Engine/Transmission (1994 - 1998) FASS installed on 12 Valve

[SilverSage]

I installed a new (carter) lift pump, she fired 2 X, ran for a few minutes then gagged and died! Could not get her to start after that so I had her towed to a local repair shop where they diagnosed 0 fuel pressure out of lift pump and recommended a FASS. I figured constant positive fuel pressure would be a good thing so I went for it.



Here were a few surprises I got.



When the service writer asked if I wanted the Prime Lock fuel filter relocation kit removed I assumed that he meant to completely bypass the CTD fuel/water separator since FASS already has a filter and a fuel/water separator. Instead they put the CTD back in its original location; you know the one that’s near impossible to reach. So now I have 3 filters total in my fuel system.



I asked the service writer if they would bypass the mechanical lift pump citing that I would make plate to replace pump and hold the Preheater/strainer in place. He said they would bypass the existing pump. In fact they went through the original pump, so now I have 2 pumps (one that produces 0 pressure on its own). Seems like just another place to develop a fuel leak.



I got enough black smoke to clear bugs out of city block so I turned starwheel all the way down and got back to something that would pass state inspection. Still have good pickup off the line.



The up side is that the truck runs strong. My impression is that the FASS is really overkill on a 12 valve. I would like to her some comments from others who have a FASS or not.

 

[TReed]

I put the high pressure 45psi FASS for 12v on, and bypassed everything. Goes straight from FASS to P7100 pump. I like it so far I put different overflow valve in. I like it besides pump is very loud. Alot easier to change fuel filter and really opens up driver side of engine with everything gone.



Travis

 

[Cooker]

Something seems a little sketchy to me about the shop that did your install.

 

[bmoeller]

Did they ever check the overflow valve? That is what regulates the fuel pressure. And what if the new pump was sucking air? Can't pump much/any fuel when that happens.



Seems like they really wanted to sell a FASS. And, why not remove the old setup? Goofy.

 

[SilverSage]

Something seems a little sketchy to me about the shop that did your install.

Hi Cooker,



I did have a shop do the install but I would not say what shop as that would be considered mud slinging (we can’t have that in America) ((I would be happy to converse in a private e-mail)). I did all I could and needed a “warranty related service” needed to be performed so I had the truck towed and work done including the required warranty related work. I really wanted to get other members ideas and experiences on lift pumps and FASS (with 12 valves).



Often, hindsight is much better and clearer than foresight, in this case I wanted to share my experience with other members and get their opinions. I think that a FASS is way overkill on a 12 valve, but it might not hurt either. The thing that surprised me most is that I had to turn the star-wheel all the way down to control smoke but still I get good drivability, and that must be a good thing. Does this mean the higher/smother input fuel pressure to the P7100 is better?? Also, should I try to bypass the mechanical pump; it is supposedly in the loop to control incoming pressure to the P7100.

 

[SilverSage]

Did they ever check the overflow valve? That is what regulates the fuel pressure. And what if the new pump was sucking air? Can't pump much/any fuel when that happens.



Seems like they really wanted to sell a FASS. And, why not remove the old setup? Goofy.

Hey Bmoller,



I did ask the shop if every thing else checked out and they said it did, (I replaced the overflow valve last year) they also said the P7100 injection pump was probably also toast because of low pressure from the lift pump (supposedly a bad lift pump will burn out the P7100, I purchase this truck because of the P7100). They wanted to get good pressure to the injection pump first to say for sure. They did not remove the old pump because the install instructions said not to but why not the now extra filter? Ideas/suggestions??

 

[SilverSage]

I put the high pressure 45psi FASS for 12v on, and bypassed everything. Goes straight from FASS to P7100 pump. I like it so far I put different overflow valve in. I like it besides pump is very loud. Alot easier to change fuel filter and really opens up driver side of engine with everything gone.



Travis

Good to hear TReed, do you have a part number for the overflow valve?? any tips for making the changes?? What do I do t the stock filter??

