Small fuel leak ??

[Concrete John]

Ok , 1990 CC 4x4 7.3 (95 eng trans transfer case dash you name it) , just noticed past 2 days small leak, dripping from starter/inspection flange, appears to be from lift pump just below intake , but very hard to see exactely where.High pressure side i'm thinking only because it's a small drip every 2-3 minutes idling. i can only see what looks like a large nut /regulator maybe ? i dunno, was proud to brag about" not a leak on the ole mule" , but i can't now , any suggestions would be greatly apprciated. The truck is on the go every day .....lonngg days also i might add ,Concrete season non stop weather permitting.

 

[rammertide07]

Is there a puddle of fuel in the valley?

 

[Concrete John]

Yes, it appears to be a small trail from under the fuel pump , but even with a rag , i cannot seem to find where it originates from. farther towards the front ? it just wicks the entire towel. if you know what i mean .

 

[BJS]

most likely it is the fuel pump dying, there are weep holes that will leak when it is starting to fail. If you get an inspection mirror and hold it just right you may be able to see them dripping but not always. They tend to last around 100k miles

If you have fuel in the valley the possible culprits are the 1)fuel pump 2) corrosion has eaten through the bottom of the fuel bowl 3) drain valve malfunction 4) fuel lines/fitting leaking

I will recommend that you replace the fuel lines in the valley when you replace the fuel pump also. They are a bit brittle after a few years and can be difficult to get to reseal, I replaced mine with fuel injection hose from napa with the special fuel injection hose clamps, the hose is diesel fuel rated.

 

[rammertide07]

Last year I had a fuel leak in the valley. I took it to Ford and they showed me the part that was bad. It was a freeze plug...I think...a little yellow valve. They just replaced that part and still goin good. Thats my only experiences with fuel leaks in the valley.

 

[BJS]

Last year I had a fuel leak in the valley. I took it to Ford and they showed me the part that was bad. It was a freeze plug...I think...a little yellow valve. They just replaced that part and still goin good. Thats my only experiences with fuel leaks in the valley.

your leak was the fuel drain valve for the fuel filter... the OBS Trucks have a different fuel system which puts a mechanical fuel pump in the valley driven by an eccentric on the camshaft. that is the culprit for most of the SD fuel leaks the most common point for the OBS trucks is the fuel pump. The SD trucks filter fuel at high pressure the OBS trucks filter fuel at a much lower pressure.

the fuel flow in an OBS truck goes Tank -> selector valve -> low pressure pump -> fuel filter -> high pressure pump -> heads -> regulator -> tank or that's what I seem to remember, the high & low pressure pumps are incorporated into a single unit which is why you see two piston units on the pump.

 

[Patrick Feeley]

Another common leaker on OBS fuel systems is the Fuel Restriction Sensor. On early PSD's it was on the backside of the fuel bowl near the bottom. On the later ones it is on the fuel pressure regulator block. If that was it, you can plug it with a 1/8 NPT plug just don't overtighten and crack the fuel bowl or regulator block). If your's is an early one (which it may very well be), you'll probably need to remove the fuel bowl to plug it. You can also try tightening the banjo bolt with a 1-1/4" wrench as that can leak as well. Cheers!

 

[Concrete John]

Thanks very much , for the useful information,hopefully sooner rather later i will apply these suggestions , i suspect the fuel pump (is on its way out as a few times today while @ a light my idle was "hunting" slightly, which i'm reading as a sign of low or inconsistant fuel pressure, on that note it seems to accelerate ok , but then again i'm still rather new to the truck , and PSD. However i do have diesel experience , but has been a while since turned wrenches for a living . Again thanks for all the input ( i plan on some mild performance tuning, in the future only mild mods,so it'll be in the family for awhile...fyi)

 

[DaveBen]

Hey Concrete John, fill out your signature with what you drive so we all can see. You can do this by going the the USER CP in the TOP BLUE LINE above and clicking on Edit Signature. This will help us help you.

Dave

 

[Concrete John]

Thanks ...Done Dave ben