pressurized fuel tank, leaking out the top of the module?? - Dodge Diesel

horselady · 07-04-2012, 01:53 PM

I found a puddle of fuel under my truck, looks at though it appears to be leaking out of the top of the tank. Current fuel level is less than 1/4. My initial idea was the clip on the return line was broken and that fuel was leaking down while the truck was sitting. I have twice started it right up, so the supply line is not leaking. However we started it today to locate the source of the leak and looks as if it is coming from the vent side of the module. The top of the module has a puddle of fuel on it. before we started the truck, I removed the cap and the tank was pressurized I think more than normal, but I wouldn't swear to it. We are going to clean off the top of the tank and dry it to try to pinpoint the source of the leak. A friend on mine is telling me he clamped a vacuum cap around the vent after his started leaking after he installed a 60 gallon aux tank. Just wondering if this is a common issue, the part that worries me the most is wondering why the tank seems to be pressurized

johnh · 07-04-2012, 03:27 PM

the tank should NOT be pressurized! the vent is probably plugged

dkenny · 07-07-2012, 01:20 PM

have you checked the fuel cap?
might not be venting..but that might be only part of the problem?
could the fuel lines that come out of the tank be leaking too?

-dkenny

tspooner3 · 07-08-2012, 11:48 AM

I had to replace my fuel pickup and lines due to corrosion in my 99. Return line could have a pinhole in it allowing fuel to leak, puddle and run down side of tank

SIXSLUG · 07-08-2012, 12:59 PM

I'd check the fuel cap to make sure it is working correctly.

Simple stuff first....

KATOOM · 07-08-2012, 08:49 PM

Potentially two things going on here. One is that your fuel tank is probably not "pressurized" but actually what you're hearing when removing the fuel cap is a "vacuum". There is nothing to create pressure in the tank but removing fuel will create a vacuum if the fuel module vent isn't working or is caped. I believe the fuel cap isn't vented because the tank is vented. And its not terribly uncommon to hear someone who has a truck where the fuel module vent cap was never removed on the assembly line.

Also, if you look on the fuel module, amongst all the other lines and wires, you'll see there's short rubber line pointing up (about 1.5"-2" tall) thats caped. I'm not sure what this is even for but its prone to cracking and the sloshing fuel will easily escape and cause a leak on top of the tank. If you're not seeing fuel drip while the engine is running then its not related to the fuel supply or return lines.

07-04-2012, 03:27 PM
johnh Registered User Join Date: Nov 2002 Location: lyman, utah Posts: 3,360 My Photo Gallery My Classified Ads	the tank should NOT be pressurized! the vent is probably plugged __________________ 01 3500 ho 2WD;4 inch exhaust bully dog stage 3 inj edge comp(removed hybrid hx 35/40 8/25/04) dyno 419.2 hp 891.8.torque w/stage 2`s on a dyno jet 6/25/03 ,htb2 turbo installed 8/25/04, not a dually any more,conversion done in 04... added home designed propane march 07 (to improve mileage) new vp 44 from industrial injection 3/july/07 181000 miles, removed stage 3 injectors ,reinstalled stage 2 to try to control EGT's better.new head gasket by industrial injection 17 dec 2010

07-07-2012, 01:20 PM
dkenny Registered User Join Date: Jul 2008 Posts: 364 My Photo Gallery My Classified Ads	have you checked the fuel cap? might not be venting..but that might be only part of the problem? could the fuel lines that come out of the tank be leaking too? -dkenny __________________ '99 dodge ram 2500, 4x4, auto. 4" mrbp turbo back, Air Dog 100, fuel pressure, boost and EGT gauges '06 jeep liberty '84 Detroit diesel 8.2L turbo..blue bird school bus->no longer. tranny died(4/11)

07-08-2012, 11:48 AM
tspooner3 Registered User Join Date: Mar 2005 Location: Rhode Island Posts: 19 My Photo Gallery My Classified Ads	I had to replace my fuel pickup and lines due to corrosion in my 99. Return line could have a pinhole in it allowing fuel to leak, puddle and run down side of tank

07-08-2012, 12:59 PM
SIXSLUG Registered User Join Date: May 2006 Location: Pacific NW, B'ham, Kalispell MT Posts: 3,499 My Photo Gallery My Classified Ads	I'd check the fuel cap to make sure it is working correctly. Simple stuff first.... __________________ Kurt 2001.5 2500 QC LB 4WD H.O. 6-SPD SLT Plus 3.54's, Camper/Tow/Plow, A.R.E. Canopy w/ SS Vanguard rack, Southbend clutch and hyd.,TIMBO APPS, BHAF/Heatshield, MBRP 4" TBE, FP Gauge, Femco E-Z Drainplug, DSS, Thuren Trac Bar, 2" leveling kit, P/H Tow Mirrors, PBR, 128K miles. FASS LP "When I was younger I could remember anything, whether it happened or not." Mark Twain Support Our Troops! NRA, MSBL, BYO, GSP, BOLTS, Southpaw, CDC* *Cracked Dash Club

07-08-2012, 08:49 PM
KATOOM Registered User Join Date: Jan 2003 Location: The "real" Northern CA Posts: 2,244 My Photo Gallery My Classified Ads	Potentially two things going on here. One is that your fuel tank is probably not "pressurized" but actually what you're hearing when removing the fuel cap is a "vacuum". There is nothing to create pressure in the tank but removing fuel will create a vacuum if the fuel module vent isn't working or is caped. I believe the fuel cap isn't vented because the tank is vented. And its not terribly uncommon to hear someone who has a truck where the fuel module vent cap was never removed on the assembly line. Also, if you look on the fuel module, amongst all the other lines and wires, you'll see there's short rubber line pointing up (about 1.5"-2" tall) thats caped. I'm not sure what this is even for but its prone to cracking and the sloshing fuel will easily escape and cause a leak on top of the tank. If you're not seeing fuel drip while the engine is running then its not related to the fuel supply or return lines. __________________ '01 5spd. 4x4 Sport shortbed, 285's, EZ, aFe intake, no silencer ring, straight piped, ISSPRO EV pyro/boost and FP all on pillar, Westach Transmission/Differential temp gauge in dash pod, Raptor 100 and Big Line kit to VP, Pac brake, 2 lo kit, Rancho RS9000X's, 2" leveling kit.

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