I've got a 7730 ECU thats wired to just control fuel installed on a gen 6 BBC (8.2L). I cleaned and stripped down the entire harness, checked all connectors and wiring, wrote out where all pins go from the ECU and installed the harness in the truck. I have a new O2 sensor and I tested the TPS, CTS and IAT sensors. The ECU gives code 12 when in diagnostic mode and the SES light does not come on until I unpluged the injector connector. I plug it back in and reset the ECU and no codes present again as it should be.

The fuel pump comes on for a two second prime every time the key is set from OFF to RUN and I have new fuel filters and good fuel pressure, on starting the fuel pump stays on.

I have 12V from the injector power wires to ground when the ign is set to run and around 8V when cranking.

I connected my multimeter between the injector power wires and an injector control wire AND STILL HAVE 12V WHEN THE IGN IS SET TO RUN (8V ON START).

If the engine isn't running and the ignition is initially set to RUN, shouldn't I have ZERO volts between the injector power wires and the control wires? Then when the engine is cranking or running the control wires start going to ground with a square wave pulse?

 

A few things required for injector pulse. You need 400 or more rpm cranking speed and drp out of the icm purple/white wire to the 730. You don't state what base bcc you are running $8d but vats will need to be disabled or a hz signal to the ECM.

 

Shorted wire or injector can damage or shut down the injector driver.

 

My ECM is a delphi pn 16198262, which is an OER equivalent to the 730 I think. It has no VATS, VSS, distributor control, EST or transmission wires.

As far as RPM sensing it only has a wire from my TACH on the HEI shared with my tachometer which goes to a small black dongle that has (4) 22-26 gauge wires coming from it: white to the tach signal, red to pin A5, black to ground and pink to D8. Connections are good to / from that thing, I'm guessing its a tach signal conditioner of some sort.

I double checked the injector control wires and they have continuity and are not grounded and terminate to C11 and C12.

The engine cranking speed is 500-600 RPM.

What do you mean by drp, base bcc and $8d?

Its got a custom chip in it so I took a picture of it maybe someone can give me some info on it. Supposedly the engine was using this ECM and harness when it lost oil pressure and spun the #2 main journal bearing so I was expecting it to just work, the only change I made was to lengthen the IAT sensor wires.

 

I can't read your knock board 2nd letter it would need to be p or r or the cylinder select needs to be jumped pin 52 to pin 62 of the memcal. Pin D8 needs the tach signal from the icm. Drp is distributor reference pulse , bcc is broadcast code. the injector driver controls the injectors bye using the ecm/sensor ground.

 

Ok well my setup was used to run the engine...I know this because the harness was covered in mud the same as the engine was. I'm stuck on this point here: When the engine is not turning but the key is in RUN, the voltage potential between the injector power wires (12v ALWAYS in run or start, 0v at off powered directly by ignition circuit) and the injector control wires (C11,C12) should be 0v...I'm getting 12V! This means that the ECM is commanding 100% injector pulse width, or on all the time right? Or does the ECM know the harness is unplugged and closes the circuit?

 

At key-on the injectors are always supplied +12 volts via the INJ1 (& INJ2) fuse(s).

The ECM supplies ground to fire/open the injectors. There is one driver in the ECM, with both pins going to that one driver. So having just a single injector plugged in will show +12 v on the ECM pins.

I haven't tried it, but I wouldn't be surprised to see the same without any injectors plugged in.

RBob.

 

The ECM will ground c11 and c12 to pulse the injectors. I'm not sure what your saying about the injectors being at 100 percent duty cycle. If you are needing to get that much fuel you are max out the injectors at 85 % pw.

 

With the injector connector disconnected, I connected my multimeter to a constant power wire and an injector control wire...I get constant 12V reading which means that the ECM is constantly grounding the control wires even with no distributor signal.

 

If what you said was true you would be asking us why the engine is being hydo-locked with fuel.

A DVM offers nearly no load, you are likely seeing a ground due to leakage in the driver.

RBob.

 

Hmm ok, so I need to load it to test that. I don't have a noid light, would a turn signal light bulb work or will I need something like a 1kohm resistor and an LED? So where do I go from here assuming the injector driver is functional? I know I have a good tach signal going into the black thing which feeds to the distributor HI input signal...how do I test at D8 and what sort of signal should be on that pin? My injectors are mounted to a carb style 900CFM holley flanged TBI and the 4 injectors are paired, each pair is in series...I have no idea if they are supposed to be high impedance or low or what flow rating they have, holley doesn't have a replacement pn and I'm not sure what generation they are either.

 

sounds like you should be using a 747 or 746 ecm.
you can post the ohm reading of the injectors and maybe rbob can assist with the best solution. Have no idea what black box you are talking about icm? tach filter ?
you are using The PnH instead of saturated ?

http://www.dynamicefi.com/InjectorDriving.php

you can use a led and 1k resister to check for injector pulse.

https://www.facebook.com/photo.php?f...type=3&theater

 

If you have something along these lines you can see the injectors pulse.
The signal to d8 was discussed in post #5 .

 

That is the exact one thats on my truck...are those all holleys or did GM make them too?..cuz they have GM sensors and IAC...I bought a holley HPefi full system for my camaro and its very similar with a slightly different injector tower but same configuration.

The little black thing is a tach filter then?

I'll pull off the injectors tonight and test them...one of the first things I was going to test but one step at a time.

