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Let me see if I understand how this system works. I think key to understanding this is to realize the run switch in the air flow meter opens when the engine is running (kind of bass ackwards). Also the wires going to the alternator just provide an engine ground.
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Everything looks right except for..........
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Rick, This is an excellent write except for the flow switch operation. When the engine stalls, the AFS plate drops down and closes the switch, Not open as you have stated. Maybe a typo? Tony |
I think I'm honing in on the issue. I've ran all the tests again and everything checks out.
While running a test on pin 30 of the relay socket with a test lamp and lifting the AFM plate, I noticed that just as I start turning the key (the moment the gauge lights come on), the fuel pump does run. But, it shuts off as I turn the key farther.... The ignition switch!!! I made a video. At 4 seconds and 11 seconds in, just as I turn the key the fuel pump runs for a brief moment. https://www.youtube.com/watch?v=0EnVJgug074 This is repeatable. And I know: FP is good FP relay is good wiring to the FP is good FP relay socket tests good ground and wiring to AFM is good AFM switch is good everything I've tested checks out |
Have you thought about hooking the test light up to relay pin 30 to monitor what goes on during a start cycle? You could also monitor it at the warm up regulator.
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I realize now that the video doesn't show a lot unless you were there. I had the test lamp hooked up the pin 30 and it did confirm that the fuel pump was getting energized for 1/2 a second just as I turned the key. (I should have included the test lamp in the video.)
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This was performed as instructed.......
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A test light was connected to terminal #30 with the FP relay installed. This was part of a series of tests conducted to determine the intermittent failure of the FP to run. Anthony noticed that by wiggling the ignition switch key between OFF and ON positions he could momentarily make the test light and FP to come on. And he had replicated this several times. Tony |
Is that normal for a CIS car? That seems like an awful long time for the relay contact to transfer. Long enough to overcome the inductance in the fuel pump motor and get it to spin (to make a noise).
What happens (light indication) when you turn it to start, start the car and release the key? |
I am of the understanding that this is normal.
It's my understanding that when you turn the key to the start position that the fuel pump will be energized for 1 or 2 seconds then be de-energized when the relay switches over to the starter relay circuit. This was done to prime the system just before start up. I think that if Rick's point #3 is correct that it confirms this. Also I recall that Tbitz had to modify the megasquirt program to do this same operation when doing the EFI conversion. I may be totally out to lunch but I thought that Porsche implemented this in their circuit and therefore the one of the reasons for the red relay to allow for this delay in switching. As I said I may be totally out to lunch on this. If so disregard. |
Yes, did that when I replaced the alternator. The car even ran perfectly with no alternator installed. I probably started it 20 times to move it around. After the new alternator was installed the car ran great briefly. Voltage at the battery was good, thus the new alternator was working properly. And then it stopped running again!!! I thought it was related to the alternator so I was led down the wrong path initially.
Tony really helped me step back and test each component step by step. I really appreciate Tony's aid in helping me set up proper tests to check the FP, relay, socket, AFM switch, etc. And now I have this great understanding of the FP, relay and starting circuit. The car is still not fixed but a new ignition switch has been ordered from Pelican. I heard it's a pain of a job but will be nothing compared to the days and days I've been banging my head against this problem. Hopefully, we'll be up and running next week. Quote:
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and run normally. This will bypass the #15 power provided by the ignition switch if it's really bad and power the FP relay pins. Since there's just one #15 contact on the ignition switch, no #15 power will be provided to any other electrical requirement, e.g. the light/radio, if the switch is bad. So before actually replacing the ignition switch, you need to use your test-light to check the various powers at the ignition switch, i.e. X (if it has one), #15 (run), #30 (constant power), #50 (start). |
With the test light on the circuit that connects to the fuel pump, pin 30 of the relay or the warm up regulator, what does the light show when you start the car and it stalls?
Does it flash when you turn the key on, come on with the starter and then stay on or go out when you release the key? It sounds like everything works except power to the fuel pump with the flow switch on (open). Quote:
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What happens when you turn the key to start and the engine fires and you release the key? |
OT: if you see a post from someone with an almost meaningless name and posts fewer than 10, ignore and do not quote. Those posts have a hidden image linked to some site, most likely to increase their search rank. (More links increase rank.)
BTTT, I see you are in the Bay Area. I am in San Jose. PM me if you need just an extra set of hands, literally. No tech knowledge whatsoever (unless you count computers). |
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I deleted my last responding to that guy. I did notice that image link in the quote. Now the guy is just repeating what I wrote. Hard to believe that this helps someone's business. |
This problem, like many, has become overly complex. It should have taken 5 minutes at
most to solve and not over 75 posts and more than a week of troubleshooting. |
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points and properly tested the ignition switch, but you've ordered a new ignition switch. Hopefully this will not be a waste of time and money. The "shotgun" approach to parts replacement does work on occasion, but not always. |
I agree and I realize I'm taking a $100 chance on an ignition switch. And, if that isn't the case I've gotten a lot better with the test lamp and multimeter. :-)
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