OK ,
Ya’all i’ve run thru
most everything i can , ans have eliminated a lot of possibilities . here is what i have and what i know…….

1975 with newly installed rebuilt long block 2056. motor has been back in for 2 weeks, i’ve been through the break in and runs awesome .
i have d-jet, OEM original ECU, 123ignition distributor MPS built by Jeff Bowlsby, harness for FI and alternator were new from him just a few years ago, all clean and were on the car before i pulled the motor for dropped valve seat.

fuel pump confirmed good and puts out pressure when it gets signal..
so what it’s not- not a bad pump.
fuel pump does not prime when key is turned to on position- BUT with the cover to the FI pump relay in back removed and opened if i press the top of it as suggested as a test by George in his Tech Tips book, chapter 9 #560, the pump then primes. so #30 pin at relay has power, but the ignition is not triggering the pump to prime or run … George says this test rules out the board and pump-
#2 ignition switch- i had a spare so i pulled it, and replaced it- same issue no fix. So it’s not the switch but could it still be the board? or ECU?
even thought the pump primed the injectors are not pulsing.
Coil is new, it has #12v at it with key on, so power is going to the dash, to the starter because it cranks, and to the coil.
all other things work- dash lights, etc etc. tried swapping relays this does not help. i have tried different cht ans mps but i didn’t expect that to work, no change.
with key on, shouldn’t one of the 4 blade connectors for the FI harness on the board have 12v? none do. would this be switched power? or would i have to be cranking to make the ecu send a signal to the board to fire the injectors?
So either way when the key is turned the pump should prime and the injectors should pulse, they don’t.


first time it happened i though i just didn’t have timing set , but i got in and turned the key - bam , fired right up, ran took test drive , etc. was not until a week later that it happened again.
- power is getting to the board but not to the pump, we’ll it is if i press on the open relay so thst circuit is complete- it does not get triggered by the ignition switch to prime, so the short is somewhere between the ignition switch back to the relay is my guess -
thst means it’s possible the ecu is not completing the circuit. or ignition switch…

ok that’s the story
Help.

i wont get time to work on this until tonight, but thru google search i found a couple helpful world and pelican threads including the PBAnders flow chart for testing the board.
I will go thru this tonight and i hope i can report back results. based on my sx and what others have seen its most likely a short in the board that is not allowing power to go from the power relay to the FI relay to power the pump and the injectors.


http://914world.com/bbs2/index.php?showtopic=210991

If i had known how to properly test this and jumper to fire the FI and pump on thursday i could have been back on the road in a matter of less than an hour.

I am getting anew board but i still want to go thru this one to see where the fault is exactly .

Anyone else deal with this i would be interested to hear how you figured it out and what the solution was.

Phil

The 2 second priming comes from the ECU. So the signal from the ECU is not getting to pin III of the ECU power connector on the relay board.



This test only verifies that the power to the FP can get there if the relay closes. It would be better to pull the ECU power connector and ground pin III of the ECU connector on the relay board to see if the FP runs. This would test everything from the connector to the FP.

Do you have power to the ECU on pin I?

Years ago a buddy of mine had a no start issue like this. He kept throwing parts at it in hopes that one would fix it. I was helping him out one day and I ended up moving the CHT sensor wire and it fired up. Now that was an accident but we found the wire to be bad. Replaced the sensor and it ran just fine. Not saying it's your problem but hey give it a look.

I had a no-start recently due to a bad fuse on the relay board that looked fine. (I notice you're running a blue 25 amp fuse, shouldn't that be a red 16 amp?) Followed the next day by a no-start due to broken CHT lead. This was a short while after re-installing the engine so there had been a lot of fiddling with engine harness when replacing intake runner seals, etc. In both cases it was the most common problem.

When I had a no start issue with the fuel pump not running and the injectors not pulsing it ended up being a failed ECU. Maybe try swapping with another one even if it's the wrong year to see if the pump runs.

http://www.914world.com/bbs2/index.php?sho...=332008&hl=

No, i dont think so, so that may be were the break is, when the key is on i should have pwer at the #1 spade of the 4 prong. that was one of the first things i checked. so if thats the case then the signal is not getting from the board to the ecu on that circuit correct? i am going to try and jumper that from the #87 at the power supply relay to the #1 and see if that works?

