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94-98 PowertrainDiscussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission Ect...NO ADVERTISING
The truck is in the sig. I am having low fuel pressure issues. After replacing the fuel filter, pre-filter, and lift pump I can not get my fp back up to where it should be. My tork tek OFV is maxed out. I see about 20 psi at idle when it's cold or halfway warm, but after a long freeway drive the idle psi drops down to about 14 psi. Under load I can pull it down to zero easily and I see about 19 psi cruising at 65 mph. Sometimes I get spikes of up to 30 psi at certain speeds but I'm mostly maxing out at about 22 psi. Every time I've changed a fuel filter I've had to turn my OFV up more to see the correct pressure. Now I'm just at a loss. Since my fp was decreasing slowly I thought my lift pump was on it's way out. But after changing that out it did nothing. Maybe a supply line plugged up with crap? When I drained my filter there was a fair amount of junk in the drain pan but the filter looked fine. Any help is much appreciated.
There's a guy floating around here with 780k on his unrebuilt cummins. Now, according to duramax and ford guys, his truck should have fallen completely apart around the engine 7.8 times, since they all know that dodge trucks are junk and only last 100k before they spontaneously disassemble themselves while going down the road. That has happened to me 2.76 times, and both times I was only wearing boxers while driving so it was really embarrassing.
Not know for the best have you hooked up a independent FP gauge to confirm the pressure??
Also have you pinched the return line to see what that does??
I will try an independant gauge as soon as I can. I'm very unsatisfied with my glowshift gauges. I'm trying to convert over to autometer gauges. But I'm in college and money is really tight. And I haven't pinched the return line. If it spikes to 60 psi or more the lift pump is good right?
Yep, pretty much. If it spikes to 60 or so but you find you're actually still getting low pressures at high boost/load, you have a supply problem, most likely before the lift pump. At that point you're looking at dropping the tank (or raising the bed), blowing out the supply line, and carefully checking the pickup assembly. This isn't really that bad of a job, especially if you decide to drop the tank and have two floor jacks available. That's the way I do it, others prefer to raise the bed.
By the way, a cheap accurate fuel pressure gauge setup can be rigged up by drilling and tapping the banjo bolt on the input of your injection pump with 1/8" npt threads. A grease gun hose (yes, the kind you lube your suspension with) will then screw right in. Get the longest one you can find, or connect several together using female unions, and put almost any gauge that will read to 60 psi on the other end of the hose. A pressure gauge off an old welding torch setup will work, an oil pressure gauge will work, you get the idea. Just make sure you put a needle valve somewhere between the pump and the gauge. You'll almost completely close the valve, but not quite. That dampens the pressure pulses the lift pump puts out and keeps the gauge from getting hammered to death. Clip it under the windshield wiper arm and go for a test drive. When you're done, screw in an 1/8" npt plug to close the hole you drilled into your banjo bolt.
If you do this, two important things: Drill the hole from the inside out. The shape of the inside of the banjo bolt will guide the drill bit where it needs to go. The other, more important thing: MAKE DAMN SURE YOU GET EVERY MOLECULE OF METAL SHAVINGS THE HELL OUT OF THE BANJO BOLT. There is absolutely no filtration between that part of the fuel system and the injection pump. The internal tolerances of the pump are fantastically tight. A piece of metal you can barely see would be roughly equivalent to a small boulder jammed between a piston and cylinder wall if it gets into the barrels and plungers inside that pump. You really can't fathom how precise the clearances are in this area of the fuel system. So, if you do this (which I encourage you to do), just get the s*** clean.
Yep, pretty much. If it spikes to 60 or so but you find you're actually still getting low pressures at high boost/load, you have a supply problem, most likely before the lift pump. At that point you're looking at dropping the tank (or raising the bed), blowing out the supply line, and carefully checking the pickup assembly. This isn't really that bad of a job, especially if you decide to drop the tank and have two floor jacks available. That's the way I do it, others prefer to raise the bed.
Okay cool thank you for the information. I'll be dropping the tank if anything. As I will probably doing the repair in my dorm parking lot. I'll be taking a look at all of this though as soon as I can.
