Fuel Filter Prob AGAIN

[almondfarmer]

'02 stock -- I replace the fuel filters regularly. Now (at 125000miles) the truck stalls irregularly, i.e. no pattern other than when it's HOT. Yesterday, the outside temperature was around 100. The engine temperature showed normal. I had stopped at a store for about 20 min and started out of the parking lot when it stalled. After about 30 minutes, I primed the filter and it re-started. Oddly, this has only happened twice in the last 3 months. I suppose there is a fuel system leak.

Where should I start (other than the obvious filter change)? Where should I finish? I don't have any fuel "leaking" anywhere, so I suppose that it's an "air in" rather than "fuel out".

What do you think?

[DmaxMaverick]

If you are using the new(er) plastic can filters, they seem to leak more often if overtightened. They should only be tightened by hand. While there could be other reasons, almost all fuel/air leaks are at the filter: either the upper or lower O-ring, or a cracked WIF sensor (less common). With no more than what you've seen, this is no reason to not trust the truck. If it stalls, pump it up and move on. Check the common issues in the meanwhile. The system has no fuel lift pump between the tank and HP pump (suction-only system), so an external leak is highly unlikely.

[almondfarmer]

Thanks!!! I'll re-do the fuel filter.

Any reason to suspect the fuel filter housing? Should I replace that just to be sure or is there a system to see if there is a crack or...?

[DmaxMaverick]

Don't replace the filter assy, just yet. Dealers replace them often, after they've thrown up their hands. It's a part to throw at the problem, and it isn't their wallet. Most often, the new filter assy "fixes" the problem. Problem is, the real problem was fixed by the R/R of the assy and installation of the new filter element. Sometimes, reseating hoses and clamps is all that is needed. Test it first, thoroughly. If you have a significant fuel leak, enough to cause frequent stalling, you can pressurize the full system from the tank to the pump. Buy a new fuel filler cap (make sure it is the correct "Diesel fuel only" cap, they aren't expensive anywhere but the dealer). Stant brand is made by the same as OEM. Set it aside, for now. Take your old cap and fit a tire valve onto it (disassemble it, drill it, whatever works). Install it onto the filler, and apply no more than 5 PSI of shop air (regulated!!). This is best done with a full tank (less air volume). Any leak enough to cause frequent stalling should show itself very quickly. You'll see/hear escaping air, and/or a liquid leak. Inspect the entire fuel plumbing carefully. Address the leak, then install the new cap (save your new "tool" for later use).

[Kennedy]

Put the system under pressure with a lift pump and you'll be doing the fuel system a great favor and should stop any air issues. You may even find a seep or leak.

[almondfarmer]

After a bit of hot weather, looks like I have to replace the fuel filter housing. After running in hot weather, my 02 wouldn't start. I primed the line and it started right up. I noticed a little fuel on the top of the housing. As I've read here, that is a classic sign of a cracked housing...here goes $900...

[Kennedy]

PUT A LIFT PUMP ON IT

Once under sustained supply pressure you will be able to verify if it is leaking.


I have yet to see a verified case of a cracked housing. Simply a matter of replacing a couple of orings.


And of course if you are using a plastic filter swap to a metal one and quit using that sub standard junk.

[WhiteTruck]

The only "cracked" housing I have even seen was on a lifted truck with the U shaped upper shock mount coming loose and tipping into the filter. That was just plain busted. As Kennedy mentions, the leaks are typically the hand pump seals or filter seals.

[almondfarmer]

Changed the filter housing and the problem is fixed. It might have been the seals, but I wasn't able to change those.

[Kennedy]

Not much to go wrong on the filter housing. About $10 worth of orings. Usually it's the fuel heater oring that leaks. Add a lift pump and they seldom leak when under pressure.