Is anyone else having their fuel pressure jump around from 9-17psi on their edge when the temperature is cold outside(50 and below)?

I have a fass 95/95 but it did the same thing when I had the factory lift pump

Any ideas why its doing this?

 

is it while driving or just on startup does it do it after engine is up to operating temp.

 

if its when it first fires up and is cold it could be the heater grid pulling power. the lights will dim and it will pull some power from the fuel pump also.

 

I'd agree with the grid heaters pulling it down. But 8 psi seems pretty steep. Mine would only drop 2 or 3 psi when the grids came on.

 

Funny you brought this up. I had a similar problem last week when it was -20 here. Occasionaly when driving(just at cruise on the highway) the Edge's low fuel pressure alarm would go off(its set to 4psi). It would also jump up to 30psi. Changed the filter, no effect. My tank was running low(light was on). When I filled up I popped the hood and checked the wire going to the sensor(unplugged it and plugged it back in). After that it was fine. Not sure if it was the sensor or the low fuel. Thinking it was sensor due the the erratic readings. Been fine ever since.

 

Mine always does that when it's cold and the heater grid is running (and I have a MECHANICAL GUAGE). I guess the heater grid pulls enough juice to make the LP wish it had a little more. Once I figured out what it was...I quit worrying about it. But now that you've reminded me again...I'll probably worry about it on and off again until I forget about it.
Thankx,
Puke

 

Man, these pumps tick me off. I just put one in 1000 miles ago and its crap again. I would love to find a easy & reasonable solution. It seems like these things could be replaced by a pump that was regulated at 20 psi. I hate these pumps. Maybe I'll put a second 12volt wire to it from the acc. ANy thoughts? I'd run a 2nd ground to it too, just incase that was part of the issue. Rrrr i hate these pumps

 

I would not go too high on the psi. The last thing you want is for your filter to get a little dirty and your pressure to be enough to start pushing things through there that you don't want. I know that 20 psi is low...as far as filters and pressure go...but do not underestimate what constant pressure can do to a screen or filter ...etc.,

By the way, if you had one go bad that fast,...I would really be making sure I changed the fuel filter tat the same time. That happenned to me and I now believe it was due to me not changing the fuel filter often enough.

 

Although thats a good idea, its not the heater grid.

Remember its the temperature outside...not the temperature of the truck.
It continues to jump around as long as the temperature outside (Im guessing temperature of the fuel is cold) even when the temperature of the truck is 190

What would cause it to do this?

 

If it continues to jump around when your temp. is @ 190. Then you better check your connections.
You better change your fuel filter if you haven't.
You better put a mechanical guage on it to make sure it's not an internal electrical connection (you can get one to screw into one of the threaded holes in the top for fifteen bucks or so.) of your guage.

By the way, if you have your guage attached to the pre-filter side,..then my tiny opinion says it HAS to be one of the following

1) lift pump getting ready to die
2) bad guage or connection to guage
3) plugged intake (in your tank...the pickup tube has a filter of sorts over it).
4) small possibility your tank breather hole could be plugged. I've read this a few times on this site...You could check that easy enough by leaving your cap a little loose just to check it.

I can't think of anything else it could be. And I've read this site (and in the past...the "other" site we don't mention much) quite a bit and can't think of anything else.

OHHHH, Wait just a minute....It could be one more thing. It happenned to me on my harley. Please hear me out, because it could also happen to you and you would have a hard time finding it. Hear me out.
1) My harley was reading low volts every time I would take off, but when I was sitting still it would read the standard 14 volts.
2) Took it to a custom shop in L.A. that just deals with harleys. (also had it to the van nuys harley shop also)
3) They did some work and said they'd have to replace the stator (equivalent of the generator on your truck).
4) I got it back.... When I took offf......the voltage would go from 14 down to below twelve (on the guage).
5) I finally decided they were all morons...and I duct taped an expensive Voltmeter from my recording studio to my gas tank, and hooked the wires here and there..etc.,
6) FInal diagnosis.....When I would take off....the bike guage would go from 14 down to 12 or 11 etc., But, my expensive guage from my studio would stay right at 14 or whever it was supposed to be...

Conclusion:
Only the guage was bad....and ONLY when I would head out down the road...something from the wind was cooling a connection just enough to make the meter read low..

I should have had that hunch earlier...because I never did have a dead batter, etc.,l...or al the things that should happen if your stator is going bad.

The point I am making is this.....You may have a generator that is not putting out a good constant voltage...or a bad connections somewhere in the line. Go ahead and tape a Voltmeter in your cab and run the wires to your mains and see if INDEED that your pump pressure fluctuations are following your "alleged" voltage fluctuations on your mains.
If you do this...you will at least eliminate that possibility. I know it sounds complicated...but it's very easy..

If you DO find out that you have a voltage on your mains that is fluctuating with your pressure guage...then you have an electrical problem to deal with. As I see it.


I hope that makes it at least clear as mud.

Puke