I just redid my fuel lines after suspecting a leak. I have noticed two things after replacing my fuel lines. Before when I turned off my truck the fuel pressure dropped almost immediately. Now it takes about 10-15 seconds for it do drop to zero. Secondly and more surprisingly my fuel pressure is now a little lower. Was running about 11 psi at idle and now it runs about 9 psi. I am thinking I may have knocked some gunk loose and clogged my fuel filter which is past due for replacement anyway.

Could anyone else tell me how their fuel pressure drops after they shut down their truck? If it matters all my lines are 3/8" with Aeroquip -6AN fittings.

 

Do you have a needle valve in line with the gage? Having it too tight will cause the gage to drop slowly and probably not read high enough.

 

No I don't. At least not that I know of.

Keith

 

Check the line from the gage to where it connects with the fuel line. The previous owner may have put one in. Also, it might be a kink in the line or something may have gotton into the line. Or, maybe a bad gage.

 

The line might be smaller than the other one, and would cause it to be a little lower in pressure. I had to put in t-fitting for my fuel line and fuel pressure sensor and the inside of the fitting restricts it so i only get up to 15psi with a FASS fuel pump. After the truck shuts off the pressure reads at 1psi.

 

Oddly enough after driving it for a while longer everything settled back to normal. It now drops immediately at shutdown and pressure is back up to almost 12 psi at idle. I guess maybe there was some air still in the fuel system somewhere or something.

I am thinking about putting two lift pumps in line with each other. If I do this do I need a larger return line or is the factory one just fine?

Keith

 

I think several people on here run two pumps. Just be sure that if one fails, it will still allow fuel to pass through to the good one. I don't think a larger return would be necessary since both are pumping the same volume.

I'm sure someone with a dual pump setup will chime in here at some point.