 

[zstroken]

Just put a regulator on the return side of the pump, then you won't buy another overflow valve, plus you have adjustable pressure. I too am running a fass on a 12V the hight pressure unit is noiser than the 150 GPH, but for most the 150 GPH unit should suffice.

 

[SilverSage]

Just put a regulator on the return side of the pump, then you won't buy another overflow valve, plus you have adjustable pressure. I too am running a fass on a 12V the hight pressure unit is noiser than the 150 GPH, but for most the 150 GPH unit should suffice.

Which regulator did you use??

 

[zstroken]

I don't have a part number, but it was an aeromotive regulator. I am sure you could find a cheaper one.

 

[TReed]

I just used a schied overflow valve, not sure what its set at. I got rid of the stock filter, heater, and lift pump and have a block off plate where lift pump used to be. Mines seems to be working great this way.



Travis

 

[LowFly]

Just put a regulator on the return side of the pump, then you won't buy another overflow valve, plus you have adjustable pressure. I too am running a fass on a 12V the hight pressure unit is noiser than the 150 GPH, but for most the 150 GPH unit should suffice.

Rember that the 150 GPH unit is only good for about 30 PSI or motor life will be reduced due to running over max motor amperage. The 200 GPH max pressure is 80 PSI. When adjusting pressure, always check for return flow. you need some flow for the FASS to work properly.

 

[zstroken]

SO lets say I have a 200 GPH unit and it is set at the stock 45PSI, and I have regulator on the return line of my p7100 set at 30, what won't work properly on the Fass??

 

[LowFly]

SO lets say I have a 200 GPH unit and it is set at the stock 45PSI, and I have regulator on the return line of my p7100 set at 30, what won't work properly on the Fass??

Nothing... ... the P-7100 is the restriction... . im talking about the return line back to the tank from the FASS. If you get that too tight, the FASS wont work... . i might have misunderstood your first statement.

 

[zstroken]

LOL, yea different pump.

 

[LowFly]

LOL, yea different pump.

Im going home... its late and its been a LONG BAD DAY!!!

 

[JPittinger]

... they also said the P7100 injection pump was probably also toast because of low pressure from the lift pump (supposedly a bad lift pump will burn out the P7100, I purchase this truck because of the P7100). They wanted to get good pressure to the injection pump first to say for sure.

Wow, you're gettin' screwed! Next they'll sell you a stock P7100 for $6k (plus install, of course).



The bad lift pump on a 12'er won't hurt the inj. pump. Tell them to go back to 24 valves and quit blowin smoke back up your tailpipe. While you're at it, let the rest of us know who these jokers are so we don't spend any of our hard earned $$ there.

 

[tp0d]

I agree with JPittinger... The second I heard this from the mechanic, I would have left.



I would take the truck back and have them remove the redundant filters, and also take out the old lift pump from the circuit. It certainly is not needed to 'slow' flow to the P7100, the overflow valve will take care of that. The extra flow restriction will cause undue wear on the FASS pump motor, and it will fail prematurely.



I dont know about you, but I wouldnt have too much faith in the shop you went to. They have a nice piece of wool, and its goin right on your head. Sorry to say.



-j

 

[Stroker Smoker]

Originally posted by SilverSage

Also, should I try to bypass the mechanical pump; it is supposedly in the loop to control incoming pressure to the P7100.

I would bypass the mechanical lift pump. I have seen it when someone would install an electric fuel pump in a car, not bypassing anything else. The bad stuff happens when the diaphragm in the old mechanical fuel pump tears and will allow the crank case to fill with fuel, toasting the engine.



Phill

 

[Joe G.]

SilverSage,



You probably had an air leak that caused the zero pressure from the mechanical lift pump. It will NOT pump air. That would have been cheap to fix. The shop just plain robbed you. My stock fuel supply system runs over 40 PSI on the road all the time since I replaced the overflow valve with a new one from TST Products. My lift pump has 243K miles on it.