fuel leak at water sensor - to - filter junction
10-04-2006, 01:10 AM
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fuel leak at water sensor - to - filter junction
My 95 (12v) has sprung a leak!
It leaks a few drops every second while the truck is running.
I even saw it making little bubbles right at the junction between the water sensor and the filter.
I changed the filter and orings (with Mopar brand parts) - no change.
The old oring looks fine also.
No apparent cracks in the water sensor.
The only thing that I can figure is that the pressure relief valve on the the injector pump, that lets excess fuel from the lift pump return to the tank, has become bad and is holding the pressure at the filter so high that it is pushing fuel out.
I checked the return line by taking it off at the tank and watching it flow while the truck was running (and the filter was continuing to leak). I also made sure that the return line in the tank was clear.
Any ideas, thoughts, or comments?
Thanks,
Jeff
It leaks a few drops every second while the truck is running.
I even saw it making little bubbles right at the junction between the water sensor and the filter.
I changed the filter and orings (with Mopar brand parts) - no change.
The old oring looks fine also.
No apparent cracks in the water sensor.
The only thing that I can figure is that the pressure relief valve on the the injector pump, that lets excess fuel from the lift pump return to the tank, has become bad and is holding the pressure at the filter so high that it is pushing fuel out.
I checked the return line by taking it off at the tank and watching it flow while the truck was running (and the filter was continuing to leak). I also made sure that the return line in the tank was clear.
Any ideas, thoughts, or comments?
Thanks,
Jeff
10-04-2006, 09:03 AM
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Wow, your very first post! Welcome! 
Even though you see no cracks, I would just replace the water in fuel sensor. They are only $22 from Geno’s Garage:
http://www.genosgarage.com/prodinfo....31852-S-WIF-DG
The next thing I would do is install a fuel pressure gauge. You need to drill and tap the banjo bolt at the injection pump inlet (search forum for instructions). If the pressure is low, or high, then replace the overflow valve. In fact even if you don’t install the gauge, I would replace the overflow valve anyway, these are very prone to going bad, and it is a five minute job with just one wrench.
Even though you see no cracks, I would just replace the water in fuel sensor. They are only $22 from Geno’s Garage:
http://www.genosgarage.com/prodinfo....31852-S-WIF-DG
The next thing I would do is install a fuel pressure gauge. You need to drill and tap the banjo bolt at the injection pump inlet (search forum for instructions). If the pressure is low, or high, then replace the overflow valve. In fact even if you don’t install the gauge, I would replace the overflow valve anyway, these are very prone to going bad, and it is a five minute job with just one wrench.
10-04-2006, 09:20 AM
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Hey, thanks for the warm welcome! I've searched & read the forums here for a while, but hadn't had a reason to post until now. I am so thankful for this site and the enthusiastic participants like yourself.
Thanks so much for the input! I'll heed your advice and replace both the sensor and the valve.
Have you ever heard of this problem before? I'm a worthy mechanical engineer and I'd swear that the oring, sensor, and filter seat are all good - so that is why I was approaching this as an excess pressure problem.
I should put a pressure gage on it, no problem with doing so (except for my incredible lack of available time). I hadn't considered it yet because I had never found a reference for a MAX pressure, only min.
Just in case anyone cares, I'll post the results (I'll change the valve first and see what happens).
Thanks again for your input - not only is it insightful (I didn't know that the overflow valves were prone to failure), but it is inspiring to know that I've got some somewhere to turn for help.
Thanks so much for the input! I'll heed your advice and replace both the sensor and the valve.
Have you ever heard of this problem before? I'm a worthy mechanical engineer and I'd swear that the oring, sensor, and filter seat are all good - so that is why I was approaching this as an excess pressure problem.
I should put a pressure gage on it, no problem with doing so (except for my incredible lack of available time). I hadn't considered it yet because I had never found a reference for a MAX pressure, only min.
Just in case anyone cares, I'll post the results (I'll change the valve first and see what happens).
Thanks again for your input - not only is it insightful (I didn't know that the overflow valves were prone to failure), but it is inspiring to know that I've got some somewhere to turn for help.
10-04-2006, 10:56 AM
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Here is more info on Overflow valves, there is a reference in there by Infidel (our highly revered expert) about high pressures causing seals to blow:
https://www.dieseltruckresource.com/...ighlight=marty
And some info on fuel pressure:
http://dodgeram.info/tsb/1996/14-07-96.htm
https://www.dieseltruckresource.com/...ighlight=marty
And some info on fuel pressure:
http://dodgeram.info/tsb/1996/14-07-96.htm
10-04-2006, 01:47 PM
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Thanks for the info on where to get an Overflow Valve.
I just got back from the dealer - they wanted $160 + tax. Somehow I knew there would be a less expensive source on this site - and sure enough, when I sat down after getting back from the dealer, your post had what I was looking for - you read my mind.
I'll just have to do without my truck for a few more days...
I just got back from the dealer - they wanted $160 + tax. Somehow I knew there would be a less expensive source on this site - and sure enough, when I sat down after getting back from the dealer, your post had what I was looking for - you read my mind.
I'll just have to do without my truck for a few more days...
10-04-2006, 04:08 PM
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Just want to ask you if you have changed your filter recently? If so did you replace the washer that goes over the threaded pipe that the filter screws onto.I had one of those washers stay on once and me not paying attention put on the new one which doulbed them and i had a leak at the filter. Just another thought for you.
10-05-2006, 01:26 AM
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The fuel leak showed up before I did anything to the filter - I was changing the filter as a result of the leak (since my first assumption was that the oring between the filter and the water sensor was bad).
That square profile ring/washer over the standpipe was quite difficult to remove - I could barely reach it - but I did get it replaced.
Thanks for the input.
* I ordered an Overflow valve from Precision Diesel Injection and Turbo Inc. (Marty Tompkins). It was $40, plus $1 each for washers, and ~$8 for 2 day shipping - not only a great price but I do like the idea of these being made in Germany rather than the Mopar part being made in Brazil.
My sincere thanks to DL1221, infidel, and all the rest of you who contribute!
I am still interested in hearing if anyone else has experienced this problem, or any other problems as a result of the Overflow valve causing too much pressure in the system.
That square profile ring/washer over the standpipe was quite difficult to remove - I could barely reach it - but I did get it replaced.
Thanks for the input.
* I ordered an Overflow valve from Precision Diesel Injection and Turbo Inc. (Marty Tompkins). It was $40, plus $1 each for washers, and ~$8 for 2 day shipping - not only a great price but I do like the idea of these being made in Germany rather than the Mopar part being made in Brazil.
My sincere thanks to DL1221, infidel, and all the rest of you who contribute!
I am still interested in hearing if anyone else has experienced this problem, or any other problems as a result of the Overflow valve causing too much pressure in the system.
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