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Discussion Starter · #1 ·
I’ve had this Hyundai Santa Fe for a few years now and it’s been a great car, up until the last couple months. This started with a hot issue, where the car would start to kick and buck under load at operating temp. After letting the car cool down for a couple hours, it would restart and run normal until back at operating temp.
That issue got progressively worse, rapidly. And it wouldn’t start anymore. Starting with fuel I checked fuel pressure, and had 38 psi at the pump, went ahead and replaced the in tank fuel filter. This got me to where it would run and die after 3-4 seconds. This continued for a couple weeks until it wouldn’t start anymore again. Checked for spark and had none. After some reading on here determined it was a cps/cks issue. Borrowed a buddies code reader, and had a stored and pending code both for ckp. Replaced both cam and crank sensors. Still no spark, checked for voltage at the coil and found none, so for diag purposes, wired a ign on hot wire to the power feed on the coils, got spark back but still no fire. Replaced the plugs, and drained the fuel through the return line at the rail and out fresh in. Put my meter on the injector harness plugs, and have battery voltage on both leads, but neither break when cranking. Pulled the rail and injectors to confirm. All 4 injectors dry. So after some more reading, found that if the tps was no good, injectors could die like this, as with the ignition failure circuit. Seeing as I had no voltage at the coil, I went ahead and replaced the ignition failure sensor, and regained spark in the factory form(without a jumper) At this point I still have no injector pulse, but have spark, **** some starting fluid in the tb, and started the car, she fired up, but the tach is dead. Am I missing something obvious? I’ve read that without rpm the injectors won’t fire. Tps voltage measures .33v at closed throttle, and 4.26 at wot.
 

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How are you testing the injector pulse? A meter isn't really the best tool for that job (doesn't update fast enough). Personally, I'd just use a 12V bulb.
Did you try cranking it over when you had the fuel rail/injectors removed from the engine to see if the injectors were spraying fuel?

The RPM signal for the rev counter comes from the ignition failure sensor. It shouldn't have any effect on injector control though. There are a few posts on the forum from folk who have had the rev counter fail but the engine was still running. Since you just replaced the sensor, I'd suggest checking it has a good ground. Connect your voltmeter between the two outside terminals of the sensor's harness connector and make sure you have 12V when the ignition is switched on.

Your TPS output looks OK to me.
 

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Discussion Starter · #3 ·
Was checking with a meter for injector pulse, indeed did remove the injectors and laid the rail where I could see it while cranking, no fuel spraying out. Meter tests on the ign failure were done prior to replacing it and had battery voltage supplying the sensor, when tested on the two outside leads.
 

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Was checking with a meter for injector pulse, indeed did remove the injectors and laid the rail where I could see it while cranking, no fuel spraying out.
You need to determine if that is because there is no injector control or no fuel pressure in the rail. I'd suggest you disconnect one of the injectors and connect a 12V bulb across the harness connector. Keep a close eye on the bulb while someone else cranks the engine and see if the bulb blinks. The bulb wont light very brightly because of the short duration of the injector pulse.
 

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Discussion Starter · #5 ·
I can do that, I can pump fuel out of the rail via return line, and have gone as far as plugging the return line and still no fuel out of the injectors. Will post back with what I find.
 

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It's unusual for the PCM to be controlling the coils but not the injectors. These outputs from the PCM are usually controlled by the same inputs (cam & crank signals).

I think your next step should be to check the continuity of the injector control wiring between the injectors and the PCM. Admittedly, it's a little unlikely all 4 wires would go open circuit at the same time but it seems like the next logical step. I'll attach a wiring diagram if you need it but need to know if your car as an auto or manual gearbox?

Your fuel pump is definitely running DURING CRANK?
 

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Discussion Starter · #8 ·
Pump is running during cranking. It’s an auto, a schematic would help wonders as I haven’t been able to locate one.
 

