I have a head scratcher here. Ingersoll air compressor with Ingersoll Rand brand diesel engine (made by Isuzu not Yanmar). It will start and run as long as you hold the key on start. I tried a new key, relay, and then started checking every wire. Turns out I do not get 14.7 volts from the alternator...it does not output anything just shows battery voltage. So I decided to put a jump wire on relay pin that is fed by the alternator (hoping that would fool the relay into keeping the fuel shut off solenoid on when I let go of the key and let it go from start to run) but the fuel shut off solenoid closes right back up the second you let off the key from start to run. If I bypass the fuel shutoff solenoid the machine works beautiful EXCEPT of course the alternator is not charging. So I have a replacement alternator coming - however I am unsure if that will help me figure out when the fuel shutoff solenoid won't stay on once it starts. Its the only thing I can tell would get power to the relay after the key is switched to run. Any ideas?
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Ingersoll Rand/Isuzu Diesel on Runs with Key ON
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heymccall
Senior Member
Is there 12v on the red wire (in run) at the stop solenoid?
Yes but only if you hold the key on start which is bringing juice in from the key. On run there is no 12V at that same relay from the key and I BELIVE but I am not sure that the 12V is to then come from the alternator? I need to reread that electrical diagram and maybe a little closer. Would a picture of the diagram help you determine where the juice is to come in after start voltage is removed from the relay (this same relay is where the fuel shutoff solenoid is wired in)?
heymccall
Senior Member
I'm used to 3 wire stop solenoids.
Black...ground
White...pull in
Red...maintain
On or two aftermarket ones for my Yanmars had to be repinned as the white was the maintain.
How many wires on yours?
And, yes, a schematic would help immensely.
Black...ground
White...pull in
Red...maintain
On or two aftermarket ones for my Yanmars had to be repinned as the white was the maintain.
How many wires on yours?
And, yes, a schematic would help immensely.
I am used to the 3 wire myself. This is factory 2 wire per the diagram and that is what it has. Solenoid works fine but I am not getting juice to it once I let go of the key. I am wondering if from the diagram you can tell which of the other power sources could be neglecting to send power. There are 3 gray and gray striped wires that all come to the solenoid and then the 1 solenoid positive wire connects to 3 gray wires. I have a new alternator coming but I don't know if that would change anything here (there is that VIO/YEL wire that goes from relay to alternator and that relay also sends power to the fuel solenoid from Gray/Black). Gray/blue is sending power TO the hour meter right? Gray solid connects to oil pressure switch but if I touch those wires together it still doesn't change a thing and the fuel solenoid switches off the second I turn from start to run.
398370
Well-Known Member
Grab a test light check power at engine temp sensor and oil pressure sensor could have bad sensor
heymccall
Senior Member
Turn the key to run.
Is there 12v at (1)? Testing at (1) eliminates 2 switches (3 if it has the low fuel shutdown).
Is there 12v at (2) (pk w/bu)? No sense in testing the other side (lt bu/rd).
Your answers will tell us where to bypass. Reading the schematic, there are no relays involved in staying running, nor is the alternator involved.
Is there 12v at (1)? Testing at (1) eliminates 2 switches (3 if it has the low fuel shutdown).
Is there 12v at (2) (pk w/bu)? No sense in testing the other side (lt bu/rd).
Your answers will tell us where to bypass. Reading the schematic, there are no relays involved in staying running, nor is the alternator involved.
Last edited:
MarshallPowerGen
Senior Member
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Have you checked oil pressure, engine temp and compressor temp switches (or the wiring to them)?
Thanks folks! I have power at 1. I do not have power at 2 (either of the oil pressure wires). Now this is with the key ON and engine not running. Is RED/BLK ultimately the power source to the oil switch? I do not see a low fuel shutdown as it doesn't even have a fuel gauge.
mg2361
Senior Member
With key on there is supposed to be 1 hot at the temp switch right? And if not I go back to the compressor temp switch and again with key on there should be 12V right?
mg2361
Senior Member
If you have voltage to #1 (Bypass Relay) pin 30, then you only need to go back as far as the engine temperature switch. If it starts and runs while holding the ignition in start then there should be voltage to pin 30 of that relay.
Sorry now I am messing up the process - I checked just now with the key on (not start) and there is NO voltage at 30 on bypass relay. So we are not getting juice on RUN position to 30 on bypass relay.
EDIT: should I be chasing back YEL/BLU wire that goes to bypass relay?
EDIT: should I be chasing back YEL/BLU wire that goes to bypass relay?
mg2361
Senior Member
No. Yellow/Blue (Pin 85) should only have voltage when cranking. Pin 30 should have voltage any time the ignition is on.
Thanks. I will pull the wire that goes to 30 out of the loom and chase back to the key but it might make sense to run a new wire from run to pin 30 on relay.
mg2361
Senior Member
You need to find out why pin 30 has no voltage. So you have to back track on the schematic from there. Jumping voltage to pin 30 will not keep the unit running when you stop holding it in the crank position. That relay is only for bypassing the shut down system until you achieve engine oil pressure.
mg2361
Senior Member
With key on I have voltage at one side of both the thermal sensor (TS1) and compressor temp switch. The wire that is bringing juice into each of these sensors and have voltage is PNK/VIO. Are either of those sensors supposed to always provide 12V unless there is an overheat situation?