Disclaimer: I have my fuel gauge "Snubber" in the mail in transit right now from Tork Tek. Only a matter of days until I have my fuel pressure gauge in. I'm so frustrated with this "guess-work."

Ok, so about 1,500 miles ago I swapped in a new lift pump and new fuel filter. This past week, I noticed some 'tell-tell' symptoms of a fuel filter delta-p problem, reduced engine power / lugging / blowing blue smoke under load when the fuel pressure drops- all while uphill, but level ground and downhill is just fine.

I changed my fuel filter out yesterday with a brand new Wix. Ran great last night, for about 40 miles, then it had one instance of lugging under load, uphill, just as if the fuel filter was blocking. Happened again this morning, so I did some experimenting to get my facts straight:

-Any cruise under 2k rpm (or 70mph) can usually get past the hills 'OK'. If you step on it uphill, it quickly loses fuel pressure (or so I'm guessing) and starts to lug.
-Anything over that will drain the fuel pressure too fast and lug so badly, that you have to slow down (no other option, it's like the engine is stalling from lack of fuel) to about 60 or so until the fuel system "catches up."


Is this telling my that my new lift pump is not cutting it? I don't have very aggressive mods (sig), and couldn't think that I'm requesting too much fuel just cruising in the truck, no load on a trailer or anything?!!

I will have the fuel pressure gauge in in the next couple days. Should I consider putting a little boost pump in-line, pre-lift pump to help it out?

 

whats the fuel filter looking like when your changing it? hopefully pretty clean if it was only in there for 1,500 miles. also, is this something that was a noticeable change in one day, or a problem thats progressed up till now?

 

Started noticing it getting progressively worse over the last ~800 miles (2 weeks).

Filter is looking good, but I changed it anyway. Rather spend $20 on the troubleshooting for starters, ya know?

 

Update:

Again, let me remind you what's under the hood:
-New lift pump 2,000 miles ago
-New fuel filter a few hundred miles ago
-Tork Tek gauge snubber. Oil pressure gauge. nylon tubing.

This is at idle (full Op temp):

http://s110.photobucket.com/albums/n110/ApmCrx/Dodge%202500/fuel%20psi%20issue/?action=view&current=6idle15-20-flutter.mp4
Here's what's happening at 50 mph (full Op temp), fuel pressure wise:
( took multiple just so you can see it's chronically happening. these were taken one right after the other. Pedal was steady, holding at 50mph, until fuel pressure was lost, then it slowed a little. FLAT ROAD! NO HILLS!)


http://s110.photobucket.com/albums/n110/ApmCrx/Dodge%202500/fuel%20psi%20issue/?action=view&current=2cruise20-10-20.mp4
http://s110.photobucket.com/albums/n110/ApmCrx/Dodge%202500/fuel%20psi%20issue/?action=view&current=3cruise0-20psi.mp4
http://s110.photobucket.com/albums/n110/ApmCrx/Dodge%202500/fuel%20psi%20issue/?action=view&current=40psi50mph20psi.mp4
http://s110.photobucket.com/albums/n110/ApmCrx/Dodge%202500/fuel%20psi%20issue/?action=view&current=50-10-15-20-10-0.mp4


What's going on? Is it the new filter?

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What's causing the irregular fuel pressure? Air leak in system? Clogged/defective filter?

I'm trying my best to check all of the connections and lines for leakAge... But I'm gonna need this truck to pull my travel trailer in 2 weeks!

 

I would pretty much rule out the filter.

Need install details. How is it plumbed?

I would get a needle valve and remove the snubber (at leat temporarily), to see if that is the problem. After that, I would try another guage (0-60 psi), or test that one with air from an air compresser.

 

I will get a pic drawn up of how it's plumbed soon, as it's kinda spider-webbed with the WVO system. I just looked at all the lines, everything looks ok from the outside...

Gauge is known-good, but I might try another one just to be sure. Thanks

 

I missed the part about the WVO. Could be a clogged filter I suppose.

How do you know the guage is good? Just because its new? Do you have access to pneumatic test equpiment to check it?

Install pics would be helpful.

Like I said before, I would temporarily bypass the snubber and run fuel right into the guage.

 

Fuel does go right to the gauge. The snubber just has a tiny hole in it, or "Calibrated Orifice" as they call it. I purged the nylon line of air, so it's got straight diesel pushing on the gauge.
And I know the gauge is good because it's been running for the past year on my old car, accurately reading the oil psi. Plus, it's in the right range, but the oscillation of pressure is 'real-deal'. it's not just the gauge. you can definitely feel the loss of power when it goes to '0' for more than a few seconds. it makes you ALMOST have to pull off the road, but then picks back up and fuels it some more.

I don't have a compressor here at my new place yet. It's back in my shop a few hours away. Guess I'll have to just deal with it for now...

The WVO has a separate filter, and is controlled by a solenoid valve. the diesel filter ONLY sees diesel, and the WVO filter only sees WVO, there is no cross-contamination.

 

so you start and stop engine on straight deezel? does the lift pump do both fuels? or separate system all the way to the inj. pump?

 

I had similar symptoms once. It turned out that the second fuel filter in my tank was the culprit. The first filter in the tank is the one that's on the bottom of the pickup unit. That one can be removed, cleaned, and reinstalled. The second was INSIDE the pickup unit. I just removed that one completely.

Before dropping the tank, remove/clean the screen on the bottom of the fuel heater assembly. It takes a 17mm socket from under the truck. Only a little fuel will spill. If that's not clogged then I'd look to the pickup unit filters as being next in line to check.