Ok my I was crusing down the Interstate this moring and the fuel pressure gauge while going 70mph... would go from the normal 10psi down to 5psi and then back up and then back down.. you get the picture.. Has never done this before..

Is this a sign of the pump starting to give out or is this a new one to all? Ideas?


Matt W

 

Hello xj2extreme and welcome to the site.
Ok first you need to fill in your signature with the specs on your truck. Including any mods so those who know that model of truck can help.
Also what type of gauge do you have (Electric or manual)?

 

sorry bout that.. the gauge is a manual, DiPricol reading off the the schrader valve on the fuel fillter housing, it is running a inline isolator also from Dipricol. (was all in the kit together).

 

Hey xj2extreme, I have the Dipricol Fp guage with inline isolator also and I had the same problem you describe. I thought it was the lift pump so I changed it out and pressure is back to normal. I've been reading posts lately about this possibly being an isolator problem or a lift pump wire conector problem. I just hope I didn't change the last lift pump if it was still good. In my case, I guess it was either the conection or the lift pump and not the isolator because after the change it was all fine. I just don't know. If it wasn't the pump, at least I have a good replacement pump now.

 

There are a couple of guys here that had problems with the isolators but I don't remember what it was. Some of them might be by to help you out on that. You can do a search using the search link at the top of the page on isolators and find those threads.
Good luck

 

First thing I'd do is clean all the wiring connections to the Lift Pump, coat them with dielectric grease and road test again.