Noobie here needs Fuel pump help!

[JRSGTS]

Wasn't too hard a guess because the original spade conn. was still in tact and I read ..Somewhere That there should be one in that line.....AND still never clued in to it going to the wrong Batt. post!! UGH...

Moving on.. I heard it run!! As predicted Sarah, It runs like crap... I changed out all the old fuel.(Full tank!) Blew out the lines and filter.( now new). Installed NGK'S Barely firing. My "fix" for the coolant "switch" didn't work. The wires broke off too short. Auto parts can't find me one. I really don't want to wait a week for another. What does this thing do? The FI bible doesn't talk about it. I do have a new coolant "Sensor" coming in the AM. The other similar looking sensor the thermotime switch correct? The only way I could make it run was to advance the hell out of my timing, I know I'm rich as rich gets. Can this ALL be the coolant sensor?

Really cool stuff you're doing len with the ECU build. Been following it..Not understanding a lot, but I get the idea. Love that cam, crank sensor, with COP idea!

Any help on the sensor stuff would as always be appreciated!! JR.

[JRSGTS]

Another quick question? Does this system have any kind of diagnostic link? Is there any way to read data?

And I mean like Data I can read like basic sensor's and such... JR.

[Zed Head]

Realized that I was looking at the wrong wire in the 76 diagram. There are three connected to negative, the big cable to the starter lug, a wire to ground, and another (the one we're talking about) which connects to 5, 16, 17 and 35 and the coolant temperature sensor. A dedicated isolated ground for the EFI system, apparently. 5 is also connected to 72 of the EFI relay. In short, the star ground shown in the Engine Fuel chapter, with 5, 16, 17, 35, 49 and 72 is actually the dedicated wire to the negative post. If that wire is disconnected, parts or maybe all of the EFI system is not grounded. New learning for me.

superlen must know this but I was never sure of what that wire was connected to. I sure didn't know that it was the ground for the coolant temperature sensor. It should be a focal point for anyone seeing high resistance on the coolant temp. circuit.

I went out and measured resistance from that small gauge ground wire back to the battery negative post and got 63 ohms. Resistance from the negative post to the valve cover was 0.7 ohms (control measurement). I assume that I was measuring resistance back through some resistors or transistors to ground. So, connecting those wires backward at the battery may or may not be guaranteed to cause damage. It's not a direct short but it's not open either.

Had to write all that down just to burn it in to my brain.

[Zed Head]

Can this ALL be the coolant sensor?

The coolant sensor is one of the major control components in the EFI system. If it's not connected the ECU "assumes" that the engine is stone cold and that it's in Antarctica. It has to be connected and working correctly to even have a shot at the engine running right.

[superlen]

+1 again on what Zed said about coolant sensor. The cold start valve could also be a contributing factor, but I think you're on the right track with the coolant sensor wiring. You can take the cold start valve out of the equation by pinching off the fuel line going to it with a pair of small vice grips. Then if you are still running way rich you will know its just the ecu.

Oh, and there is ZERO diagnostic feedback from the ECU. It's only function is reading inputs & firing injectors. There is no way to read sensors & not even an idiot light to look at. That's another reason I wanted to do the HellFire project.

Len

[FastWoman]

+2. Yeah, the coolant temp sensor is THAT important. With an open circuit, the engine will be blowing thick, black smoke out the tailpipe. The reason the "noid" bulbs flash very brightly is that the injector pulse is very long. This usually indicates a CTS open circuit.

I would suggest you measure the CTS resistance from the ECU connector, as that will confirm that all your connections are also good. As Lenny points out, there are no diagnostic capabilities. The ECU actually has analog circuitry, not digital! So the way you get data from this EFI system is with a multimeter and/or oscilloscope.

[JRSGTS]

Cool, Cool so I'm on the right track. I am still unclear on what the temperature "Switch" does. It appears to be wired to one of the relays on the pass. side inner fender. According to the color Schematic the bullet connector is red. The lead off the sensor is blue?? There is a red lead coming out of the harness on top of the intake, but it is way too short. I also have one pair of bullet connectors coming out of the harness near the temp. sensors, one white, one black. Any ideas?

I'll let ya know how it runs after I get the sensor in. THANKS!! JR.

[Captain Obvious]

Different years did different things with different versions of a temperature switch. How's that for an all inclusive statement? :laugh:

In 76, the temperature switch controlled spark timing on the non-California dual-pickup distributors (see page EE-26 of the 76 manual) and it also controlled actuation of the EGR system (see page EC-11 of the 76 manual).

Basically, they advance the timing and disable the EGR until the engine warms up to the temp at which the switch opens.

[JRSGTS]

HMMM, well I have a Non California dual pick up dist. Seems I'll need this to work...Guess I have to find one somewhere...Any clue on the wiring. Should it go to the red lead? It (the red lead) traces back to the relay as per the wiring diagram, but doesn't reach. Maybe there was another lead that is missing? I can make one NP, just trying to make sure....

[JRSGTS]

Could be why I had to RETARD my timing so much...I know I said that wrong in my earlier post, I always phrase it backwards.. If I don't have an EGR valve, it must control spark adv. in my application correct? So there is probably no living without it.

[JRSGTS]

OK, Coolant sensor made a LITTLE difference. I can make it run. Starts barely. Sounding like it's running on 3 cyl. gently rev it and the others come alive...Still eye tearingly rich with black plugs. If I jumper the red lead to the temp control relay it runs better. I must need that sensor pretty bad. Doesn't seem like all of it though. Looking back, my AFM resistance checks were a bit high. Could that be bad? I know there is an air temp sensor in there too. Trouble codes and data would come in real handy right now! I did actually move it under it's own power! Progress I guess.

Need a "Hell fire" test mule Lenny!?

[FastWoman]

It's quite possible your cold start valve is stuck open, either because it's jammed up or because the thermotime switch isn't working properly. That could be the source of your eye-stingingly rich mixture. (Pinch off the hose to see if the engine runs better.)

Also check the throttle position switch for proper operation and adjustment. You might be getting WOT enrichment, which still wouldn't account for eye-stinging richness, though.

Finally, you might run some Chemtool B12 through the system to clean up all the injectors. Maybe they're sluggish?

Edited December 3, 2013 by FastWoman