Phil

yea, i just installed my motor too, and like you tuning and a lot of fiddling. thing is it was intemittent too, where it had started and then stalled and no fuel pump signal, so intermitent short or contact.

My fuse is working, the power does get from the fuse to the relay both the #30 pins have power. My CHT is new did a double check on that too but i will recheck this CHT again to make sure,so thanks for the suggestion.

I think Mark is on the right track with the #1 spade not having power at it. and it will be as simple as checking continuity between the #1 spade and the 87 of PS relay and the 85 socket of the FP relay that both are on that tracer.

I have both a new board on the way to test and Richard(Gatornapper) is sending my his 75 ECU that we know is good, to test if the board ends up not being my issue.

@MDTerp
@TX914
@Spoke
@Luke _M

did you check the goodness of the ground connections from the control unit wiring harness at the back of the engine block

@dr914 @autoatlanta.com
George, yes. Funny thing on that, as i reinstalled the motor and harness right before this last week, i went down my cneck list of grounds and contacts etc to verify, and i had put the ground connector on and apparently only finger tightned that bolt. so as i was driving out of town i started getting a sputtering , so i pulled over, went back and checked all the contacts and came to that one and sure enough it had vibrated loose and was almost off!!, once tightened down i was good for the next 250 miles until we stopped in Spartenburg SC and my new issue came up. Its in there tight for sure, but i appreciate the suggestion . In that situation the pump will prime you will have pressure but not firing of the injectors. right now i dont get either.

Also want to give a huge shout out to AA and you and Andrew . 2 weeks ago i had made an order that i really needed or i would not get on the road last week, and it didint get out due to one of the parts in the order not being in stock, i called to get the other parts out anyway and you guys had it out that day and i had it on saturday just 2 days later!! i just wanted to say THANKS!. No one else was willing to get those parts out to get them in time!!

Phil

I have a section on my web page for testing this system, but the flow chart tool I used is no longer supported. So, we're back to using the schematics to test the system.

When everything is working correctly, the fuel pump runs for 1.5 sec after the key is turned to "on", to pressurize the fuel rail, and shut off to prevent pumping fuel everywhere in the case of a leak. So, the basic test for operation is to sit in a quiet garage, turn the key to "on" and listen for the 1.5 sec of the fuel pump running. This verifies that you're getting power to both the ECU and the fuel pump. No sound? Start looking.

First place to look is the last link in the chain, the fuel pump. Hook up your DVM and turn the key. If you have voltage and the pump doesn't run, it's bad or possibly has a faulty ground. No voltage? Check the power supply pins to the ECU, and verify the ECU ground connection is good. If you have voltage there where you turn the key to "on", check pin 19 on the ECU connector, and see if you get voltage for 1.5 sec after the key is turned. No voltage? Your ECU is bad (very unlikely, but possible). You see 1.5 sec of voltage? Go to the next step.

If there's no voltage at the ECU, or if you see 1.5 sec of voltage at pin 19, but the there's no voltage at the pump, then it's back to the wiring harness and the relay board. Pull the schematic for your car and trace the voltage path. Somewhere, you have a fault. It just takes time and patience, check the harness connection from the ECU and fuel pump back to the relay board connector. From there, check the relay board traces, then the relays, then the power supply connector to the relay board. Then check the wiring harness to the ignition switch, the the ignition switch, then the wiring harness connection to the battery.

BTW, if the fuel pump runs for 1.5 sec, remember that if the trigger contact points connector isn't plugged in, the pump won't run when starting because the ECU has to sense that the engine is turning over more than 100 rpm for the fuel pump to operate. Just something else to check.

BTW, I'm sorry for the generally poor functionality of my website, but I have no access to it to fix it. I've tried contacting rennlist repeatedly to gain access to the editor, but I get no response. Eventually, I'll host it somewhere else, but I would like to have access at least to provide a redirect.

