I read the thread on a Fast 2.0 going in, but I'm using a FAST without timing control, and my OEM harness is still intact.
So here's the issue. I'm not exactly a bigbrain with electronics. I know that when I hook up the Fast system I can lose the injector plugs/wires back to the firewall. The same goes for the IAC, MAF, Throttle Position Switch, and Knock Sensor.
I'll leave the water temp so I get a reading on the dash. Same for the oil pressure and temp.
My plan for the fuel pump is to somehow bypass the OEM computer and use it thru the FAST. I don't think the fuel level goes thru the ECM so I'm thinking it'll be ok.

The best help I remember getting has been thru you guys, so whaddya think? I know I'm gonna need advice here, so thanks in advance.....

IIRC, you have an 87, right?

Assuming that...

I think you will be ok. Fuel level is not something the ECM cares about. It is strictly for us humans to measure.

You will lose MPG measures, because the fuel flow will no longer be monitored by the ECM.

Be sure to seal the ends of the wires, so they don't corrode... that could lead to odd behaviour from the ECM and/or failure.

Water temp... there are two sensors, one for the engine, one for the dash. I suspect the one for the engine is the one that will be needed by FAST.

Oil Pressure goes to the dash, not the ECM. There is an oil pressure switch that will keep the engine running if the fuel relay fails. But it will NOT shut down the engine if there is a loss in oil pressure.

that's all I gots for now!

Thanks for the reply, Andy.
Actually, the car is an '89. The '86 I had for a year or so got sold to make room for the '89.
Ok, so if my '89 is similar to your description of '87, then where do I find each of the sensors? I know only of the water temp sensor in the right side head, and the oil sensor behind the dizzy. Is the other oil sensor down near the filter location?

The oil sensor at the filter is for oil temp.
The sensor behind the distributor is for oil pressure at the gage, and for the fuel pump power after the initial first prime. It's a dual function switch.

Joel

There is a coolant sensor on the front of the intake, near the gooseneck.

Thanks Andy for the reminder of that front coolant sensor. Which is which of the two? Any idea? Do they go to just the dash, or the ECM, or one of each? On second thought, if I'm not mistaken, the front water temp sensor probably goes to the ECM, and the simple connector on the head probably goes to the dash?

Joel, do those two oil sensors, one goes to the dash and, presumably, to the ECM. So I guess I'll need to pick up power to send to the fuel pump AFTER the ECM so the fast unit can run it.
I think I need to digest this a while, I might be sounding a bit out of whack on this.
Thanks again for the help to BOTH of you, please keep it coming, and I'll strap on the old thinking cap so I can get it straight.

Quote:

I know nothing about the FAST system, can't help on that. This link is a fairly decent description of the fuel pump power source.

Joel

http://forums.superchevy.com/corvette ... system-for-1989-corvette/

oil data does NOT go to the ECM. It's strictly info for the driver.

Coolant temp is much more accurate in managing engine operation, because it changes more rapidly than oil temp.

And yes, the temp sensor on the front of the manifold is for the ECM, the one on the head is for the display.

So far, here's where I'm at. (And don't be afraid to correct me on this)
I think I'm gonna leave both oil and water sensors alone. I don't wanna lose any more dash info than I have to. And there's another consideration for this, and that's if the water temp can turn on the cooling fans, and/or if either is needed to work with the heat/ac.

My service engine soon light will always be on unless it's possible to wire it into the FAST unit. Otherwise I'll have to pull that bulb out.

I printed off the article that JoelD gave us a link for. And it IS very informative. But looking at the diagram supplied in that article, I think it's for a 5.0liter F-body. But the article is no less informative and I still thank Joel for the very good link.

I'm still not sure where to power the fuel pump from. I can't find a diagram on FAST's website for my unit (#302000)
but I think the unit will run the pump. Obviously the FAST unit has a set of instructions with it, but if I can run down a set without tearing into the box prematurely, I'd like to do that instead. I just need to figure out where to go into the OEM harness to run the fuel pump without causing any other cans-o-worms to open.

That's all I have for now. Thanks guys.

Well, I spent these last two days out in the cave working on the Vette. Nothing too important, but just some stuff to do since the engine is out.

Andy, you mentioned sealing off the wires. My thoughts were to trace them back and actually remove them from the bulkhead connector, IF that's an advisable option.

Any thoughts on this?

Quote:

Having worked on a truck with a non-original brand engine in it many moons ago, my suggestion is leave the wiring in it for now. Unhook and mark each wire but leave it intact till such time as you get everything worked out. Once it's all good then you can start removing wires if that's your desire. Better to have them around in case it turns out one happens to be required and if you've removed it then it's a lot of extra work to undo it.

My 2 cents.

That's a pretty good two cents worth!