By the way, a cheap accurate fuel pressure gauge setup can be rigged up by drilling and tapping the banjo bolt on the input of your injection pump with 1/8" npt threads. A grease gun hose (yes, the kind you lube your suspension with) will then screw right in. Get the longest one you can find, or connect several together using female unions, and put almost any gauge that will read to 60 psi on the other end of the hose. A pressure gauge off an old welding torch setup will work, an oil pressure gauge will work, you get the idea. Just make sure you put a needle valve somewhere between the pump and the gauge. You'll almost completely close the valve, but not quite. That dampens the pressure pulses the lift pump puts out and keeps the gauge from getting hammered to death. Clip it under the windshield wiper arm and go for a test drive. When you're done, screw in an 1/8" npt plug to close the hole you drilled into your banjo bolt.
If you do this, two important things: Drill the hole from the inside out. The shape of the inside of the banjo bolt will guide the drill bit where it needs to go. The other, more important thing: MAKE DAMN SURE YOU GET EVERY MOLECULE OF METAL SHAVINGS THE HELL OUT OF THE BANJO BOLT. There is absolutely no filtration between that part of the fuel system and the injection pump. The internal tolerances of the pump are fantastically tight. A piece of metal you can barely see would be roughly equivalent to a small boulder jammed between a piston and cylinder wall if it gets into the barrels and plungers inside that pump. You really can't fathom how precise the clearances are in this area of the fuel system. So, if you do this (which I encourage you to do), just get the s*** clean.
I have a tork tek snubber and banjo bolt combo hooked up to 18 inches of grease gun hose. The problem right now is the crappy gauges that I have. I'm going to try to purchase some form of an accurate gauge or see if a local shop will allow me to use one of theirs. Thanks for the input though, I appreciate it.
I'm experiencing the same problems, can't give long term numbers for FP as I've only ever hooked up a test gauge while parked. Does your truck smoke at all under load? Mine dries out really quick and will barely even haze under full throttle and I have no fuel plate in it.. Im awaiting a delivery tomorrow: snubber, 1/4" oil line, fuel heater to lift pump rubber elbow, a draw straw, and enough 1/2" & 5/16" fuel hose to run from the tank to the lift pump. I'll post back when I get real world results from the FP gauge
__________________
96 2500 4x4 EC LB NV4500 Stock: AFC Tuned, Boost, pyro, FP gauges, 5" Straight Pipe, BHAF, SDX II's, 4GSK, 17*, ADII 165, South Bend Dual Disk.
i had a fuel pressure problem as well and couldn't get my pressure right. after replacing everything like you did, my problem was my glowshift gauge..but the problem was when i rehooked up my sender i put the ground wire on the sender wire post. "G" is for the sender. i just figured the G was for ground. i felt dumb but then everything was good to go.
figured id throw that out there. maybe you did the same thing i did.
I'm experiencing the same problems, can't give long term numbers for FP as I've only ever hooked up a test gauge while parked. Does your truck smoke at all under load? Mine dries out really quick and will barely even haze under full throttle and I have no fuel plate in it.. Im awaiting a delivery tomorrow: snubber, 1/4" oil line, fuel heater to lift pump rubber elbow, a draw straw, and enough 1/2" & 5/16" fuel hose to run from the tank to the lift pump. I'll post back when I get real world results from the FP gauge
The truck hazes under load and never signs off. I took it to my local dodge dealer and the mechanic says that everything is flowing fine and working as it should, it's just that the stock lift pump can't keep up with the truck.
Quote:
Originally Posted by cumhands
i had a fuel pressure problem as well and couldn't get my pressure right. after replacing everything like you did, my problem was my glowshift gauge..but the problem was when i rehooked up my sender i put the ground wire on the sender wire post. "G" is for the sender. i just figured the G was for ground. i felt dumb but then everything was good to go.
figured id throw that out there. maybe you did the same thing i did.
Everything is hooked up correctly. It looks like my problem is that the stock pump just can't keep up with the demand.
So what do you guys think? Would it make sense that I need a performance lift pump? If I do, what should I get? I've heard that some pumps (fass or air dog maybe) don't do well in cold weather. I can't have this truck acting up when it gets cold in the PNW.
It looks like my problem is that the stock pump just can't keep up with the demand
.
The HP in your sig is only about half of what the stock lift pump will support.
Make sure no hoses are kinked especially the one from the fuel heater to the lift pump.
If your FP gauge is electric I wouldn't trust it very much.
__________________ Bill
'95 2500 4wd auto
'95 3500 5 speed heavy hauler
Stock for one day
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I'll be taking a look at all of this though as soon as I can.
Stock: AFC Tuned, Boost, pyro, FP gauges, 5" Straight Pipe, BHAF, SDX II's, 4GSK, 17*, ADII 165, South Bend Dual Disk.
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