When i start the truck I have fuel pressure after about 15 seconds the lift pump shuts off and lose all pressure. I still have the wait to start light coming on i  wanted to check the wire out of the ecm  for power to the pump but I am not sure which wire it is. Any help would be helpful 

Yes. Your still got a electric priming pump because Fuel Boss can't self prime.

Mike and everyone else,

I looked into the fuel boss yesterday.  (thanks for bringing that up!!!!)  I noticed that they went to a bit of trouble keeping the (or a) electric pump in the system.  I don't think this is from a self priming aspect....  Most positive displacement gear pumps have a good Net Positive Suction Head number (NPSH)  The ones I was looking at had easily more than 2' of lift.   BUT....   That is at rated speed.....   While cranking we don't have proper operational speed.  So probably poor lift and poor initial flow rate.   The Fuel Boss designers wanted/ needed that bit of pressure right during starting, because the mechanical pump cannot perform there.

I think this is even more evident based on where the check valve(s) are located.  The only check valve is to keep the electric lift pump flooded with fuel (edit see a bit later in thoughts...).  They do not try and protect either pump from the fact that the other one is on.  (the electric is "shut off" so it doesn't just sit and dead head while the real pump is doing the work.)  (The check valve also prevent "flow" of fuel from the Fuel Boss from running the electric pump backwards when it is off.  I bet this is more the reason for it than keeping the electric pump flooded.....)  So the fuel boss is coming on as the engine starts, working against the pressure of the running electric pump.  This upstream pressure could actually reduce the available NPSH, but the gear pump is strong enough to blow right through that. (Mike this is where it could help with priming if that were necessary, but I don't think it is.) 

I hope this made sense...  I was still fleshing it out as I wrote that.  I think the guys who originally designed it didn't want to have to use the electric pump.  But the mechanical pump, by itself, could be troublesome on some systems that allowed a little bit of air in.  The delay in fuel flow and pressure to the VP during long crank times etc, was just too long for some people (or it caused other problems, again the VP acting as a positive displacement pump has to pull its volume from somewhere.... if air is easy to get that is what it would rather have), so it was easier to use a "jockey" pump (hey it was already there) to cover the low flow and pressures needed during starting, and then bring the big boy on line for the real work. 

I kinda like it...  It is an interesting alternative.  the Jockey pump COULD be a mechanical fuel pump like the older vehicles had....(run from a lobe on the camshaft)(with proper check valves and routing) or just about anything else.. (accumulator?) hmmmmm

Hag

My truck sits unused for weeks at a time. When I start it with the electric "jockey" pump unplugged, it builds operational fuel pressure within 1 second. The reason I run with the electric pump disconnected, the Airtex pump was putting out 16-17 psi and the Fuel Boss at idle will put out any where from 15-18 psi. The two different but almost the same fuel pressures made setting the Hobbs switch (pressure switch) a pain and the electric pump kept cycling on and off very quickly. I read somewhere that people where running the Fuel Boss with the electric pump disconnected or with out an electric pump in the system at all so: I tried it, I like it, and that's all there is to it.       

 

Edited November 21, 20159 yr by IBMobile
double post

DTT Assassin is the other pump just like the Fuel Boss but without a electric primer pump. The only problem is if you have prime issues you would have to pull the belt and use a cordless drill to reprime the system since there is no electric primer pump in that system. 

Another issues that neither Fuel Boss or DTT never solved is distance from the tank. Fuel pumps don't suck very well from long distances. This why everyone was relocating back to the fuel tank making the suction line as short as possible. Then even having Dodge putting the fuel pump in the tank.

1 hour ago, Mopar1973Man said:

Another issues that neither Fuel Boss or DTT never solved is distance from the tank. Fuel pumps don't suck very well from long distances. This why everyone was relocating back to the fuel tank making the suction line as short as possible. Then even having Dodge putting the fuel pump in the tank.

Are the 12v mechanical pumps on the block?  So they are pulling fuel that distance, correct.  Do the 12V have the same fuel pump issues?  I understand that DTT and Fuel Boss are minorities in the market, but I have yet to hear of one failing.  I talked to one guy that had over 150K on one pump.

My fuel boss has been great, but I understand that some people don't like them.  I have heard of people priming them with a drill, not sure I could attach a drill to mine, there isn't much room.  I had some priming issues after I changed my injectors, but the stock-block pump served me well.  I do get a little oil seepage from where it connect to the oil pan, not enough to register on the dip stick, but it is always  there if I wife my finger on in.

2 hours ago, Hawkez said:

Are the 12v mechanical pumps on the block?  So they are pulling fuel that distance, correct.  Do the 12V have the same fuel pump issues?  I understand that DTT and Fuel Boss are minorities in the market, but I have yet to hear of one failing.  I talked to one guy that had over 150K on one pump.

My fuel boss has been great, but I understand that some people don't like them.  I have heard of people priming them with a drill, not sure I could attach a drill to mine, there isn't much room.  I had some priming issues after I changed my injectors, but the stock-block pump served me well.  I do get a little oil seepage from where it connect to the oil pan, not enough to register on the dip stick, but it is always  there if I wife my finger on in.

I believe the 12V pumps were a cam eccentric driven block mounted affair.  They didn't have the issues the 24V had, but that was due to the robustness of the P7100 rather than the cam driven pump.  

12V lift pump had issues with performance.

http://www.torkteknology.com/news/5/Technical-Article-Number-One%252d-The-Cummins-Lift-Pump.html

So with high performance in mind most moved back over to AirDog, FASS or some sort electric lift pump to resolve the high RPM volume loss.

I was looking into the fass pump and I saw this and was wondering if anyone has used there FASS Fuel Systems Diesel Fuel Bulkhead and Suction Tube Kit (STK-1002)

34 minutes ago, catnhat said:

I was looking into the fass pump and I saw this and was wondering if anyone has used there FASS Fuel Systems Diesel Fuel Bulkhead and Suction Tube Kit (STK-1002)

No, but you can do it cheaper.  The below part and a 1-1/8th hole saw and you're done. 

http://www.vulcanperformance.com/ProductDetails.asp?ProductCode=DS2

On 11/21/2015, 8:03:55, Mopar1973Man said:

12V lift pump had issues with performance.

http://www.torkteknology.com/news/5/Technical-Article-Number-One%252d-The-Cummins-Lift-Pump.html

So with high performance in mind most moved back over to AirDog, FASS or some sort electric lift pump to resolve the high RPM volume loss.

With the fuel system designed correctly there are no issues with the stretch from the tank to the pump, with my system the vacuum at the pump hovers around 1-2 in-hg.  Even the stock pre-lift pump fuel system which is somewhat horrendous can make it till 400hp.  With some modifications to the pump and the rest of the fuel system it can support more than what most people need.

Anyhow, the reason I even posted.  The guy in that link fudges numbers and implies inaccurate things.  It's still a good read though if you know what to look out for.

Edited November 30, 20159 yr by Cowboy

ÖGot the fass 150 installed went really good it took about 6 hours over all I am very happy with it. The fuel pressure is little low only at 15 but just drops about a half a pound unlike the raptor .

Do  I have to just put a washer in on the return side? 

One thing that I didn't like was that there is a lot of extra wire the is rolled up under the hood. But I did get the straw cut right I was down the the fuel light.