Ziggy Posted December 11, 2014 Report Share Posted December 11, 2014 Trying to help my brother in law... To begin with, he owns a 2007 Dodge Ram Megacab Shortbed Dually with a 24 valve 5.9 Cummins and a 6 speed manual trans. He had a fuel pump failure a little while ago, and decided to replace the fuel pump with an aftermarket fass fuel pump. He did this with the thought that eventually, he'd like to do some other mods, and he didn't want to replace the fuel pump twice. Since the Fass pump is rated to support 750+ hp, it seemed like sound logic. The truck is otherwise unmodified. A couple of weeks ago, he was driving the truck, heard a loud pop, and what sounded like an air pressure release under his hood. The fuel guage dropped to empty, and the truck stalled. He was able to eventually get the truck started, and went to the gas station to put fuel in it, but the tank wouldn't accept any more than would would fit in the neck. Today, my brother in law and my dad pulled the bed off the truck to get a better look at the fuel tank, and found that the wires running into the fuel sending unit appeared to be blistered, and the check ball (either the anti-siphon ball, or the emergency roll over vent ball, not sure which) was jammed into the neck so hard, it had to be pried out with a screwdriver. So, the question is this; What the hell happened?! I've not seen it, but by what was described to me over the phone, it sounds like the sending unit wires overheated which ignited the fuel vapor in the tank, which caused an explosion just big enough to jamb the anti-siphon/rollover protection ball into the neck, and overpressureize the fuel system causing a pop-off valve under the hood to open. Could all of this be due to jumping to an oversized a/m fuel pump? Brother in law is in Mississippi, I'm in Cincinnati. Haven't had any luck searching the internet for similar issues. What do you know? Quote Link to comment Share on other sites More sharing options...
Jester_ Posted December 11, 2014 Report Share Posted December 11, 2014 Makes sense that the larger pump requires more power than the stock wiring could handle. Quote Link to comment Share on other sites More sharing options...
madcat6183 Posted December 11, 2014 Report Share Posted December 11, 2014 Um no. I've never heard of upgrading any wiring when tossing in a FASS or AirDog system, never. I've looked into them a lot of even read the instructions several times for both units. Neither have upgrading wiring, at least not for a 6.0 or 6.4(Fords). That doesn't mean there wasn't a short that did this however, possibly a chaffed wire, or just a tired wire coating that grounded and sparked. But as for actually upgrading the wiring, never heard of that and I know a lot of people running FASS/AirDogs, never installed one myself, but never heard of this. I'd send the unit to be tested to ensure it's not internal, while that's being done look over the wires and surrounding area for any openings or sharp edges that may have cut the wire or anything of that sort. In theory it makes sense that could happen, but never, ever heard of it. Quote Link to comment Share on other sites More sharing options...
Ziggy Posted December 12, 2014 Author Report Share Posted December 12, 2014 So, the Fass pump he got is the Titanium Series for Cummins 5.9/6.7 24 valve *with in tank Lift Pump*. There is some wiring involved, but it appears to be just what is necessary to power the pump. From what I understand, the blistered wires are on the actual sending unit, not the pump. My question though, is it possible to have an in tank diesel fume explosion that doesn't blow the plastic fuel tank apart? I'm having no luck finding anyone else that has experienced this issue. Quote Link to comment Share on other sites More sharing options...
BadTrainDriver Posted December 12, 2014 Report Share Posted December 12, 2014 I don't have any help with your particular problem, but I can tell you that diesel fumes are not combustible. Quote Link to comment Share on other sites More sharing options...
zx3vfr Posted December 12, 2014 Report Share Posted December 12, 2014 Whaddauknow. A non factory part failing prematurely. This boys and girls is why we don't make toys out of our DD Quote Link to comment Share on other sites More sharing options...
Gixxus Christ! Posted December 12, 2014 Report Share Posted December 12, 2014 I don't have any help with your particular problem, but I can tell you that diesel fumes are not combustible.False. They may not be highly flammable but diesel is very combustible.. Quote Link to comment Share on other sites More sharing options...
ReconRat Posted December 12, 2014 Report Share Posted December 12, 2014 Flash point of diesel is 100F, at 1% to 10% saturation for vapor. Oxygen or other gas catalyst needs to be present. Did one of the internal units overheat. Condition of the wiring is a clue. A typical fuel tank is rated at 30psi, probably designed for 60psi. A known accident burst a diesel fuel tank attempting 125psi. Quote Link to comment Share on other sites More sharing options...
BadTrainDriver Posted December 12, 2014 Report Share Posted December 12, 2014 False. They may not be highly flammable but diesel is very combustible.. I didn't say diesel was combustible, I said diesel fumes aren't. Quote Link to comment Share on other sites More sharing options...
zx3vfr Posted December 12, 2014 Report Share Posted December 12, 2014 Flash point of diesel is 100F, at 1% to 10% saturation for vapor. Oxygen or other gas catalyst needs to be present. Did one of the internal units overheat. Condition of the wiring is a clue. A typical fuel tank is rated at 30psi, probably designed for 60psi. A known accident burst a diesel fuel tank attempting 125psi.dumb statement of the week. diesels don't even use evap systems because it does not redily evaporate. Quote Link to comment Share on other sites More sharing options...
Ziggy Posted December 12, 2014 Author Report Share Posted December 12, 2014 Checked in with my brother in law last night. He said that when he pulled the sending unit out of the truck, the wires on the inside of the tank were completely bare. What he can't say though, is what the condition of the wires was prior to this incident, whatever it is. From looking online, and trying to research this thing, I know that the tank is vented. From what I've been able to find, the vents themselves ( I think there are two of them ) can be issues if they become clogged. I'll check with him and see if he's checked the vents, but it's still a head scratcher. He mentioned he's going to follow up with FASS and a diesel mechanic he knows too. Quote Link to comment Share on other sites More sharing options...
Gixxus Christ! Posted December 13, 2014 Report Share Posted December 13, 2014 I didn't say diesel was combustible, I said diesel fumes aren't.When you light diesel (or any other liquid) it is only the fumes that burn. Liquid phase matter is not combustable. Quote Link to comment Share on other sites More sharing options...
Helmutt Posted December 13, 2014 Report Share Posted December 13, 2014 I'd wager the sending unit itself failed/shorted causing the issue. Probably just coincidence the fuel pump had just been replaced at the time, aftermarket or not. Not sure they share a circuit but likely that they both communicate through the ECM seperately. I used to sell a lot of 5.9 pumps and respective solenoids to farmers, municipalities, and diesel heads, but it's tamed down a lot over the years and rarely see these in our shop anymore. I can help save you guys money on engine components, but we dont deal with anything smaller than class 6 trucks. Quote Link to comment Share on other sites More sharing options...
C-bus Posted December 13, 2014 Report Share Posted December 13, 2014 (edited) .... Edited December 18, 2014 by C-bus Quote Link to comment Share on other sites More sharing options...
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