Fuel pressure acting very odd

L

Leviathon

New member
Joined
Apr 10, 2016
Messages
59
So I've researched low fuel pressure countless times but all I've seen is fuel going straight to 0 for me that's not the case.

It started at idle it's 30psi and drops with throttle to about 15psi on full load. I recently deleted the heater, cleaned the screen and replaced the filter. Both were dirty as hell.

Now at first I bled the system, and cranked it. Started off fixed, about 17psi to 20 psi idle and goes up from there. One hard start after that but went right away. Now it's back to 30 psi idle and drops to 20psi with throttle bit tries to creep up...

This has me completely lost, does this sound like a OFV? I'm looking for obvious leaks and don't see any. I Crack the bleeder and pump the lift pump fuel shoots right out.

Sent from my SM-G925V using Tapatalk
 
I forgot to add. Stock fuel system besides afc tuning

Sent from my SM-G925V using Tapatalk
 
How is your fuel gauge plumbed in ? If your using a needle valve try loosening it up a little more.

Look up "ofv pen spring mod" it's easy and worth doing. If the pressure keeps dropping below 18-20 psi then it's probably your lift pump.

Now mine idles at 40-50 and I can make it read zero if I do a full wot run. Mostly due to he fact that I have a 140 gallon per hour pump plumbed inline between my tank and my factory location lift pump. It acts as a restriction this way but when the pump is turned on (wired up with a relay and 12 gauge wire) it idles at 65 psi and holds 30-40 psi when it's floored . I replaced my my stock lift pump before I tried the electric cheap pusher pump. It cruises around fine with the pump off but when its play time I turn it on . Much cheaper than an air dog or fass but it not as convenient

Anything below the low 20's for fuel pressure and the truck feels way slower.

what all has been done to your truck performance wise ? Pump work etc
 
Also what your describing sounds normal for a stock fuel setup.
 
Performance wise hardly nothing besides a BHAF and some afc tuning if you count that. Exhaust is straight 3 inch...not my ideal setup but what came on it I need to change it.

The gauge has a tork snubber valve in the IP to a hose that goes to my sensor for the gauge.

Sent from my SM-G925V using Tapatalk
 
See everything I've read states a factory setting would be 17psi-20psi idle. 25psi-30psi unloaded at 2500. That's what has me confused. I can make it drop as low as 15psi. The needle does shake at idle but I've always dismissed that as the sensor with the snubber valve just acting as it always will

Sent from my SM-G925V using Tapatalk
 
I have a Tork Tek snubber in my tool box. I like his valve spring tools, and pump gear puller but the snubber seemed to not work as well as a needle valve. I've installed mine on 2 different trucks and ended up pulling it and using a needle valve. I'll try drilling the orifice a little larger- not that it affects the fuel pressure but it seems to read slower than a needle valve.

Don't get to hung up on your the idle pressure, it looks fine . As long as it's not dipping to low at wot your fine, then again you don't have upgraded govenor springs yet.

Next thing for your truck should be some 4,000 rpm springs. I'm installing a set for a local kid tomorrow. They make the truck much more fun, way quicker. My 0-60 time was the same as my 1/4 mile when I had stock springs. Just the springs , afc mods, ofv mod , 3" pipe, lock up switch and my truck was running 15s and doing donuts with ease.

3" is just fine for your stock turbo. Just a waist of money going larger diameter . Put a bigger tip on it :)

After you add 4k springs if your fp drops low under wot then get a new cummins brand lift pump or buy a nice setup $$$ or buy a Procomp black 140 gph pump rated for alcohol and install it on the frame of you want to be cheap. I'd try a new lift pump first , after you install some 4k springs- skip the 3ks
 
I re read your post.

Mod the ofv , Get some 4ks. If the pressure is still low get a new lift pump.
 
Best advise I've gotten yet, thanks man I really appreciate it

Sent from my SM-G925V using Tapatalk
 
The last post I made is the minimum you should do if your trying to make the truck a little more fun. The long post is also what you should consider. If your not towing remove your plate and put it in your tool box. Timing would also be next. I tried 16* for awhile and it was better- little more response , it revved a little higher without popping/missing. Now I'm at 19-20* degrees and its even better throttle response, and revs litle bit higher. I'm going to try somewhere between 22-26* next but I'm pushing my luck according to the forums with the stock headgasket and I haven't over tightened my boots or bought studs yet. It still starts in freezing weather with a little over 19* timing.

Have fun
 
There are a bunch of threads that list the order of mods/upgrades for your truck. Sounds like you have gauges already
 
SCHMITTY said:
There are a bunch of threads that list the order of mods/upgrades for your truck. Sounds like you have gauges already
Click to expand...
Yes gauges were the first thing I did. The previous owner grinder the fuel plate to 100# but I'm finding that's useless considering I have a nv4500. Governor springs where the next thing I was buying. Also tune the afc more precisely. I will do the OFV mod and after the governor play with the timing on it. I have to track down an oil leak on long trips first though

Sent from my SM-G925V using Tapatalk
 
You must log in or register to reply here.
Top