elec tech

I just installed a new FASS 150/95 system on my 2001.5 2500 4x4. I hooked the fuel line from the FASS into the old filter instead of the injector pump so my FP gauge would still work . I replaced the original filter with a new one, but after bleeding the sytem, I got 12 psi at idle and wot. Thought things were going well but next time I used the truck after starting it the fuel pressure was 5psi, let it idle for a minute and no change. Shut truck off and fuel pressure went up to 6 psi started truck back up and pressure went to 12 and stayed their, idle or wot.
It has done this almost every time I use the truck. I have to start it let it run for a alittle while, then shut it off and restart it to get proper pressure. Have let it run for several minutes (scary @ 5 psi) but pressure will not rise until I shut it off and restart it. This problem was happening to the original pump but it would take 2 or 3 starts to get it to pump up pressure. (but wot with the original pump was 8 psi so it needed replaced anyway) Anybody got any ideas???

nitrousn

Is your guage electric or mechanical? I would verify pressure with a known good guage for a comparison and go from there.

Geico266

Ditto. I don't believe the FP pump is the problem.

Loose the isolator now if you have one. Buy a cheap guage and hook it up to verify readings.

elec tech

Thanks Guys
Will check this weekend!

elec tech

gauge is mechanical with an isolator

nitrousn

They are known to fail. Also if the isolation fluid weeps out a bit the guage will drop in pressure reading. Autometer can tell you how to refill the isolation line if thats the problem.

Geico266

Take the isolator out, fill it with the proper fluid, put in a vise and close vise until fluid drips on floor, turn 3 full turns more. Remove from vise, lay on concrete, smack with 3 pound hammer until you can't recognize it as an isolator. Drop into bottom of the trash can, take trash to curb. Forget some moron salesman ever sold you the isolator.

You have already wasted time, money, energy, and more than likey replaced your perfectly (almost) stock LP to the tune of about $600?

Don't you think this isolator has done enough for you? Loose it!

elec tech

I wish I had only wasted $370 , I got the FASS system not just the pump

elec tech

Hey Geico266
Sounds like a lot of cleanup after your method of adjusting a isolator

Geico266

You may need a few bandaids also.

Geico266

You'll be glad you did. The stock set up is weak at best. You know your fuel is clean, no air, and you are ready for many other upgrades. Good call.

RowJ

Yup! Only thing you wasted was time messing with an isolator. I know no member that has had a fuel leak in their cab from running without one.... if the gauge line is installed properly. Just put a needle valve inline to the gauge. Can shut it down if leaks and also close it partially to prevent needle vibration from too much pressure.

Inexpensive lesson learned as CTD lessons go.

Good luck

RJ

Diesel-Dan

You know how much better my life would be if no one used isolators?

Bleed the isolator. You have air in the line somewhere. Or do as instructed above!

NavyChief

I have the FASS(with all bells and whistles) no wasted money there, and I ditched my isolator long before I got the FASS. Those isolators are more of a headache than they are ever worth.

elec tech

Thanks for all the help, it was the isolator, 15psi with no isolator, where do you get the needle valve everyone talks about?

We need to do a pole "How far can you throw an isolator?"

After the time and money mine made it quite a ways!!

Thanks again for all the help!