Pre-Power Stroke Diesel (7.3L IDI & 6.9L)Diesel Topics Only
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This past week I replaced both the fuel tank sending units. The rear unit was a major pain, and the pick up was sitting on the bottom. God was nice to me on the front tank, the entire project took 45 minutes.
For both the front and back tank I yanked out the black plastic filler tube that I guess is to help the fuel tank vent when filling. I was hoping it would make a big difference in filling my rear tank, but no difference at all. I wonder when other folks have done it have they also modified the filler neck? The fuel gets restricted right up top for the first few inches until the crimped that plastic on.
The good news is now my fuel gauges work!!!! And I can run both tanks almost to the bottom!!!
I thought one or two of the folks said they got it to fill faster by taking those hoses off.. I'm going to look at the rear tank filler spout and see about taking out the metal part that is actually restricting the fuel. I'm hoping somebody who has done this can tell me what we're doing wrong?
ive had problems with slow fills also. i found that it was the pump i was using the times before. i used a pump today that i could hold wide open and it filled up fast. i guess some of the pumps are more sensitive than others..?
I am having the fill problems too. I pulled the internal fill hoses, and it did help some. It fills a little bit better too since I chiseled out the hole so I could use a big truck pump station.
But as someone else mentioned, I found the biggest difference is the nozzle the station uses. When I went on my 2000 mile trip, some pumps would fill fast, some wouldn't. After observing this, it seems some of the pump nozzles tend to "stir up" the fuel, causing it foam. The foam fills the entire fill pipe up, and gets caught in the air coming up the fill pipe.
I think the basic cause of all our problems is the air coming up the fill pipe. My next course of action is to investigate the vent lines on the tank. If I can make them breath better somehow, then the air can go that way instead of coming up the fill neck and interfering with filling.
I think you are maybe right about air in the pumps
well i've already checked my vent, muddobbers nost in one, spider in the other one. i thought great, here's the problem,guess what. next fillup didn;t help.so i check vents again,blowed in through hose no problem, and when i quit blowing. air flowed back out no problem, so i don;t think vents are the problem. i have noticed a difference at different pumps,like you said. I say have a beer,doesn't bother me then. we should ask some guys with newer trucks if they have the problem,if not,good excuse for a newer truck.
Well, I think the way it works is the filler tube is a coaxial type device, where the fuel is supposed to flow down the plastic inner tube, and the vented air then goes up the filler tube on between the outside wall and the plastic filler tube.
There is another vent tube on the top of the tank, but that is like 1/4" diameter, and I don't think Ford planned on that being the primary vent. I did replace both of mine though when I dropped the tanks last week, those lines were in bad shape.
I still think I need to somehow remove part of the filler tube right where the nozzle goes in. It is restricted right there for several inches. Can't be a good thing!
I have a flat bed but the problems are the same. I removed the small 1/4 vent line and roll over valve and fitted a 1" hose tail into the existing grommet. Then I ran some 1" fuel hose to the top of the filler to another elbow.
I also added a 1/4 tail to put the original vent line back on because this is where the air goes in as you use the fuel. Obviously I have fabricated fillers because the original ones dont fit with the tray but the cap neck and tank junction are the same. I would think with some fab skills and a little time you could do something similar. The only important thing is to get the 1" vent line closer to the filler cap than where the end of the nozzle is so the air is coming out above the fuel and you will get less foaming. In my experience the difference between nozzles is only slightly different flow rates and the foaming is caused by the filler on the truck.
Hope this helps some.
That's what I have been wanting to do, just have to take the time to do so. Mine foam and burp back at me. Our 92 fills fine, but it has better slope. What happens with the box on is that it has to go flat to get under, and fuel will puddle in there a bit, and then it kind of blocks the hose, then the fuel backs up. I haven't had time to monkey with it, but the hose needs to be downhill sloped all the way or they will back up too much.
the workhorse:86 F250 4x4 6.9 Diesel 4-spd, 4.10 axles
the other workhorse 92 F350 2wd crew cab,3.55 rear axle, 92 6bt Cummins, NV4500
the project: 78 F150 4x4 shortbed 351 auto Iowa Chapter leader, ASE certified parts specialist
Come on down and join us in the Iowa chapter, or your own local chapter!! Thanks, Roger
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