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Opinions needed - Performed Optical Bump

Found the ground problem. Was on the frame at the fuel tank. Got the lines primed and now I’m at a no start condition and dead batteries. Oh it just gets better!
 
Got it running. I plumed a gauge in on the remote filter housing and I see about 5 psi with key on and between 4 and 5 idling. Sad part is I can’t rev it and watch the gauge
 
So. A concerned question.... the ground problem I found was the eyelet ground on the frame was off from my own doing about a month ago due to me probing the harness checking the fuel gauge. With that said. The truck apparently has been running all that time without the lift pump working and I didn’t know it.. shame on me. Have I possibly caused irreversible damage to the IP. Also what should the line pressure be from the lift pump with key on and idling.

now I’m headed inside to go kick myself in the A$$ for this mistake:sorry:

I will be looking into an inexpensive gauge to mount in the cab real soon because of this experience
 
Jaryd said:
I use a boost gauge from Advance Auto for my fuel pressure gauge. I like the boost guage for fuel pressure because it'll let you know if you ever go into a vacuum.
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I would have never thought of that! Curious though. Did you use something to keep the fuel from going into the cab incase of disaster? I was looking into that and only found what they call an isolator but those puppies are as expensive as a high dollar electric gauge set!
 
It shortened the ip life but no telling how much. I wouldn’t worry about it at this point- it is what it is.
The air intrusion is going to have added in as well.
The air leak could be before where you attached the line. Rusty line from the pickup tube in the tank is common- also part of the reason I go to dropping the tank right away.

Once running-
Swap in clear tube between filter and ip. Watch for the bubbles there. If there is bubbles then keep moving backwards toward the tank until you can find where it is at.

On my phone i cant enlarge the pics well. But i think the fuel hose towards the front on the filter looks over pinched by the hose clamp. Pay a lot of attention to the connection point - that is most common failure points.
 
Oh yeah, gauge.
I ran stainless steel 1/8” into the cab- not the smart system. I have since removed that.

My best suggestion at this point is electric fuel gauge. Use steel fittings directly at the ip inlet adding a “T” fitting there. Screw the sensor into the tee. Many people have had rubber line right at the ip connection fail and cause a world of issues. Thats why reading it from there is crucial. The cost issue is simple- it sux. Used to be gauges could be found low cost that worked ok.
Short term, gst the gauge from harbor freight. Still the lace the T at the ip inlet and just run the line where you have to- but replace it asap.
 
A thought just occurred to me when reading another thread that the return line fitting on the IP has a pressure regulator and check valve built in. I’m curious if these things are common to fail. Just searching online there are several threads out there on them
 
I hot a Mr Gasket fuel gauge. It is a live gauge so a tube is run into the cab.
I dont remember the price but, it was not a lot of money.
I got a 3 gauge pod and am planning on a RH cylinder temp gauge, an oil pressure gauge and an fuel pressure gauge. All of them electronic units. Might even do as suggested and incorporate a switch and run two fuel pressure sending units on one gauge.
 
dbrannon79 said:
I would have never thought of that! Curious though. Did you use something to keep the fuel from going into the cab incase of disaster? I was looking into that and only found what they call an isolator but those puppies are as expensive as a high dollar electric gauge set!
Click to expand...

I have the line coming into the cab without a isolator. One of these days I’ll get a isolator for it. But for now I just check it every now and then for leaks.
 
dbrannon79 said:
A thought just occurred to me when reading another thread that the return line fitting on the IP has a pressure regulator and check valve built in. I’m curious if these things are common to fail. Just searching online there are several threads out there on them
Click to expand...
Whoa there big guy. Something’s a miss here. Either I didn’t understand you right, you didn’t understand a thread right, or whoever wrote it didn’t understand right.

Keep in mind your engine used in different rigs, generators, etc. SOMETIMES had extra parts yours may not have. My Hummer and all hmmwvs for instance has 2 inline check valves your pickup never had. AM General knew lift pumps fail often and wanted to help starting incase that happens and someone is shooting at the soldier. Ruin the longevity of the engine but keep Private Pete alive.

Your original lift pump should have a check valve in it- but not all did. The ip has check ball functionally seated solenoid to stop fuel flow which kills the engine and when engaged allows fuel flow. Regulator? Not in your truck. Hell your fuel pressure is too low from factory as it is.


