Here I am

FASS is finally out for good.

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Vendor question

12v High HP fuel system?

My P7100 is hating the low fuel pressure and 100 degree days so I finally bit the bullet and bought the rest of the parts for a new fuel system. I just unbolted the FASS , drained it and put it in a box. Installing an A1000 pump and regulator. 5/8" lines, bulkhead fitting for new suction line, and a pair of big canister filters. Hope that 35 to 40 psi pressure and high volume will help make up for trying to squirt fuel through those little holes.
 
Ron, you might want to run a voltage step down for that pump then have a switch to turn on full power, I run one on my truck as a aux setup and it gives me another 25 psi and a bunch more volume for full power runs, it goes from the pump up to a Y then to two inlets in the pump!



How does your go into the pump?



Jim
 
This pump has a single inlet. I am trying to see if running more fuel through the pump will correct a problem I am having. If it doesn't, Piers has another pump built for me to try. I called to see if they could make it dual inlet, but I was a little late and the pump was already out of the shop. The consensus seems to be that there is extra strain and heat caused by trying to squeeze fuel through the little holes in the 24 valve injectors. So it starts running rough when it gets hot. At least that is my understanding of it.

Ron
 
Jim Fulmer said:
Ron, you might want to run a voltage step down for that pump then have a switch to turn on full power, I run one on my truck as a aux setup and it gives me another 25 psi and a bunch more volume for full power runs, it goes from the pump up to a Y then to two inlets in the pump!



How does your go into the pump?



Jim





Make sure it's a PWM if you step down. A simple reduction in voltage will be bad for the pump, based on my discussion with Aeromotive.



They sell an overpriced dohickey that can PWM any pump down to almost any level. They market it as "an automatic tranmission for your fuel pump".



www.aeromotiveinc.com
 
Of course hind sight is 20/20... but a mechanical fuel pump capable cam would have been a nice addition when making the swap.
 
When I got my cam I ordered one with a lobe to drive a mechanical pump. I also have the mechanical pump. But I was having this problem with 24 lbs of fuel pressure from my old FASS unit. The mechanical puts out around 20-24lbs at idle. I need to try a little more and see if it helps. The fuel pump is cheap compared to another injection pump, so I bought one that would put out enough to answer the question," Is my rough idle related to low fuel pressure?" If this doesn't fix it, it will be time for p7100 number 3.
 
Been running with the 12 valve style mechanical pump now for 2 days. Can't tell any difference except it starts instantly with the mechanical and has always gone a rev or two before starting with the electric pumps. Bummer is the idle is still not great in hot weather. Hasn't been missing yet. I have to deliver to SF tomorrow afternoon with the trailer. Will be interesting to see if it is any better in traffic.
 
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