My fuel pressure has been really low lately, like between 0 and 3 psi. But, whenever it is cold outside, my fuel pressure is up, around 6-7. I changed my lift pump out with another stock filter cannister mounted pump, and I have gotten the exact same readings. There has been some noise coming from around my fuel pump, so I am wondering if it is going out. Also, when I accelerate, my fuel pressure sometimes goes up 1-2 psi, when it should be going down right?

Any ideas? I am lost. It has been doing it for a couple months now and I cant figure it out. I want to get a GDP GFS-392, but dont really have the money to spend right now, unless I truly need a new lift pump, I will buy it.

The truck runs fine, starts fine and everything. I kinda think I have noticed a slight decrease in performance and fuel economy, but who knows. Maybe the fp sender on my Commander is bad? Thanks for any help, since i have no idea.

M Sandt

 

I had the same issues not too long ago. I bit the bullet and installed the GDP Fuel Boss mechanical FP and I am glad I did so. I was running 6-7 PSI at idle and it would drop to ZERO when I accelerated (not good with a Smarty installed).

Now I am running a consistent 16-17 PSI and it has only dropped when I had some heating of the fuel on a long run out of San Antonio at 85 MPH. I thought the FP sending unit might have been bad too, but that turned out not to be the issue.

As for replacing the stock FP with another stock one, I would suggest spending the extra $$ and getting either a Walbro or mechanical set-up. You won't be disappointed either way.

 

I need to call Quad because my second sending unit went out. Check your pressure with a mechanical gauge before blaming the pump.

 

Do you have any idea where I could temporarily get a mechanical FP gauge to check my pressure?
I have been really wanting a GDP Walbro, and the reason I thought it might be the sender is because when I replaced my pump a month or so ago with another (used)stocker, it gave the exact same readings as my original did, which I thought was a little unlikely. I wont mind getting the GDP because I will know for sure I am getting pressure, but dont neccessarrily want to spend the money right now. I think I might just say what the heck, and order one today. I saw on them on DTR for $409, anyone see one anywhere else cheaper? I thought that that was a pretty good price. How is their shipping? Also, how bad are they to install? How long does it take? Thanks again guys.

M Sandt

 

Here's what I experienced:

1) Installed Commander, FP sending unit, Smarty, etc. No problems with install, but FP was never over 9 PSI. Ran for awhile, had a buddy check it out and he said "Holy Crap! You need a fuel pump NOW."

2) Installed the Fuel Boss after talking with Richard. Shipping was fast and good packaging. Installation took about 3 hours mainly due to the press on fittings and the climbing in and out from under the truck.

3) After installation, noticed FP going to 17 PSI - awesome! Then it dropped like a stone to 6 PSI and never regained. I had to siphon the fuel to the pump (Richard talked me through all of this on a Sat. afternoon) and pressure came back and stayed - - for awhile.

4) 2 days later, driving around on the hwy at 85 MPH or so for about 35 miles, go to exit and FP drops to 0 ! ! ! Shut the truck down, waited for about 5 minutes while talking to Richard again, and started back up. FP came back up.

So why the long discussion: I determined that I had some residual air in the system that fooled the FP sending unit. I have NEVER had that happen again since that day. I have disengaged my stock FP harness and will only run with it when I change fuel filters.

Hope this helps. I can honestly say that Richard at GDP is a great help and will assist with any questions. Great guy, very responsive and puts out a great product.