78 XS1100 Fuel Injection Project

[Prothec]

With Spring approaching, I'm getting back in gear working my '78 rebuild, along with an EFI conversion and GM ignition.

I have collected a few parts over the winter, but obviously have quite a few parts to go.

Parts I have:

MegaSquirt-II PCB3.0 (assembly complete)
2003 GSXR 600 Throttle Bodies w/ injectors and harness
Innovate LC-1 WB Controller w/ O2 sensor


At this point I think the main challenges I am going to have is with locating an appropriate fuel pump and making the induction plate (or having it made) for the GM DIS ignition.

From what I understand, the stock fuel pump specs are as follows:

Internally regulated to 43.5 psi
Flow (GPH): 15.8 (someone approximated on a forum post)

I have been looking for an inline fuel pump and believe I may have found one that will work. Does anyone see a reason this wouldn't work?

Airtex E8445
Pressure: 45-65 PSI
Flow (GPH): 35
Max Current at Shut Off: 7 amps
$78 shipped from Advance Auto Parts after a coupon code (A124)

I contacted Airtex to get the max current draw. They did not have any specs available for current draw at any specific pressure. They of course recommend against using the pump for any motorcycle applications because "The flow may be too great for the fuel system."

The alternative is, of course, to locate a stock GSXR pump and rig up a small aux tank for an in-tank return-less pump, which would also solve fuel supply and return line placement concerns..

Any thoughts?

[DGXSER]

Only suggestion I would give is to review THIS thread, but I see you were around here when this was happening.

[81xsproject]

I have an MSD inline pump I decided not to use on my project. Let me know if you're interested or have any other questions. There is also a really good FI thread on the UK site.

I also made a relay board and have extras. It is very small, fits perfectly in a radioshack project box (2"x3"x1"), and contains all fuses and relays for MS. It REALLY simplifies wiring and includes a trick little circuit for the headlight that keeps it off until you put the bike in gear and keeps it on until the key is turned off.

PS I like your signature. Me too.

[Prothec]

I ran across this link (http://www.madhu.com/content/Main/FuelPumpController), which makes me think going the aux tank and GSXR600 pump route would be the best way, not to mention add a fuel pump controller in the future.

Considering I don't have any welding equipment or experience, or know anyone who welds, I realized today I wouldn't need to weld anything. If 2" diameter pipe is large enough, I have plenty of 2" copper available.

With an intank, internally regulated, pump it now sounds so much easier to implement without a return line.

I think I'm going to move forward with ordering an intank pump and see where that takes me.

PS I like your signature. Me too.

[Prothec]

Can anyone clarify for me how these in-tank pumps are regulated?

For some reason I was thinking the pump itself had some sort of regulator built in, then realized that didn't make much sense. It's the assembly that the pump sits in that has a regulator built in, isn't it?

I will probably order one of these:

http://www.ebay.com/itm/New-Intank-F...31ad88&vxp=mtr

[clcorbin]

Actually, you are sort of correct IF you are talking about a MOTORCYCLE pump (well, most of them at any rate!). Your normal car fuel injection pump works in one of two ways:

1. Pump operates at 100% output and a regulator at the fuel rail diverts the "extra" fuel BACK to the fuel tank to maintain pressure.
2. The PCM electronically controls fuel pressure directly by regulating the fuel pumps speed by varying the voltage at the pump with PCM.

Most bikes work a bit different. They have a regulator built right into the base of the pump that dumps the extra fuel right back into the fuel tank (the fuel never leaves the tank). The pros for this is that it is simple and only requires a single fuel line to the throttle bodies without also requiring a fuel pump management unit. The cons are that it maintains a constant pressure relative to atmospheric pressure and NOT relative to the intake manifold pressure the way a car does. Constant delta P at the injector tip simplifies the fuel delivery calculations a lot, but it can be got around if you know the manifold pressure and the desired fuel flow rates.

Can anyone clarify for me how these in-tank pumps are regulated?

For some reason I was thinking the pump itself had some sort of regulator built in, then realized that didn't make much sense. It's the assembly that the pump sits in that has a regulator built in, isn't it?

I will probably order one of these:

http://www.ebay.com/itm/New-Intank-F...31ad88&vxp=mtr

[clcorbin]

I just took a look at the ebay listing. If you scroll down a bit, you will see the fuel pump assembly that comes on the GSXR600. You will need that whole thing to make it work the same way it does on Gixxer.

So yes, that whole ASSEMBLY contains the fuel pressure regulator. In my first post, I was referring to the what thing as the fuel pump (actually, that is the first listing I have seen where you can buy just the fuel pump and not the assembly for those things)

[Prothec]

Thanks for the info, Clint.

It sounds like no matter how I look at it, I will be adding a return line. I plan to run a T at the rail, one side being the return line with regulator, the other side going to the fuel rail..