 

I found a common part number on the injector plugs: 5719: apparently that is a holley pn 522-80:
Fuel Injector
Fuel Injector Performance Commander 950 Systems 50 PPH@12 PSI 72 PPH@21 PSI

http://www.summitracing.com/parts/hly-522-80/overview/

I tested the resistance on all 4 injectors, all were 1.8 ohm with my leads adding 0.3 to that...so 1.5 ohms which is close to the 1.4 ohms that summit lists.

So resistance is good but WHAT THE **** is on that injector? All four look like that, there is also orange scaly bits inside the injector housings that the filters seem to have stopped. All injector filters look good but what is that crap on my injectors? I cleaned them up about 6 months ago and that stuff wasn't on them.

 

looks like you had a steam engine. I don't think the 730 is a good way to control those injectors that must of had some extensive tuning.

 

What do you mean by steam engine? Whats the best way to clean those? Do you think that junk is why the injectors aren't firing?

 

all that water.

 

The box your speaking of sounds like a tach filter used by Howell in their aftermarket harness designed to be used without ignition. Correct in it conditions the tach signal for the ECM.

That junk in your injectors looks like you flushed dirty lines into the injectors? Do you have filters before and after the fuel pump? One cleans fuel before the pump and one high pressure (finer filter) after pump. Even if one metal high pressure filter after the pump it may have failed, I found 2 metal threaded type Fram fuel line filters, ones used in stock TBI applications to have failed. Shake filter and you can hear the filter rattle inside, it's blown off it's mount inside...

Then you need to figure out if that ECM can fire four TBI injectors? Or if it's possible to mod it to do so? How are the four wires from injectors wired into harness and ECM?

From Holley they fire front two injectors then as throttle opens it starts firing rear two on progressive linkage. Or all four on progressive linkage. One aftermarket AFI GM system I worked on had injectors rewired and firing one front one rear on progressive linkage and rear bores would fill up? Just because this system ran on an engine that blew up does not mean it ever ran right!

 

Well I had new clean lines flushed with gas and installed with a 100 micron pre-filter, walbro pump then 10 micron steel canister filter. Six months before I had the entire TB apart and inspected and cleaned all parts including the injectors and I didn't see that stuff on them but it sat for a while on a shelf.

The injectors are wired in pairs. FR and RL in series, FL and RR in series. Each pair has its own fuse and power wire with an ECM controlled ground wire.

I'm thinking of building a megasquirt system with ignition control if this ECM doesn't work right.

 

So I took my injectors into a diesel injection shop for servicing, only one was repairable the rest wouldn't even open due to corrosion. The TBI injectors are over $100 each, not very cost effective. I guess the humidity over the summer here and my TBI just sitting in a box took its toll on those injectors!

 

I don't beleive that! Talk to Mr Injector. Unless they have failed electrically I've never seen one that could not be serviced. Well this is for GM TBI injectors... he won't charge if they can't be serviced.

You still need to figure out if that ECM can be used to fire them that way. I don't believe it will, but do not know for sure?

 

Apparently there is enough corrosion inside them that they don't even budge. I tried activating them manually before cleaning and I only heard one of them clicking and just barely audible at that. He only charged me to clean and test one of them and returned the rest. Only one way I'm going to find out if that ECM will fire them and that is to put in good injectors and try to start it again.

 

vinegar or muriatic acid ? ,Maybe get a intake and fuel rails and use your tb just take off the injector pod.

http://www.ebay.com/itm/BBC-CHEVY-Al...08e95d&vxp=mtr

 

Looks like sooner or later you will be calculating injector sizes and fuel-pump capacity. When in need take a look at http://www.hotrodderapps.com

Happy new year!!

 

Happy new year! Those look like some good apps, which ones have you used?

I've got my fuel pump and injector sizes already. walbro 255lph @ 21psi has flow for over 500HP, (4) 72 pph PnH TBI injectors also are good for just over 500HP for my 8.2L BBC...my 5.7L SBC in the Camaro incidentally ALSO uses the same pump, injectors and 900CFM TBI, the only difference is the car has a holley ECM and a 5 pin bosch WBO2.

STILL waiting on my replacement injectors!

 

No, the only time you'll see zero volts on either of the injector terminals is when the ECM drives the 12v to ground (too fast for you to see it.)
If you probe the injector while cranking the volt meter reading should fluctuate, but a injector Noid light is what should be used to see the pulses.

 

Injectors for the truck are taking too long so I thought I'd try using the Camaro's injectors.

This 730 ECM must have been modified quite a bit because it fires both banks of injectors (each bank connected to two low impedance, 4/1 PnH wired in series) just fine.

It took a bit of initial timing adjustment and opening of the idle setscrew to get it to start AND I still have to touch the throttle a bit to get it to run. If I just turn the key, it fires but its like its not getting enough fuel. The engine stays steady at 2500 RPM and closing the idle setscrew doesn't change its speed, even after a full warm up.

--Does anyone think this could be an IAC issue or do you think the ECM chip has been set to idle at 2500 RPM? It doesn't throw any codes at me, if it was an IAC issue, would it?

It handles zero to full throttle revving in neutral without a hitch, doesn't bog at all right to 6500 RPM. I took the truck around the block a few times, its icy as hell out, the truck has all seasons, 2WD, open diff so I was going sideways a LOT. Couldn't find much traction anywhere but in 4th gear with the engine down at 1300 RPM and part or full throttle input it wasn't bogging but inevitably lost traction on a wheel more times than not.