Fuel pressure reading 0

[PABowhunter]

Well I made it home without any further issues. Want to put in a good word for Curtis from Vision Diesel (who I bought the fuel system from). I texted him on Saturday and he called me back within two minutes to help me troubleshoot it.

I'm still a little confused about a few things, but everything seems to be running fine now. Here's the long version. Maybe someone can point out something I'm overlooking.

I went to start the truck on Sunday morning and the fuel pressure came right up to 67 psi. Started the truck and all was good. I quick crawled under and took a voltage reading at the pump. was reading around 8 volts. Then I heard the pump groan (truck is still running) and the psi dropped to 0. Crawled underneath real quick and took another voltage reading. Got 5 volts this time.

This didn't make sense to me so I turned the truck off and started taking voltages further back. The relay for the pump gets its power off the drivers side battery. I took a reading right at the battery and got 9 volts. Checked the passengers side and got 12.5 (all the wires were still connected). Started the truck again and took voltages at the drivers battery: 6 volts, passenger battery: 14.5 volts, and alternator: 14.5 volts.

At this point my mind is going to the batteries or cables now instead of the fuel pump. I knew there was an autozone about 2 miles away so I drove the truck over there and had them test the batteries. The drivers side showed it needed to be charged and the passenger side checked out good. They charged it inside for an hour and everything checked out. I put it back in the truck and checked my voltages at the batteries and pump and everything was good. At this point I just put the hammer down and got home as fast as I could. Fuel pressure never dropped below 65 psi. I did see the gauge flutter a couple times (which it normally never does) but only 1-2 psi.

Today I looked around the truck some more expecting to find a bad connection between the batteries. I was guessing the drivers side battery didn't get charged and the fuel pump was the only thing connected to it which in turn drained it over time. I disconnected the positive connector cable and ground cable and the voltages all checked out. Didn't get any drop from the passenger battery. The voltage at the fuel pump was reading 12.5 with it off and 11.25 with it running. I gave all the terminals and connectors a good cleaning when I was done.

I'm saying it was just a bad connection between the inside of the connector and the terminal. Unless I'm missing something....

I have a couple other questions on the issue too:

1. How was my truck still running, and running well, with 0 psi of fuel pressue? Will the large volume of the lines make up for this?

2. Will running a pump at a lower voltage for an extended period of time harm the pump?

 

[gnxtc2]

The motor will still run with 0 pressure. I disconnected my pump connector and the truck still ran. I believe that the injectors will form a suction and pull fuel. I don't know if 0 pressure will damage the injectors? It's not like the fuel supply was shut off.

Maybe an injector builder will chime in.

It's a DC motor so it can run on lower voltage. If it was an AC motor, it'll be a different story.

Billy T.
[email protected]

 

[PABowhunter]

I figured I should be okay with the DC motor. I know low voltage will burn up an AC motor quick.

 

[ghohouston]

Yeah, low fuel pressure will ruin injectors. Not sure how long it takes, but it's no bueno.

 

[Obsledpuller]

Low fuel pressure leaves no cushion of fuel between the plunger and the injector tip and can very easily cause tip failure in larger injectors. Ask me how I know :-/ I'm not sure about stock injectors though. Just my personal experience.

 

[ghohouston]

Low fuel pressure leaves no cushion of fuel between the plunger and the injector tip and can very easily cause tip failure in larger injectors. Ask me how I know :-/ I'm not sure about stock injectors though. Just my personal experience.

6.0's have a bad rep for low fuel pressure causing broken nozzles on stock injectors, I'd imagine the same is possible for a stock 7.3

 

[PABowhunter]

I understand how the low fuel pressure is bad for the tips. My truck is definitely not stock. I don't understand how I never noticed a difference in the way the truck ran when the fuel pressure dropped. Other guys said their truck couldn't even hold highway speeds when the pressure dropped

 

[Obsledpuller]

I'm honestly not sure mine ran great when I had 2-3 psi and even 0 at times which is why I originall thought I had a bad gauge found out the hard way it wasn't. Maybe An injector builder can chime in and enlighten us all.

 

[Chvyrkr]

I understand how the low fuel pressure is bad for the tips. My truck is definitely not stock. I don't understand how I never noticed a difference in the way the truck ran when the fuel pressure dropped. Other guys said their truck couldn't even hold highway speeds when the pressure dropped

No idea. Your 01 is close to 1000 pounds heavier than my '97, give or take a few.

You should have had an even more obvious power drop.

 

[boggerr]

Don't know what Irates kit consists of, do you have a pre-pump filter?
I have gone though a few different fuel pumps, they all left me stranded except for the fuelab pump. The injectors can pull the fuel through that pump, it will only be slightly down on power and idle a little different.
Low voltage to the pump will kill it quicker.

 

[PABowhunter]

Yea, it has a pre pump filter. I spoke with Matt from Irate and he helped put my mind at ease about ruining stuff as well as an explanation of why the truck kept running. Basically the injectors kept pulling fuel and the Fuelab pump allows fuel to be drawn through it.

 

[mattman347]

So just to clear it up here, the Fuel lab pump was NOT the issue here but more so a wiring issue. Just don't want people to become "scared" of an aftermarket pump. These fuel lab pumps have proven very reliable for us in all conditions.

 

[PABowhunter]

Thanks Matt. Yea, don't want anyone to get the wrong idea. I was able to troubleshoot the root cause back to the batteries. Fuelab pump has been great.

 

[mattman347]

No problems! If you need anything else just let me know!

 

[TyCorr]

I thought a few years back therecwas a fuel lab pump issue? Im not saying there is now or his pump is one of them. I thought people moved to the aeromotive pump because fuelab was troublesome and the walbro is junk(mine has been totally reliable).

 

[mattman347]

Not that I have been aware of. Been selling the Fuel Lab stuff for more than a few years without issues. Anything can have a problem though, its all mechanical, just have had great luck with these pumps. I know the aeromotive has been a good pump also.

 

[TyCorr]

Not that I have been aware of. Been selling the Fuel Lab stuff for more than a few years without issues. Anything can have a problem though, its all mechanical, just have had great luck with these pumps. I know the aeromotive has been a good pump also.

This might be a rough one but I purchased my fuel system from Irate also. When I purchased it in Sept of 12 jake was only offering the walbro or aeromotive as he was pissed at the fuelab guys. This dudes setup is probably newer so if this is akin to allegations that dp tuner blows up trucks, please disregard

I realize two or three years is eternity in this market. Hell two years ago srp's were the end all hpop LOL

 

[mattman347]

LOL, Jake had a beef with fuel lab because of pricing and delivery time i believe. We have since resolved this and highly recommend their stuff! What are you talking about, the SRP was great...for a while.:fustrate:

 

[PABowhunter]

I bought my system towards the end of 2013. I had asked about the Fuelab vs A1000 and Jake told me then he preferred the Fuelab

 

[Obsledpuller]

I've had both a fuel lab and an a1000 with 450/400's and think they are both great pumps. I don't know about aeromotive but I can tell you I had what I thought was an issue with my fuel lab called them and was taken very good care of! (I later found a wiring issue also)