MAKIN'SMOKE

Looking for some help with this problem. I recently installed the FASS 95/150 on my truck it had the factory updated (yeah right) intank lift pump previously. Followed the FASS instructions to a tee. 1. removed factory feed line and clip. 2. intalled fass 3/8 hose with new quick coupler to tank. 3. removed factory banjo fitting on vp44 and installed the the supplied crossover and 90 fitting to vp44. Unplugged old lift pump connection and plugged in FASS connection and took the time to properly prime FASS system , good returns at filler neck return truck started no problem. pump is running whenever truck is running correct? Factory fuel filter is now out of the loop correct? When I installed the FASS the fuel gauge was reading just about full. Took truck for a test drive stopping every once in a while to make sure FASS was still running it was. All was good. Went out of town to work truck was readiing just over half a tank of fuel when all of a sudden it surged a couple of times and quit. When I went to reprime the system it sounded as though it was just pushing air no fuel, screwed of filter and no fuel. put 10 gallons of fuel back in reprimed and truck started. drove again for a while till truck was reading just over half and she dies again same scenario. What gives ? is the intank pump somehow blocking fuel to the FASS whenever tank is at half or less? Any insight or soutions would be greatly appreciated. I just bought a fuel pressure gauge but wanted to hear what you guys have to say before installing it. Should I run the factory pump in conjunction with the FASS. Help on this would be greatly appreciated. Thanks in advance.

Diesel-Dan

You can not draw through the intank pump. You need to find a stock sending unit or install a draw tube in the tank (STK-1001). The intank pump is a major restriction as you found out. This is a hit and miss issue with alot of truck on the road.....some dont even know they have the intank pump installed when they go to install our system.

TorqueJunkie

I bought a stock sending unit off of Ebay for about $50.00 shipped when I did mine.

fiveology

Had the same problem with mine, you need a stock (non in-tank pump) sending unit. The FASS will not suck through the in-tank pump.

MAKIN'SMOKE

So to replace the sending unit do I just unscrew the old one from the top of the tank and put the new one in?

badme

I had this same problem with my truck. I also have an 01, the problem was the sending unit failed at the half full mark. My aftermarket lift pump would pump air when the guage said 1/2 full, it had a air leak at the crimp for the fuel pump, where the line is crimped on. I bought a new sending unit from chrysler, the new ones do not have a pump on them and look much better built than the one I took out. Lucky for me my girlfriend works at a Jeep dealer and I got mine at cost.

badme

Oh yea, I almost forgot. Mine took out the VP44 too. Lucky for me it was covered under warrenty. The fuel guage never went under 16lbs even when it was pumping air.

Diesel-Dan

Did this work?

MAKIN'SMOKE

Thanks for checking back Dan I hooked the stock lift pump back up so it would feed The FASS seems to be working good. No less than 12 psi now Is this ok to do?

Diesel-Dan

UM.....well......we never tested it and that pressure is rather low for a FASS and Stock pump stacked to be honest.

Bottom Line: I don't suggest it. What you have going on is a lower GPH pump feeding a Higher GPH pump that is a return by-pass style (FASS ONLY.....HPFP is internaly regulated). Granted this is better than trying to pull though a dead pump. BUT this may still cause the FASS to cavitate. Our pumps were not designed to run with positive head pressure on the suction side. It has a check ball under the T-Block that can become disloged with pressure and put the FASS pump into a by-pass. I would drop the tank and install a suction tube kit of your choice very soon!