Sudden loss of power- inconsistent symptoms

[clark]

Originally Posted by Wire89

Ok....just cruising around town the pressure will stay between 47 and 52. Accelerating into the highway it dropped to 40 quickly, then to around 35. As I get to cruising speed the pressure will build back up to 50. On the grade that I’ve testing this issue on the pressure drops to 20’s as long as I remain at higher rpm trying to gain speed, then will slowly drop all the way zero. It remained at zero for approx 1 mile to the top of the grade, at which point the pressure will back towards 50. So far, after two runs, the original issue has not repeated itself.

I’m guessing if I stayed at zero longer is when I’d get that sudden loss of power, and then decelerating allows the pressure to build, making it possible to accelerate again. Obviously fuel pump? Or look elsewhere first? Thanks all.

Sounds pretty much like what mine was doing. Changing the fuel pump is easy, $75 on Amazon. But you are probably going to drop the tank. Pretty common, search for the hutch mod. I removed the in tank screens and went with a pre-pump spin on filter. You can DIY it with this filter base.

But hey, not the Tranny!

[1der]

If you are dropping the tank, and you want/need more capacity, consider going to Aerotanks in San Berndino and getting a larger tank ~ 44 gals. Jake can do the tank install and pre-filter set up. Also eliminates the tank lining delamination issue, IF that is present.

Hutch mod recommendation is a good one. There is also a Harpoon mod???

[bet on black]

Originally Posted by 1der

Hutch mod recommendation is a good one. There is also a Harpoon mod???

yep, i did both to mine when i had the tank out to cut it down for the 4x4 conversion.

the harpoon mod is trimming down the filler tube and vent tube inside the tank, to as close to the tank as possible. my tank now fills all the way up on the first click, about 2 more gallons more than before the mod. no more topping off needed.

i used this kit for the hutch mod, but you can source the pieces yourself as well for a little cheaper: Riffraff Diesel Hutch In-Tank Fuel Mod Kit - Riffraff Diesel Performance

[Wire89]

Originally Posted by bet on black

i used this kit for the hutch mod, but you can source the pieces yourself as well for a little cheaper: Riffraff Diesel Hutch In-Tank Fuel Mod Kit - Riffraff Diesel Performance

Any issues using that tank mod kit on the van? I see the E-series are not listed for fitment and i came across a Driven Diesel kit that was not compatible with vans due the fuel tank. I do already have the 46 gallon after market tank, so not sure how different those caps and hoses are yet.

Did you also use their in-line pre-pump filter?

[bet on black]

I just used the in-tank parts of the kit. Worked fine. I think I had to trim and de-burr the tubing they sent, but it had all the parts needed to do the mod.

If you have your tank cut open to cut it down for a 4x4 conversion, do the harpoon mod too (trimming the filler and vent tubes), but unlike in the truck tanks, my tank had metal tubes. I used an abrasive cut off wheel to cut them and it would be hard to do and clean the tank out afterwards if you weren't cutting it open. One click and done at the pump tho. And that's pretty rad. Especially in the middle of the night, in the cold, when the wind is blowing, and you're fueling up at a station in the middle of nowhere, NM.

[VOODOO7.3]

Just saw this dilemma, so forgive me for late party entrance! First off, your problem was not likely the torque converter. The 2002-03’s all have stock triple disc converters. The sweet spot for the 7.3 is between 58-62 psi. Obviously, you are seeing FP problems, so make sure you do not run your engine below 40 psi, unless you want much bigger problems. The real test of fuel pressure is under load and like you said, once you hit that hill it falls on its face. Despite modern garage thinking, the diagnostic process should rule out simple and inexpensive causes first, and leave the suitcase full of money fixes for later! First thing to check is inspect factory fuel line fittings between the tank and your fuel pump. Make sure they are still plugged in tight and retainer clips are intact (not just hanging from fuel line). These connections work great under pressure but not under suction. Often they allow air to be sucked in which is what Hutch thankfully discovered and corrected. Next, try running with gas cap loosened or removed. Not likely, but there have been problems from incorrect cap causing a suction lock scenario. Next thing to do is go to any auto parts store and buy a clear inline fuel filter (for gas engines) with 3/8” hose barbs and 2 feet of 3/8” fuel injection hose. From under the front passenger side of engine, reach up there and push the 2’ fuel line onto the fuel bowl drain spout. Then install the clear filter with arrow facing away from bowl and put it where it can flow into an empty sports drink bottle or a milk jug. Now turn key on but do not start (that is KOEO -key on engine off), listen for the fuel pressure relief valve to blow off and note what pressure that is. Pop your hood and pull the fuel bowl drain valve open for maybe 15-20 seconds and repeat this whole process several times. Now inspect the inside of the clear fuel filter to see if there are a bunch of silver flakes in there. If so, it is your fuel tank delaminating. One other possible source is the fuel pick up foot inside your tank could be broken off. This scenario can be diagnosed if it runs fine on full tank but not when less than 1/3 or 1/4 tank. Report back with results and hopefully we can help you more.

[Wire89]

First, thanks to everyone for pitching in on solutions and advice. Finally got around this weekend to dropping the tank for the hutch mod. Took most of the day but it seems to have corrected the issue. Over the Grapevine, I-5 in CA, was able to sit comfortably at 70 mph and fuel pressure remained about 55. Never dropped below 52 or so in hard acceleration up hill. And was pretty consistently 58-60 psi on the flats at freeway speed. That a 15+ psi improvement just in cruising low load speeds. I’m posting a few more details below as I do have an aftermarket tank that influenced the process a bit.

Tank is a 46 gallon steel tank. In retrospect, this job would have been easier if I had two hydraulic jacks to better control the tank balance while removing and repositioning. The long 2x trick didn’t really cut it.

I had to lower my cabin A/C compressor bottle in order to get to the filler and vent connections. Then found it best to raise it back into place temporarily to get at the sending unit.

The sending unit on this tank sits in a depression on the top drivers side. I lowered tank just enough to be able to get the lift back underneath, using two 4x blocks. It worked best if the tank could rotate drivers side a little to get at all the fittings. No retainer ring on this tank, just a steel plate bolted to the top. Up to now, everything was smooth until the pickup foot fell off the bottom. Use that clamp on the mod kit.

Disassembling the sender unit we found that the screens were not actually that bad. However, the offices between the screen and the riser tubes were full of gunk, particles small enough to get through the screen. This tank is also, apparently, not as deep as most stock tanks. The measurement taken from the tank lid to bottom of foot was 11.25”. The hutch kit I bought from Riffraff is designed for around 13.5”. We had to cut about 1.5” off the main tube to fit remaining parts. Last here, no harpoon mod needed as filler tube was designed to fit right at top of tank.

Lifting it back place and aligning connection points on a wobbly floor jack may have been most time consuming. I then mounted the Riffraff inline filter just between the compressor bottle and fuel tank. Note, the Riffraff product does not come with the fuel line fittings.

Now on to more fun things...