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On a side note, both injector wires on all 4 measure at battery voltage with the key on.
That's normal. The control side of the circuit is open/off, so both wires will show 12V.
The 12V power supply goes in on one wire, through the solenoid coil inside the injector and out on the other wire.

Diagram below :

 

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Spraying starter fluid fires up engine to run
It becomes a fuel issue.
Just out of curiosity, when you replaced fuel filter, did you check fuel pressure afterward?

As Autospark said, it is unusual to have all four injectors not working
Is it possible that the wiring to and from the ECU is causing the injectors to not fire?
Could the problem be the ECU?
Is it possible to have a shorted sensor (pulling down the 5 volt reference)???
Could a lack of fuel pressure cause the injectors to not fire???
 

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Discussion Starter · #13 ·
On a side note, both injector wires on all 4 measure at battery voltage with the key on.
That's normal. The control side of the circuit is open/off, so both wires will show 12V.
The 12V power supply goes in on one wire, through the solenoid coil inside the injector and out on the other wire.

Diagram below :

I have continuity throughout the harness at the Ecu plug.


Spraying starter fluid fires up engine to run
It becomes a fuel issue.
Just out of curiosity, when you replaced fuel filter, did you check fuel pressure afterward?

As Autospark said, it is unusual to have all four injectors not working
Is it possible that the wiring to and from the ECU is causing the injectors to not fire?
Could the problem be the ECU?
Is it possible to have a shorted sensor (pulling down the 5 volt reference)???
Could a lack of fuel pressure cause the injectors to not fire???
I had the car running after the filter, up to the point of doing the crank and cam sensors.
 

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I had the car running after the filter, up to the point of doing the crank and cam sensors.
Maybe you should go back and double check your sensors in that case. You can feel pretty confident that the crank sensor is working if the fuel pump switches on and off when you try to start the engine, so I'd start by looking at the cam sensor. Check it's 12V power supply and ground by connecting your voltmeter across the outer terminals of the harness connector, then connect the meter between the center terminal and ground to check the signal wire from the PCM which should show 5V with the sensor disconnected. If the voltages are good maybe try refitting the original cam sensor if you still have it since that's only a 5min job.
 

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Discussion Starter · #15 ·
Battery voltage when measured between the two outside pins on the cam sensor, and 5.01v on the middle. No change with the old cam sensor.

In regards to my having the car running after the filter, and before the sensors. I was messing with it one day and noticed no voltage on the coils, bypassed the ignition failure sensor, and fed a Key on 12v lead to the coils, and it ran great for 30 mins. Turned the car off, went and did something for about an hour, came back and it started rough, and would break up when revved. Put the code reader on it and it had a code for a crank sensor. Cleared the code, tried to start, and an immediate code again for crank sensor. So I put a crank sensor in, already had a cam sensor, so popped it in too. No start. Ether, and it would start. Thought bad fuel after sitting for months, and drained it and put fresh in, no start. Plugs were fouled, out a set in, no start. Checked voltage at the injectors, and had no change with the fluke meter on. Pulled the rail, no fuel spraying. This is where I am. No injector pulse. Is the Ecu the primary control of injector pulse? If so what tells the Ecu when to fire the injectors? Crank, cam, both? Totally lost at this point, unless I do indeed have a bad Ecu.
 

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what tells the Ecu when to fire the injectors? Crank, cam, both?
Crank sensor. But it's the crank sensor that controls the fuel pump relay too and that is working properly.

Maybe take a look at the engine RPM on the scan tool data list and make sure it's displaying engine speed during crank just to be sure.
 

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Discussion Starter · #17 ·
I know there’s no rpm on the dash when she fires on the ether. Will check cranking rpm tomorrow and post back. Thanks.
 

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Discussion Starter · #18 ·
Still no luck on getting a scanner to read data. Once I get one, if I don’t see cranking rpm, what would my course of action be? If I do see cranking rpm?
 
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