Upgrade Fuel Injection

[Apex Man]

I have an MSD inline fuel pump that I will upgrade my fuel injection system with. After looking at the wiring diagrams I noticed that there is a suppressor (diode) across the pump relay's coil. I realize this is to protect the output stage of the ECU from collapsing magnetic fields causing CEMF spikes. This makes me wonder if the ECU is "cycling" the pump on and off as needed. I did not see a pressure transducer or switch so maybe the ECU pulses the pump until high flow is needed determined by maybe the throttle position, air sensor, etc. I have mine apart right now so I can't check this out so I was wondering if someone else has checked into this. I need to know so I can determine whether or not to use the MSD pump as "constant duty" stand alone pump or trigger it with stock pump's signal in a booster arrangement. "It's the little things that bug me".

 

[1CrazySledder]

Keep us posted on your results. When I go to 10lbs or higher, I may use the same as you. Which fuel pump is this, have a picture or something? I'm not even sure which fuel pump to go with when I do upgrade. I have researched that yet.

Thanks,

-Vince

 

[kinger]

Is the apex a returnless system or does it have line going back to the fuel tank after it goes through the rail? That should tell you.

 

[aja636]

There is a return line coming from the rail to the tank. With a CPR turbo kit they give you a bigger fuel pump that you use in place of the stock pump. All I did was hook up the wires from the stock pump to the new pump. It still cycles and shuts off when there is pressure.

 

[Need for Speed 2]

the original pump does cycle in and out but i found that running 2 pumps at once made my mcx turbo sled run pig rich. i solved the problem by running the msd pump off a hobb switch set to 12lbs of boost reference point .run power through a relay. worked great af.s ran consistant. i would not run 2 pumps together i feel fuel volume exceeds return systems flow capacity and from there pressure increases out of control. my experience im sure some of the keyboard racers will chime in and have a problem with my solution but couldnt resist this topic ,.hope it is some use. have a good one.

 

[HAMMER]

I think I'm going to try a fuel pump booster. At 8000ft elevation, with my supercharger maxed out at 150,000rpm, it is making 8lbs boost, and the stock fuel system can handle it without issue. I added a 30-shot of nitrous, which causes the air fuel ratio to slowly creep lean during an 8-10 second run, even with fuel controller set to an overly rich off-nitrous setting. I know it's because fuel pressure is tapering off as demand is increasing. I want to set up for a 60-shot this season and wire the fuel pump booster to activate when the nitrous is activated. This would cure the slow lean creep I'm getting and would maintain a consistent fuel pressure (it can also be set for boost activation). I sent an email with questions to Kenne Bell on the dimensions of the unit and attached fuel/dyno data but have not received a response from them at this time.

The unit is $219.00

---------------------------Boost-A-Pump----------------------------
http://www.kennebell.net/accessories/bo ... tapump.htm


---------------------------Magazine Articles-------------------------
http://www.kennebell.net/media/articles/FUELPUMP.pdf

http://www.kennebell.net/media/articles ... t_Pump.pdf

http://www.kennebell.net/media/articles ... ENSICS.pdf

 

[mulot30th]

BAP is a great product, we run this on our supercharged 2002 transam with a walbro gss340 fuel pump and it will boost effective pump capacity up to 40-50%...

 

[HAMMER]

Spent all day google searching "import tuner" sites and high-performance magazine articles.

In an automotive application were environmental factors and installation space is not as critical a factor Boost-A-Pumps (step-up transformers) look like the best option.

Most of the highly detailed articles, where actual bench and dyno testing were involved, showed oversized fuel pumps running continuously to cause over rich conditions, fuel overheating, and poor fuel economy. FMUs/FPRs were also shown to be a poor solution. Here’s one example of why.

The relationship between changing the fuel pressure and the amount of fuel delivered is the square root of the ratio of fuel pressure. If fuel pressure is doubled, then about 40 percent more fuel is delivered. To double the fuel delivery, four times the fuel pressure needs to be used. But that's only possible if the pump itself is capable of delivering fuel at that pressure. How much does a Honda fuel pump actually flow? The results may surprise you. A stock '99 Civic Si (B16A) fuel pump flows enough fuel at 35 psi for 400 crank hp. A stock '97 Prelude fuel pump flows enough for 476 crank hp. It's interesting to note that as pressure is increased to 75 psi, such as with a rising rate fuel management unit (FMU), the pump can only flow enough for a little more than 200 hp. If you boost your car, use a rising rate FMU set to rise to 75 psi or higher, and have more than 200 crank hp, then you're in trouble, as you'll probably experience significant leaning. Too much pressure has other disadvantages. Fuel injectors require more current to open, meaning they run hotter and are less reliable as a result. In addition, they can take longer to open, and there's a greater tendency for the fuel to leak past the injector seals.

Since I'm limited on space and will be applying this in environmental extremes it looks like Need-4-Speeds solution is going to work the best for me. I’m going to set it up to activate an in-line booster pump upon nitrous activation and see how that works. If it doesn’t supply enough fuel quick enough for the nitrous application my alternative setup is going to be to activate the in-line booster pump with a 4-psi Hobbs Switch regardless of nitrous activation.

MSD Fuel Pump 2225 (JEGS $94.00)
Hobbs Switch (contact tolerance 3.1 to 7 psi +or-1) Factory set at 4-psi
Honeywell part number 76575 or NAPA part number 701-1575

Does anyone have pictures of where they tapped into/installed an in-line booster pump on the Apex? How they did it? Cautions? Warnings?

 

[Need for Speed 2]

boosterpumps

hammer be cautiouse some pumps wont let fuel to flow through meaning the add on pump can stop fuel flow from the stock pump until the secondary is called up. hope it helps.

 

[HAMMER]

Some pumps won't let fuel to flow through meaning the add on pump can stop fuel flow from the stock pump

Ya, if that's the case, fugg, it figures that it couldn't be that simple !!!

What is the inside diameter of the Apex fuel line ???

More google searching today......found this pic in some Aeromotive instructions.

The bypass loop with check valve to eliminate back-pumping and no issue with back-pumping on the fuel pump as it has an internal check valve.

 

[Need for Speed 2]

thats what i had figured it will work only thing i added a pressure guage in that setup

 

[Srxspec]

What is the inside diameter of the Apex fuel line ???

5/16" (ok actually like .310) measured on the barb from the stock pump.

 

[HAMMER]

Thanks.......
MSD pump has 3/8 inlet and 5/16 outlet.

 

[TWIN TURBO]

HAMMER
I used that Kenny Bell boost-a-pump last year with my stage II SC last year, worked fine but I wasn't pushing it 11 lbs 1000' elev. After all the research it sounded right to me.

aja636
How do you know it's shutting off with pressure? If your listening to it with engine off on initial start up I'm preety sure the ECU has a time-out feature to prime the system on start-up and if it does't see RPM it shuts down. I don't believe there is any pressure reference for the ECU to shut down, that would be the purpose of the bypass pressure regulator on the sled. It will maintain fuel pressure based on the vacumn signal or in the case of our boosted units an increase in pressure.

 

[HAMMER]