I'm having a hard time keeping track of where we are, so let me try to recap:

1. Car was running fine, made it part way to Okteenerfest, stopped for a rest and it would not start after that.

2. Fuel pump did not run for it's 1.2 sec initialization when ignition was turned on.

3. Fuel pump was jumpered to run continuously, but still would not start.

4. Manually activating fuel pump relay causes pump to run.

5. 12V present at coil which should verify that ignition switch is ok.

6. 12V to coil is same circuit that activates the ECU relay, so that should be activating. (not sure that this has been verified)

7. Although CHT has been checked, it would not cause these symptoms. It has no influence on the activation of the fuel pump.

@DRPHIL - did I get this correct? If so, my next steps would be:

Click to view attachment

@pbanders
@Spoke
@JeffBowlsby

i just went to Jeff Bowlsby's web site - https://bowlsby.net/914/Classic/TechNotebook.htm

He has your flow chart etc in a PDF that is readable and can be copied or printed out.

I think the corrections in that @Spoke mentions in the 2016 thread with you were made but i will look to make sure. Good to know its still out there in a form that can be viewed.

Phil

@adolimpio
2. it does not or didnt BUT, there was a moment for no reason it suddenly did and car
did run for about 30 seconds, then just stopped, so again check and no pump prime sound or injections - and that was it, - got it home went out the next day, just for fun tried to crank it turned key, nothing, then again and - same thing, started briefly, pump and injectors were going then stopped getting signal again.

Yes, in a nutshell except 6. i will check this to make sure - --

Phil

@DRPHIL914

Phil,

Please confirm these 2 tests:

Remove the ECU 4-pin connector from the relay board.
Remove the +12V wire from the coil to protect any components which might be affected by leaving the ignition ON with the engine not running.
Turn ignition to ON

1) Measure voltage at ECU 4-pin connector terminal #1. What voltage to you have?

2) Ground ECU 4-pin connector terminal #3. Does the FP run continuously?

Wow....look at that diagram. Nice. Do what Spoke says Phil. I had this problem long ago IIRC. Turned out to be a intermitent cut out and a sliced or cut in the wire out of that harness. Left me stranded at the Santa Monica Pier a while back.......probably 15 years ago now!

@DRPHIL914

BTW, be very careful when measuring terminal 1. The power to terminal 1 comes through the power supply relay then straight to the battery WITHOUT a fuse.

Likewise when grounding terminal 3 use a wire with a spade connector and not a bare wire to touch terminal 3. The ignition switch should be OFF when you attach the wire. Attach the wire then turn the ignition switch ON. Terminal 1 is not fused and catastrophic damage may occur if your ground wire on terminal 3 accidentally touches Terminal 1.

I may have missed it but have you verified spark? If so have you pulled an injector and tried turning it over to see if you are getting fuel at the injector?

good to know, will be very careful on this not to cause a short between the #3 ground and the #1 there when testing. I will get into this tonight and report back.
- agreed, nice diagram, it makes it a bit easier to see the flow and understand.

We tried to call you from Okteenerfest, but didn't get through.

This may help...



On the ecu power supply relay, make sure pin 30 has constant power. (Red trace in diagram)

With the key on, make sure there is power to pin 1 on the 4 pin connector for the injection harness.

It could simply be the ecu power supply relay went bad.

Clay

I chatted with Phil this morning.

He has 12V at the coil which tells us that there is voltage on the circuit which supplies the ECU relay. That circuit comes into the relay board on pin 8 of the 14 pin connector, connects to pin 85 of the ECU and Heater fan relay and goes out on pin 7 of the 12 pin connector and on to the coil.

He also said that he cannot hear or feel the relay click when plugging and unplugging it, and he said that it is an old conventional relay, not solid state.

Given this, when he is off work later today, I asked him to:

Check for 12V on pin 85 of ECU relay.
If 12V is present on pin 85 then check for 12V between pins 85 and 86.
If 12V is present between 85 & 86 then the relay should be replaced.
If there is no voltage between 85 & 86, then it is a ground issue.
If there is no 12V on pin 85, then a trace on the relay board must be defective and the relay board should be replaced.

My money is on a ground issue!

@spoke There is an error on your schematic. Pins 85 & 86 are swapped on the relays.

