Anyone had a 3rd gen truck fuel leak?

[BigblueC]

Well I'm getting ready for a vacation coming up in a few weeks and out of nowhere my truck starts pouring fuel from somewhere around the pump assembly. It's not an instant pour. No spray as soon as the key cycles or anything. The truck needs to run/drive for a little while to pool fuel around the assembly. The pump seems to run fine. Light tugs on the lines indicate they are securely attached. So before I drop the tank or pull the bed have any of you had to deal with this problem? A google search has brought a mixed bag of "could be" answers.

The truck is a 05' Ram, 1500, 4x4 with a 5.7 and a 36 gallon fuel tank.

 

[Johnny Mac]

I had the notorious "doesn't shut off at gas pump" issue fixed on mine under warranty. After they fixed THAT...the fuel clamps from the pump assembly blew off about a mile down the road. apparently they corrode, and them messing with the pump was enough to render one defective. I'd assume you have a OE "crimp clamp" thats probably corroded, and about ready to give way. its holding the line on the barb...but under pressure, it's probably not enough to hold 60PSI.

 

[BigblueC]

I had the notorious "doesn't shut off at gas pump" issue... After they fixed THAT...the fuel clamps from the pump assembly blew off about a mile down the road. apparently they corrode, and them messing with the pump was enough to render one defective. I'd assume you have a OE "crimp clamp" thats probably corroded, and about ready to give way....

I haven't heard anything about an issue with not shutting off at pump. I had seen others on different forums posting about the locking rings around the pump assembly rusting away, and mine appears to be corroded. How bad I don't know yet. I'll check the ends/crimps. Hopefully it's that simple. How did you go about fixing your lines? Did you replace with OEM stuff or just new rubber and worm gear clamps?

 

[Johnny Mac]

I haven't heard anything about an issue with not shutting off at pump. I had seen others on different forums posting about the locking rings around the pump assembly rusting away, and mine appears to be corroded. How bad I don't know yet. I'll check the ends/crimps. Hopefully it's that simple. How did you go about fixing your lines? Did you replace with OEM stuff or just new rubber and worm gear clamps?

Since i made them come get it where it sat, fill the tank back up, and fix it AGAIN... i assume they just put crimps back on it, but I didn't do it myself, Sorry.

Not that it matters, but the overflowing at pump issue is super common. Jeep's did it too. Had to do with the built in check valve thats physically integrated into the tank. I know my tank is not the 36 gallons you claim however..so maybe bigger tanks never had the issue.

good luck either way!

 

[BigblueC]

Alright my mechanic friends, I could use some knowledge. I used a pressure gauge and there is a steady leak under pressure. I know for sure that the pump works and pumps up to the correct pressure. In my testing I found that the first key cycle jumped pressure straight up to ~30 psi, then started bleeding down immediately. On key cycle #2 the pressure jumped to 58 psi (what is called for), and again immediately started to bleed down. Key cycle #3 and pressure returned to 58 psi, then again instantly started bleeding down. There is no steady pressure retention. One minute mark and it was at 42 psi. Two minute mark - 36 psi. So pressure drops quickly.

I then started it and it maintained 58-60 psi, never fluctuating. But as soon as I killed it, it began bleeding off pressure like above. So to me the pump clearly works.

Now the tank is out of the truck and there are no clearly visible cracks. So how do I determine/test the fuel line coupling at the tank, or how can I test the pump under pressure out of the truck? How can I isolate one or the other here?

 

[70bigblockdodge]

Put 12 volts to pump with the line plugged. You could pull sending unit and pull pump and plug then charge with shop air and squirt with soapy water.

 

[BigblueC]

Thanks for the suggestion. I wish I would have thought about plugging and pressurizing the pump before I pulled the unit and drained the tank. I wound up cleaning the tank and assembly top pretty heavily, which revealed a hairline crack near the outlet nipple. It was invisible until I got the yellowish tint scrubbed off, which revealed the dirty crack. Other sections of the plastic assembly were degraded so I found a MOPAR unit on rockauto. Hopefully this is my 1 and only leak!

 

[70bigblockdodge]

Cool glad you found it.