Reason for fuel pump failure? July 19, 2014, 02:17:27 pm Yahoo Message Number: 147461My SIL is experiencing all the symptoms of fuel pump failure on his 2002. While exploring on the internet about this issue I saw references to the failure being caused by tank internal delamination.My understanding was the cause is a bad design of the fuel pump.Is there a problem with tank delamination?ThanksTerry R 24TK
Re: Reason for fuel pump failure? Reply #1 – July 19, 2014, 02:51:07 pm Yahoo Message Number: 147463Well on our 2002 MB, there isn't much in the tank to delaminate. I dropped our tank about a year ago to replace the generator fuel line, and while it was down I replaced the fuel pump as a preventative measure (it had over 100k miles). Our tank is basically all steel with some steel baffles welded inside (likely to reduce fuel sloshing). Our tank was remarkably clean inside. I think that it is just a weak part in the fuel system, that causes major problems when it fails. Someone near the tank should be able to hear the pump humming for a little while right after the ignition switch is turned on. A shop should be able to do a fuel pressure check before resorting to dropping the tank. Since the pump is cooled by being immersed in the fuel, it is a good idea not to frequently run with very low fuel levels.HTH, Art
Re: Reason for fuel pump failure? Reply #2 – July 19, 2014, 03:29:41 pm Yahoo Message Number: 147465"Since the pump is cooled by being immersed in the fuel, it is a good idea not to frequently run with very low fuel levels."---- Interesting point, Art; thanks for mentioning that. Another good reason to 'drive on the top half' of the tank!Joan
Re: Reason for fuel pump failure? Reply #3 – July 19, 2014, 08:22:33 pm Yahoo Message Number: 147466"the pump is cooled by being immersed in the fuel"I've heard this before. I'm wondering, though: since the pump is at the top of the tank (right?), for how long is the cooling effect significant?For example, if the pump were two inches deep and the tank were eight inches deep, then once the fuel level dropped below three quarters of a tank there'd be no immersion and hence little or no cooling, barring the occasional splash.Now, I made up the dimensions I just cited as an example. Can anyone tell us what the actual dimensions are, and how far the fuel level has to drop before it no longer cools the pump?Andy BairdTravels with Andy
Re: Reason for fuel pump failure? Reply #4 – July 19, 2014, 09:48:31 pm Yahoo Message Number: 147467"the pump is cooled by being immersed in the fuel"I've heard this before. I'm wondering, though: since the pump is at the top of the tank (right?), for how long is the cooling effect significant? The fuel pump "hanger assembly" mounts through the top of the tank, but the pump itself is near the bottom. The pump is a cylinder maybe 2" in diameter and 4" tall. On the bottom of the pump is a filter "sock" that sits pretty much on the bottom of the tank. From draining my tank, I'd guess that there is still 2-3 gallons in the tank when the gauge read "E".Art
Re: Reason for fuel pump failure? Reply #5 – July 19, 2014, 10:46:34 pm Yahoo Message Number: 147468Thanks, Art. I didn't realize that the pump sat on the bottom. How tall is the tank itself?Andy BairdTravels with Andy
Re: Reason for fuel pump failure? Reply #6 – July 19, 2014, 11:02:35 pm Yahoo Message Number: 147469Thanks, Art. I didn't realize that the pump sat on the bottom. How tall is the tank itself? It's been a while since I had it out, but I'd guess that the tank is 14-18" tall. Here is a link to an image of a typical pump hanger assembly: http://s7d9.scene7.com/is/image/GenuinePartsCompany/NWMDC?$Product=GenuinePartsCompany/786271 Art
Reason for fuel pump failure? Reply #7 – July 20, 2014, 07:47:25 am Yahoo Message Number: 147478the Ford fuel pump failure rate in the past seems to indicate that the Ford pump could use some re-engineering. Does any other manufacturer make a better replacement? Mike"Since the pump is cooled by being immersed in the fuel, it is a good idea not to frequently run with very low fuel levels."----
Re: Reason for fuel pump failure? Reply #8 – July 20, 2014, 09:11:22 am Yahoo Message Number: 147479Mike,I've read that the Ford fuel pump is actually manufactured by Denso (see msg 103459). When I had my code P0191 issues (insufficient pressure at fuel rail) in 2009, I replaced it with a fuel pump from Airtex. That was about 40 K miles ago with no issues since.Alex Rutchka, SE #4 '05 MB
Re: Reason for fuel pump failure? Reply #9 – July 20, 2014, 11:26:58 am Yahoo Message Number: 147481"I'd guess that the tank is 14-18" tall."So if the pump itself is only 4" tall, then it will be fully immersed down to about a quarter tank, yes?Like others here, I prefer not to let my tank go below the halfway mark. But it sounds as if unless one is running on fumes on a regular basis, fuel pump cooling is probably not something to worry about.Andy Baird http://www.andybaird.com/travels
Re: Reason for fuel pump failure? Reply #10 – July 21, 2014, 12:53:30 am Yahoo Message Number: 147508It was inconceivable to me that auto engineers would use a pump that suffered when the tank was low, and that they would not warn their customers about this, so I went looking for information on the subject. The result:I don't think the fuel level has any affect on the cooling of the pump, so there is no longevity bonus from keeping the fuel above 1/4 tank. According to this articlehttp://www.agcoauto.com/content/news/p2_articleid/195and the illustration of the fuel pump assembly, the fuel is pumped through the pump and motor, and it's that flow that cools the assembly. It's not cooled by sitting in a big pond of fuel - if it's running, it's being cooled.Of course, there are a number of good reasons for keeping the fuel level above 1/4 tank. I often do so in hot conditions, because that gives me enough fuel to run the generator and thus the A/C, should we break down or otherwise have an unplanned stop.Eric Greenwell
Re: Reason for fuel pump failure? Reply #11 – July 21, 2014, 12:27:10 pm Yahoo Message Number: 147519Hi all,I always keep at least a half tank in all my vehicles. Living in California, we are constantly waiting for the "Big One" earthquake that is. If the power is cut off for any length of time good luck trying to get gasoline. In fact I always keep a full tank in My Lazy Daze because in case a catastrophe it will become my home. A word to the wise is sufficient.Red Sky
Reason for fuel pump failure Reply #12 – July 19, 2014, 11:06:31 pm Yahoo Message Number: 147470Art,Thank you for the information.It is exactly what I was looking for.ThanksTerry R
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