Keyser

Where am I supposed to tap into the fuel system on a 98 12v? Everything I have seen so far involves tapping a bolt on the IP and don't want to do that. Is there an alternative? Can i run it off of the clean side of the filter on top of the filter?

OldDodgeOwner

yeah, you can put it on top of the filter, I don't remember which port to hook to though

infidel

The threads on top of the 12 valve filter are metric bolt size, you need an adaptor like this one http://www.tstproducts.com/index.asp...PROD&ProdID=62

It says not for permanent hook up and I can see why, seems to me engine vibration could easily break it.
Tapping the inlet banjo bolt is no big deal, much easier than tapping for a pyro. By far the best way to do it.
More info https://www.dieseltruckresource.com/...41&postcount=9

Dartmouth 12V

Yes tapping the inlet banjo bolt is the way to go. You can get it pretty well lined up by drilling down through the center of the bolt and then tapping from the other side.

Keyser

I wanted to avoid that, but if that the way to go i'll try it. Do you need a needle valve with an isolator? I Found needle valves in town and I am going to get one after work if I need one.

bob4x4

If you don't want to tap you can also go to miller tool and look for the pressure test adapter it is a bit beefier.

infidel

Just a needle valve will do. Run the valve barely cracked open.

Keyser

I already had an isolator so I used it. The needle valves in town are of no use to me. They don't hook up to any of the other tubing I have. The gauges pulses at idle, but not when your into it. Does this mean I need an isolator and a needle valve? I don't really want fuel in the cab.

Dartmouth 12V

The isolator that you have takes care of keeping the fuel out of the cab. The needle valve besically chokes the flow to the isolator down so much that the pressure doesn't fluctuate with each time the lift pump pulses. You should add either a needle valve or a snubber(does the same thing but not adjustable), to get rid of the pulses or your gauge will wear out. I installed mine initially without a valve and was shocked to see how much everything was pulsing under the hood before I added a snubber. I really thought a fitting was going to blow pretty quick with that extreme of pulses.

Keyser

i finally got everything in and something is messed up. When i first installed it it would run at 20 and change depending on if i was into it or not. Then it went to 15 then 12 then ten and now its at 5 psi. it no longer swings with the throttle it just stays put. any idea what is going on? What do i check next?

patdaly

Fuel filter first.

Keyser

i replaced the fuel filter not long ago. the filter that was in it was black so after i changed it i changed it again a few months later and that one was still good so I doubt thats it. I am wanting to blame the gauge for dying.

infidel

Sounds like the needle valve might be closed down a hair too much.