77 280 cold start vs main injectors

[Zed Head]

Pins 16 and 35 are ground circuits.  That "point" is the one that you said was missing earlier, from siteunseen's picture, in Post #19.  If you measure low resistance to the body or the battery negative cable, you're probably fine there.

 

Funny, but there is so much information out there and so many different ways to do things that new things keep popping up.  New to me anyway.  You've been focused on the flashing light method, but your first picture above shows the sound method.  I was aware of it but hadn't thought to mention it.  Some of use use a jumper to coil negative to do the same test.  Didn't know the Guide had a variant.  Do you get any clicks if you try that method?  I posted a copy of your copy.

 

 

Also, are those your notes written by each test procedure?

 

Looks like the harness has already been repaired, what would you do differently?

 

Sorry to keep jumping on your posts.  If someone else wants a piece of the action, please enter the fray.

Edited December 16, 2015 by Zed Head

[rosaluma]

Thanks for the input, please any and all suggestions are helpful.  I agree that the repair that the previous owner made looks good enough to me.  With regards to the notes, they are mine, and are the readings you were requesting, earlier.  I did listen to the injectors, and heard a rythmic clicking.  The only three tests that were funky were pg 50, referring to pin 7 and 8 which go to the AFM, and pins 16 and 35.  That being said, the factory service manual test indicated replacing the control unit, which at this point, is the next step.  I was really hoping it was just a simple ground issue, though.

[Zed Head]

Don't replace the ECU.  If you hear the injectors clicking, then it's performing its main function.  The ECU's typically fail by dumping too much fuel (flooding) or none at all.  But if you're injectors are clicking they are opening and closing like they're supposed to.  Are you sure you're actually hearing the injectors?  You should hear all six click at the same time, each time you break the power circuit.

 

I'm going to hit on the starting fluid anomaly again.  Starting fluid is a very volatile fuel, too volatile to use to drive on, but designed to get an engine spinning so that the normal control system can supply gasoline appropriately.  You're not even getting a "pop" with starting fluid.  You should be able to completely remove the ECU and the AFM and the throttle body and "run" the engine with starting fluid.  The fact that you can't indicates a problem unrelated to the ECU and AFM's functions.  They're not the cause, from what I see.  The ECU and AFM only control gasoline supply, that's it.  With starting fluid, you don't need gasoline, therefore you don't need the AFM and ECU.

 

I repeated myself, to try and get this point through.  You're outside of the ECU/AFM EFI system diagnostics.  You have a basic engine mechanical or ignition problem.  Hard to tell what it is, since you did get cylinder pressure, and you have seen spark.  

 

Here's a simple test to see if your ignition timing is close.  Get the ignition timing mark at about 10 degrees, the rotor inside the distributor cap pointing at the #1 cylinder (the one at the front of the engine), and the cam lobes of that same cylinder pointing up (valves closed).  All you need to do is remove the valve cover.  Much cheaper than a new ECU.

 

Also, I notice that your starting fluid contain "upper cylinder lubricant".  Could be that it's old and the volatiles have been used up and you're just spraying lubricant.  Who knows.  Get a new can of high-power gas engine starting fluid, to be sure.

 

You're testing looks great but there's still a basic problem.  Hate to see people buy expensive parts that they don't need.

[Patcon]

I agree with Zed Head. While most of this 280 EFI is out of my expertise, if it won't run on ether then the issue is not fuel related. Ignition timing, spark or plugs provided compression is good. Is your valve adjustment good?

[rcb280z]

I also think a new can of starter fluid is needed. "If there is spark" that engine should give a sign of life with the starter fluid for sure. Even with a weak spark the starter fluid should make it pop or something at least.

[rosaluma]

I have had pops and flutters, but nothing to sustain it when the key is not in the start position.  Will check cam lobe, etc.  Don't want to replace ECU.

[rosaluma]

   .

Edited December 18, 2015 by rosaluma

[rosaluma]

Cam lobes were positioned to spec. Not knowing better, I adjusted cam so #1 lobe was pointing straight up, which did not help....probably hurt. Now I have to go back to reset.

Edited December 18, 2015 by rosaluma

[Zed Head]

Check this.  With the ignition timing mark on zero, and the straight (driver's) side of the chain tight.

[rosaluma]

Yep, it was in the position located in the before image, before I tweeked.  

 

Now, its off the charts.  Will put back, later tonight.

Edited December 18, 2015 by rosaluma

[rosaluma]

Found the problem, oil pump shaft is 180 degrees off. So, distributor would settle in 180 degrees off. Bad news is I dropped my 19mm socket down the engine cover. I tried magnets coat hangers, etc. I have to take the cover off....good times.

 

Edited December 20, 2015 by rosaluma

[rosaluma]

Runs like a champ, albeit a little slappy.    Will adjust valves, which will hopefully pull up compression, as well.  Thank you Zed, for deterring me from purchasing ECU, saving me $250 +/-, which I will instead put towards wheel spacers.  Any recommendations?  Need about 1.5'-2" in the rear, and about 1"-1.5" on the front.

Edited December 21, 2015 by rosaluma