staring at the finished puddle.

How Bad Is It?

Bad enough that S&S built a product around it.

The engine-mounted filter sits near the inboard exhaust. Fuel that escapes a cracked housing has a short trip to a hot surface, and that’s not a fuel loss problem anymore, that’s a fire. This is the actual reason the kit exists.

One safety rule regardless of where the leak is: never run your hand along a line looking for it. High-pressure diesel can escape through a hole you can’t see as a stream fine enough to go through skin. Use cardboard or paper, not fingers.

If the truck is actively spraying or dumping fuel, stop driving it until you know where it’s coming from.

What the Fuel Leak Prevention Kit Actually Does

Two parts, two leak points.

The plastic engine-mounted filter housing is replaced with a billet aluminum one. The plastic injector return fitting is replaced with an aluminum fitting with a hose barb and an easy-release quick connect. Fixing one and leaving the other in place doesn’t make much sense, so the fitting comes standard with every kit.

The part worth understanding is what S&S did with the filter. Rather than fitting an aluminum housing around the OE filter cup, they dropped the cup entirely and went to a two-post mount, which makes room for a bigger filter. The result holds the factory filtration spec at 4-micron absolute at 99% efficiency, and roughly doubles the dirt holding capacity, 23 grams against the OE’s 12.

That matters because the easy version of this product would have traded filtration for durability. Fixing a leak by making the truck’s fuel dirtier is not a fix. The fittings are pre-installed with O-ring sealing joints rated to 2,000 psi, and the mounting holes take an 8mm Allen so filter changes aren’t a fight.

The kit starts at $300. There’s also a Fuel Leak Prevention Kit Plus that bundles in a chassis-mounted replacement filter, $350 or $367 depending on the application, so both filters in the system get refreshed at the same time. On a two-filter truck, replacing one and ignoring the other is half a job.

Fitment

The LPK covers 2011 through 2026 Ford F-250 through F-750 trucks with the 6.7L Power Stroke. It’s a SEMA Category 4 replacement part and it’s made in the USA.

It also plays nicely with the rest of the fuel system. Stock truck, Disaster Prevention Kit, DCR conversion, it works with any of them, because it’s addressing a different problem than either of those products. The DPK contains CP4 debris. The DCR removes the CP4. The LPK keeps fuel inside the fuel system.

If Your Truck Smells Like Diesel

Start by finding where the fuel first shows up, not where it lands.

Check the engine-mounted filter housing and the injector return components early, since those are the two plastic parts most likely to have given up. But don’t stop there just because they’re the usual answer. Lines, fittings, injectors, and high-pressure components all leak too, and a diesel smell by itself doesn’t name a part.

If it does turn out to be the filter housing or the return fitting, the LPK is the version of that repair where you don’t put another plastic part in the same spot and wait for the same heat cycles to do the same thing again.

Frequently Asked Questions

Can the 6.7L Power Stroke upper fuel filter housing crack? 

Yes. The housing is plastic, and repeated heat cycles degrade plastic over time. S&S identifies it as a real leak point on these trucks and built the LPK to replace it with billet aluminum.

Can a fuel leak happen without a warning light? 

Yes. A physical leak doesn’t guarantee a code or a warning. Fuel smell, wet spots, or diesel collecting on top of the engine are worth investigating on their own.

Does the LPK replace both plastic leak points? 

Yes. Every kit includes the billet aluminum filter housing and the aluminum injector return fitting.

Does the LPK reduce filtration compared to the factory filter? 

No. It holds the factory spec of 4-micron absolute at 99% efficiency and carries nearly double the dirt holding capacity, 23 grams versus 12.

Does it work with a DPK or a DCR conversion? 

Yes. The LPK works with a stock fuel system, the 6.7L Disaster Prevention Kit, or the DCR Pump Conversion.