Sulfur yellow 76: Megasquirted with tbi

[Toehead]

It only puts out 70 PSI max, but the regulator I am running has it at more like 20 psi.

[wingrider]

Well, that is a tad more than the stock carb one, hopefully it flushes it quick!

[socrace]

Had that problem with another vehicle that used an external tank pump. Wound up using a cleanable element filter from Autozone on the input side of the pump and just kept cleaning it, would mostly clog with rust particles.
http://www.autozone.com/fuel-systems/pe ... 52786_0_0/

[Toehead]

That's actually the filter I was using!
It appears to do a fine job with catching even very fine particles.

I replaced it temporarily with a larger metal-can filter from autozone that has a pleated filter with more area. I figure that can hold more contaminants before it clogs.

PS: Thanks for the VE table. That's a good starting point for my bike as well. I tuned the idle unwittingy with the clogged filter, so when I cleaned the filter it basically instantly flooded I appreciate the chance to "reset" back to something that makes a bit more sense!

[82aspy]

http://www.classicgoldwings.com/forum/v ... f=9&t=3089

http://www.classicgoldwings.com/forum/g ... er_id=1836

[Toehead]

Well crap, look at that! I hadn't seen that before!

Thanks for the links.

I'm busy installing an inline fuel gauge so that I can tell when I am having fuel pressure issues... more to come!

[Toehead]

Here is the circuit that I just whipped up to feed the ignition signal to the microsquirt. It will combine the signals from both coils (previously I was pulling a signal off of only one coil). The output should be a nice square wave.

combination.jpg

The fuel filter seems to have quit clogging after a few cleanings.
I had to adjust the fuel pressure to get enough flow out of my injector. I shimmed the FPR spring so that I get 40 PSI at 100 KPA.

One thing I can't figure out is why the throttle body has a FPR that is vacuum referenced when the injector never sees manifold vacuum...

[Toehead]

Tested the circuit on the bike, and it works fine. It allows me to have more flexibility (resolution) in my tach signal.

Now I just need to pot it into a blob of epoxy to keep it safe

[socrace]

That tach circuit looks good. The low voltage of the signal may not get much below 2v, though.
The vacuum referenced fuel pressure regulator was mainly used with tbi to get more fuel at wide open throttle, sort of like a power valve in a Holly carb. So the calibration curve can basically be on/off at something like 4 in hg of vacuum. Although, this mainly applies to big block trucks, so maybe it's different with a Geo Metro..

[Toehead]

Makes sense: It allows you to run a larger injector while still having OK idle pulsewidths

[Toehead]

Potted the tach circuit into a potting box, and it almost looks like I know what I am doing

DSC_0569.JPG

DSC_0570.JPG

DSC_0571.JPG

[desertrefugee]

The output should be a nice square wave.
...

But will the duty cycle allow the pulse duration you need? Won't that be around 10-20% DC?

[Toehead]

The microsquirt triggers on the rising edge of the signal, so even very low duty cycle is enough to trigger. The pulse duration should be as long as the points are open. (or dyna in this case)

I wish I had a scope

[Toehead]

The top end fuel is sorted. I've got the bike pulling until redline.

I also got to witness a "clogged filter" event with my new fuel gauge. It starts with fuel pressure tanking at WOT, then progressively the throttle threshold for 0 pressure gets lower and lower. It must be the pump cavitating.

Cleaning the filter fixes it. Hopefully most of the junk works its way out of the tank soon.

[socrace]

Way to go!
Here is a well rated cheap usb scope (only $60!):
http://www.amazon.com/SainSmart-Portabl ... B00FYGEFYM
I have one similar to this and it works well. Based on an open source design published in Circuit Cellar years ago.