You are going down a deep rabbit hole here. It is easy as can be to chase many ghosts of what ifs and maybes. Don’t do it.
Once I saw the video of the air when starting then again around the 54 second point iirc - that is it. You 100% have air intrusion problem that has to be solved. I said go ahead and replace lift pump if you are 100% it is bad because maybe it is ALSO source of the air intrusion. Otherwise I would say don’t bother with it until you solve the air problem.

If someone added 5 check valves. 3 regulators, and a Dr.Suess wizz bangler- i don’t care because they don’t matter. You are sucking in air somewhere and it needs resolved- period.
Forget everything else and fix the leak.
 
So when testing for leaks you were using compressed air and that finally pushed air all the way through the IP. Again NORMAL and don't overthink it. You are looking for leaks, period. The IP normally leaks some from lift pump PSI out the fuel return. These slow leaks are why the fuel return is submerged in fuel in the tank: so the system doesn't siphon itself dry and you got to reprime the fuel system the next day on the starter...

Now you have "fixed" a problem. Start over and redo the air test when running. It's possible you fixed the "air" with the lift pump as the IP is no longer pulling on a dead lift pump restriction.

Yes, new video of the clear return line like you did before.
 
Yeah y'all are right. Since I repaired the ground for the lift pump I haven't seen any more air in the clear return line, but I did have a hell of a time this morning getting the truck started and of course I was in a hurry and didn't look to see if there was air bubbles. So I still need to look for problems. When it did fire up, it was bellowing out white smoke and barely running, I had to mash the pedal for it to straighten up and run. after that I didn't have any problems getting to work.

After finding and fixing the ground the truck started on a dime all weekend but I also noticed on Sunday that with key on fuel pressure went to 5psi and once started the pressure dropped to 0, but still fired up on a dime. Saturday is was staying constant at 5 while running so I still have an apparent problem that I feel like is pointing to the lift pump.

when the pressure dropped to 0 and was idling I did try pinching the inlet hose to the IP with my fingers momentarily and pressure would climb to 2 or 3 psi and drop to 0 again when I let go, so I think there is a flow issue with the lift pump.

I did verify the lift is working while the engine is running, but I also only have maybe 4 to 5 gallons or so left in the tank. I don't want to fill it until I find the issue so I think at this point I think I may plumb in my auxiliary tank in the bed, while looking for a better lift pump and pull the OE tank to check and replace things there.

Any suggestions on a decent lift pump? or what pressures I should be seeing with key on and on idling? the pump I have on there now is a Carter P74143 which when I purchased it, it showed for my truck by application but now when I try to find the specs on it, I can't seem to find it's pressure or flow ratings. when I replaced it about a year ago, the old pump was still working but I just replaced it for good measure. I still have the old one I kept for a spare for on the road disaster. I will have to look and see if the old one has any markings to identify it.
 
You want 8-14 psi. Under 5 is beating up the ip, getting into zero or vacuum really tears it up fast.
Finding pumps that do those numbers is stupid expensive. If I was rich and famous like most of y’all running the ds4 ip- Fass is hard to beat. Having the attached filter set up that stops nearly 100% of water and contamination and eliminating aeration at same time makes the pain of the million dollar price tag easier to justify. But gonna need pressure gauge for setting it down to that pressure.

One of the advantages of the db2 owners - 5psi is tops for us, so much easier to find lift pumps that can do that and live.

I am still convinced you are sucking air somewhere, not just a LP issue.

Are you familiar with FTB MOD? Enlarged fuel line from filter to ip using 3/8 line including ip fitting instead of factory 5/16”.
 
Keep in mind air bubbles in the fuel system can be either an air leak OR a restriction in the system. If the limp pump stops working that was probably the air issue. The IP can pull enough fuel to keep the truck running even with a inop lift pump. The lift pump was more than likely a restriction when it was off and caused the IP to pull the system into a vacuum creating air bubbles.
 
Will L. said:
Are you familiar with FTB MOD? Enlarged fuel line from filter to ip using 3/8 line including ip fitting instead of factory 5/16”.
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Yes, with the remote mount filter I have and eliminated the original filter manager, it uses 3/8" line from the steel line from the lift pump to the IP, but I have not enlarged the fitting that's in the IP. that was the last step, I just need to buy a fitting for that.
 
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