Dodge Cummins Diesel Forum banner

1 - 20 of 21 Posts

·
Premium Member
Joined
·
266 Posts
Discussion Starter #1
I installed my fuel pressure gauge today. The gauge works because when I turn my truck on the needle goes to below zero then back to zero (the instruction book says thats a self check). But it does not read any pressure. This is how I set up the sender. Is there anything wrong with what I did or is the sender bad? Any help would be great.

 

·
Rescue Tower
Joined
·
10,827 Posts
It sounds like you have the power on the gauge wired backwards. A normal self test does a full range sweep from zero to max, then back to zero... not below zero, then back to zero.

Are you bypassing the factory filter? If not you need to pull the fuel pressure after the last filter (factory) Does the AD run? You shouldn't need a hose clamp on those barbs either.
 

·
Registered
Joined
·
255 Posts
shainer i have a set of electric autometers and the do the same. when you shut the truck down they dont go to zero then when you power them up the go to zero then they read what ever.
 

·
Premium Member
Joined
·
266 Posts
Discussion Starter #4
The airdog does run, and I ripped the factory filter out. So that fuel line goes directly into the vp.
 

·
Premium Member
Joined
·
266 Posts
Discussion Starter #5
Also when I unplug the sending unit, the gauge goes to max psi. Not sure if that helps diagnose the problem.
 

·
Registered
Joined
·
1,958 Posts
It sounds like you have the power on the gauge wired backwards. A normal self test does a full range sweep from zero to max, then back to zero... not below zero, then back to zero.

Are you bypassing the factory filter? If not you need to pull the fuel pressure after the last filter (factory) Does the AD run? You shouldn't need a hose clamp on those barbs either.
Since it sounds like you have an electric fuel pressure gauge, then
:ditto:
The way you have your's set up is a bit different than mine, I ran mine closer to the vp, like this:
 

·
Premium Member
Joined
·
266 Posts
Discussion Starter #7
I am guessing that your gauge works. I see you have a hose coming off of the fitting going to your sender. Do I need this? Or can the sender screw right into the fitting?
 
Joined
·
2,770 Posts
It sounds like you have the power on the gauge wired backwards. A normal self test does a full range sweep from zero to max, then back to zero... not below zero, then back to zero.

Are you bypassing the factory filter? If not you need to pull the fuel pressure after the last filter (factory) Does the AD run? You shouldn't need a hose clamp on those barbs either.


I have had a full sweep Autometer electronic stepper motor fuel pressure gauge for over 3 years with zero issues.

Shainer is correct on all counts.

Your gauge's power on self test is failing. It should react as Shainer posted above upon power up.

Your sender should be closer to the VP44, after the last filter, for a more accurate measurement. Plus that sender is delicate & expensive.
It would be better to have it under the hood rather than under the truck. Plus the wiring would be much shorter.

Having the sender directly into the T-fitting is fine since it's not directly mounted on the engine and isolated from engine vibrations.

Although I have a pressure snubber protecting my sender, one really isn't needed since the sender is mounted in rubber line.
The S.S. extension line that Dennhop has isn't needed.

Lastly, as Shainer mentioned, the screw clamps on the pushlock barbs are a no no. Not required nor recommended on push lock fittings.
See Dennhop's pic, no hose clamps!


I hope this helps & you get it working...Joe
 

·
Premium Member
Joined
·
266 Posts
Discussion Starter #9
When you say the power on self test is failing, does that mean I have it wired wrong, or that my gauge is bad?
 
Joined
·
2,770 Posts
When you say the power on self test is failing, does that mean I have it wired wrong, or that my gauge is bad?
It's hard to say. Have you checked out all the connections to make sure they are correct?

Did you have to extend the wires in the harness from the sender to the gauge?
If yes, make sure that no wires are crossed over.

If all the wires & connections check out, perhaps a call to Autometer for more info.
The gauge or sender could very well be bad.

...Joe
 

·
Registered
Joined
·
285 Posts
why not use the tapped 1/8'' port on top of the airdog thats where i put mine and thats where airdog puts there low fuel pressure warning light sender should i move mine.
 

·
Cummins Power Addict
Joined
·
1,040 Posts
I had an issue like this with my gauge, ended up being a loose wire or two on the harness, must have pulled them out when running the wires. Maybe just check all your wiring set up, for loose connections and improper ones...
 

·
Registered
Joined
·
1,958 Posts
The reason I have the s s line, is that I'm running a 3/8" line to the bottom of an isolator, and then my rubber tubing from there to the gauge...just how I got the gauge, so figured I'd hook it up that way.
 

·
Premium Member
Joined
·
266 Posts
Discussion Starter #14
I didnt know that airdog had a port. I did extend the harness but I checked the wires with an ohm meter and they are all good. I got 12v going to the gauge, a good ground. Autometer is closed, so I will call on monday. But I have no clue what it could be.
 

·
Rescue Tower
Joined
·
10,827 Posts
why not use the tapped 1/8'' port on top of the airdog thats where i put mine and thats where airdog puts there low fuel pressure warning light sender should i move mine.
You can use the AD port as long as you bypass the factory filter. Otherwise you need to locate the sending unit after the last filter in the system. The goal is to get the most accurate reading of what the IP sees. If you can get your hands on another FP gauge you can test its function by temporarily connecting the appropriate leads to a +12v power source to see how it functions. I have a habit of doing that on new gauge installs just to make sure they work prior to getting everything mounted.
 

·
Rescue Tower
Joined
·
10,827 Posts
I didnt know that airdog had a port. I did extend the harness but I checked the wires with an ohm meter and they are all good. I got 12v going to the gauge, a good ground. Autometer is closed, so I will call on monday. But I have no clue what it could be.
Are you positive you did not roll your wires when you extended them?
 

·
Premium Member
Joined
·
266 Posts
Discussion Starter #17
I am 100% positive I have checked them and rechecked them. Is there any way to check if the sending unit is working by using a volt meter or something?
 

·
Cummins Power Addict
Joined
·
1,040 Posts
Not sure if this will help, but here's some of the email from the AutoMeter guy I talked to about my problem:

My sending unit info:
4590-0023-12
0-100PSIG
S/n: 070051223
Wiring Harness and some troubleshooting advice:
Looking a the rear of the connector, as if it was plugged in, and with the locking tab on top:

x x blk blk red
x x x gry ppl

After you get this back together, and if you are still having a problem, then use a pin to back probe the wires at the connector. You should see at or very near 5v on the gray wire, and you should see a signal at the purple. The signal at the purple depends on the pressure reading and can be between 0 and 5v. Both measurements are to be done with a volt meter set on DC volts.
Hope this is of some help to you.
 

·
Premium Member
Joined
·
266 Posts
Discussion Starter #19
My wires are in that order. When they say "use a pin to back probe the wires at the connector" what do they mean? Do I check the voltage of the wires that plug into the sender. Or do I check the plug at the gauge, to see if the gauge is putting out 5v at the gray wire? Sorry for all the questions, i am just confused.
 

·
Premium Member
Joined
·
266 Posts
Discussion Starter #20
Alright, I measured the voltage coming out of the gauge and I have 5v coming out of the gray wire. None for the purple, but that is because I had to unhook the connector to check the voltage. So I think my sender is bad. And in the instructions it says on power up the needle will go backward (below zero) then back to zero as a self test.
 
1 - 20 of 21 Posts
Top