Engine/Transmission (1998.5 - 2002) One-time low Fuel Pressure reading -- serious problem or just an anomaly?

[Troubleshooter]

OK, so here’s the scenario: Driving the ’01 CTD back from work last night with the fuel pressure at 15-16psi. Floored it one time to get across a busy intersection. All is well. About five miles up the road, I glanced over to the gauge which is now reading ~2psi. Narrow country road with no place to safely pull over (no shoulder or soft shoulder and it’s raining) so I just sort of babied it up the road. A few minutes later the needle jumps to 6psi, then comes back on up to the 14-16psi range, so I drove it the rest of the way home. Popped the hood and checked wiring from the sending unit; listened and the FASS was still humming along (but no way to tell whether it cut out during those few minutes of low pressure as I can’t hear it inside the cab when driving). The truck is throwing a P1693 code, and Smarty shows both the P1693 and a P0206, which I THINK is normal with the Smarty. No dummy lights have come on.



Took it out again last night and this morning, and since then it’s started normally and the FP has remained in the 14-16psi range. The FASS has been in for about a year now, and the last mod was installing the Smarty about two weeks ago. No loss of power driving it this morning. My questions for y’all:



Any ideas where I should look next?



How badly did I screw up the VP-44 and / or other systems?



If it happens again, what immediate action drills should I take? (i. e. , keep moving slowly until I get to where I can work on it, or pull over and shut the engine down immediately)



How much is this gonna cost me?



Thanks in advance for any advice or wisdom!

 

[fox]

Don't get worried over this.

It could simply be the gauge acting up, or somehow the tank let a little air in.

This is why the factory won't put the fuel pressure gauge in as factory equipment. We would know they took a short cut!!!

 

[Troubleshooter]

Well, it happened again today and I think that we can eliminate faulty gauges. When I went to start it up after work, I turned the key to the RUN position and saw 0 psi and didn't hear the FASS kick in. Just to experiment, I turned the key to START and it started right up without hesitation, so I shut it back down again. Scratched my head, said a few choice words, and tried it again. This time I heard the FASS kick in, saw the needle on the FP gauge rise, and then continued to turn the key (once the WTS light went off of course). The fuel pressure gauge read 14-15psi all the rest of the drive.



So now I'm thinking that it's either a gremlin somewhere in the wiring, or the FASS is starting to go bad on me. And that leads us back to the earlier question regarding what damage, if any, may have occurred to the VP-44 when it ran for several minutes at 0psi. Any ideas?

 

[blacksheepdiesel]

It is normal for the lift pump to give a short burst of fuel when the key is first turned on and then it waits until the engine is turning over to get going again. Working as normal.

When you are driving down the road and it happens that is another matter entirely. Could be a hiccup in the gauge or sending unit. Or the FASS could be malfunctioning. Do you also have a low pressure light? I recommend that AND a gauge as they are a back-up for each other. If the gauge shows low but the light is not on the sending unit or gauge is at fault.

Godspeed,
Trent

 

[Troubleshooter]

Thanks for the replies. Turned out to be a gremlin in the wiring. Tightened things up a bit and it seems to be working well now.

 

[Mad Bomber]

I have the FASS also and found out that my screen in the tank was cloged because I could drag it way down