Clay, we were in a bad spot snd cell coverage was iffy zap i missed the call while we were trouble shooting, but on the spot thet day and again at home , also rechecked last night i had no power at the #1 spade, and i do have 12v at the board fuse and at the FP relay #30 but not at the power relay #30. i pulled th board last night ans cleaned the contact pins and also slid a razor into each pin to slightly push apart the pins to tighten up the contacts , rechecked all the body grounds ans the FI motor ground connection. tonight as Artmsaid i will go back and check the power relay #30, also the 85 ans 86 again. the relays were swapped and checked and i also have some new ones but anyway too good relays from the headlights and swapped snd it didn’t help. no change . either it’s a board short or grounding issue, hoping for the test tonight to help clarify it. Coil gets 12v and so does the starter. pretty sure it’s not the ignition because power is coming back from front to back thru the switch but ECU is not getting power or maybe not grounding .

@adolimpio

Thanks for pointing that out.

My Carbooks 914 1970-72 shop manual and Haynes 914 Owners Workshop Manual has 85 and 86 swapped. For Haynes, only the "up to 1971" picture is like my original. The 1972 and 1973 relay board pictures are correct.

Here's my schematic corrected.

Click to view attachment

@DRPHIL914
@adolimpio

FP relay pin 30 comes through the 25A fuse from 14 pin connector pin 14 directly from the battery.

Power Supply relay pin 30 power comes from 14 pin connector pin 12 directly from the battery.

Pins 12 and 14 have separate wires directly to the battery.

If the PS pin 30 has no power then either:

1) The socket and/or connection to the relay board for the Power Supply relay is suspect
2) The relay board traces to pin 12 is suspect
3) The pin 12 connector/pin is suspect
4) The wire from pin 12 to the battery is suspect

Nice, it's a nice piece of work. Thanks for fixing.

UDATE:
after taking the board out last night , i cleaned up all the contacts, and tested all the circuit, i didn’t find one bad one, all had continuity, so figured then we were probably getting a bad connection to one of the pins, looking at the circuits that were not seeking to work, the FI, either was supply or ground, i stretched open the pins a bit by sliding a razor blade into them so that they would be tighter into the socket of the 14 pin harness plug. so tight i reinstalled it, then one by one slid the relays into place, after having put the harnesses on the board, and felt the click of the relay, and the pump primed! OK we had contact and power. car started on first try, so set off doing the timing, it suddenly stalled, so i checked the key, off and back on no pump prime- moved the 14 pin plug slightly ans it primed, and started. so i have a pin/socket connection that’s not making a perfect connection. after pushing it down tight ans making sure it was full seated , i took it for a drive around neighborhood and no issue.
So looks like it’s #1 on @Spoke s list . i may disconnect the battery and take the box over off the plug ans check the wire and pin solder connections.
I will keep the other board i just got in the car ans close by. For now i will stay close to home, but at least we have a good idea of the approximate location of the issue.

Keep troubleshooting it.

But if it strands you away from home again, just jumper pin 30 to pin 87 on the ecu power relay. That will turn on the ecu and you will be able to drive home.

Clay

I just had a similar failure that briefly stranded me along the freeway. This was actually the forth time it had caused the car to die but it restarted the first three times.

Mine turned out to be loose connections at the fuel pump relay.
It was a new relay and the pins did not fit tight in the relay socket on the panel.
The relay could wiggle and connect or disconnect, like when I went over bumps.

I got it tight enough to get home and the use the razor blade trick to spread the pins of the relay so it fit tight into the socket.


Good luck
Jim

@ClayPerrine - thanks for the tip, will keept that at the top of the list of "need to know" items for this

@jcd914 - yea thats where i started and then went to the harness pins, but not sure i have completely solved this for sure. I am going to take a look inside the cover at the solder connections in the plug. I used the razor on the pins on the board but what about the female socket end inside the plug? seems that might be the issue.

I may also try the new board, if it happens again i know its in the plug .

at least i know its not somewhere else in the harness or the ECU.

I am hoping to get some time this week driving it around town and maybe to work a few days, i need some more break in miles