Hyundai Forums banner

21 - 38 of 38 Posts

·
Registered
Drives : Nissan NV200 Flies : Rans S6ES
Joined
·
14,734 Posts
Testing 86, Red prone to Positive on battery and to 86 shows 0
Red voltmeter probe to B+, and black probe to the relay 86 terminal shows 0V. Sounds good.

kici said:
and then tested to the 4th wire main relay ctrl wire shows 13 V
So with the red voltmeter probe to B+, and black probe to the relay 85 terminal you get 13V.
Meaning the ECU is pulling the relay ctrl terminal to ground. That sounds good too.

Is this the terminal you said had 9~10V in your original test?

kici said:
On the fuel pump (back seat is put up) I tested the black and red to see if anything goes to it when I turn the key - nothing, and i do not hear it.
The fuel pump wont work if the MAIN relay isn't switching on. The MAIN relay supplies power to the F/PUMP relay.
 

·
Registered
Joined
·
10 Posts
Red voltmeter probe to B+, and black probe to the relay 86 terminal shows 0V. Sounds good.


So with the red voltmeter probe to B+, and black probe to the relay 85 terminal you get 13V.
Meaning the ECU is pulling the relay ctrl terminal to ground. That sounds good too.

Is this the terminal you said had 9~10V in your original test?


The fuel pump wont work if the MAIN relay isn't switching on. The MAIN relay supplies power to the F/PUMP relay.
It appears that I must have tested 85 with B+ while the car key was not turned. I just checked without it turned its about 9 something, with it turned I get the 13 V

I'm lost as to what the problem can be,

Another thing I tried was replacing the Main Relay with the Start relay
 

·
Registered
Drives : Nissan NV200 Flies : Rans S6ES
Joined
·
14,734 Posts
I just checked without it turned its about 9 something, with it turned I get the 13 V
From the open circuit voltages (the voltages with the relay removed) it sounds like the PCM has control of the MAIN relay.

Ideally we want to measure voltages with the relay inserted so there is current flow, but it's not easy to probe the relay socket with the relay sitting in it. Ohm's law tells us that the voltage dropped across an unwanted resistance will be proportional to the current flowing through it. With the relay removed there is no current flow which is probably why the voltages look OK.

Try this....remove the relay and switch the ignition on. Now, with the ignition on, insert the relay into it's socket. Do you hear/feel it click as you insert it? Does it buzz/rattle at all?
 

·
Registered
Joined
·
10 Posts
From the open circuit voltages (the voltages with the relay removed) it sounds like the PCM has control of the MAIN relay.

Ideally we want to measure voltages with the relay inserted so there is current flow, but it's not easy to probe the relay socket with the relay sitting in it. Ohm's law tells us that the voltage dropped across an unwanted resistance will be proportional to the current flowing through it. With the relay removed there is no current flow which is probably why the voltages look OK.

Try this....remove the relay and switch the ignition on. Now, with the ignition on, insert the relay into it's socket. Do you hear/feel it click as you insert it? Does it buzz/rattle at all?
No, when I put in the Relay with the ignition on I do not hear anything, no clicks or buzzes, is the relay supposed to make a noise?
 

·
Registered
Drives : Nissan NV200 Flies : Rans S6ES
Joined
·
14,734 Posts
The relay should click when it is switched on by the PCM, and the PCM should switch the MAIN relay on whenever the ignition is switched on. So it should click when you insert it if the ignition is switched on.

OK, what I would do now is take a length thin wire and bare about 10mm of the insulation from one end.
Remove the MAIN relay and insert the bare end of the wire into the 85 terminal of the relay socket, then refit the relay.
Now remove some insulation from the opposite end of the wire and connect your red voltmeter probe to it.
Next, connect your black probe to battery negative and switch the ignition on. What voltage is displayed on the meter?

You should be getting pretty close to 0V since the PCM will be pulling the relay 85 terminal to ground when the ignition is switched on. If your seeing significant voltage on the meter that confirms there is high resistance in the relay control circuit inside the fusebox.

If the test confirms high resistance, disconnect the voltmeter from the wire and touch the bare end to ground (battery negative).
Does the relay click? Do you hear the fuel pump prime? Is there a big flash and lots of smoke....hopefully not :LOL:
 

·
Registered
Joined
·
10 Posts
OK, what I would do now is take a length thin wire and bare about 10mm of the insulation from one end.
Remove the MAIN relay and insert the bare end of the wire into the 85 terminal of the relay socket, then refit the relay.
Now remove some insulation from the opposite end of the wire and connect your red voltmeter probe to it.
Next, connect your black probe to battery negative and switch the ignition on. What voltage is displayed on the meter?
Doing this did not change the Voltage it remained high, so high resistance? :)


If the test confirms high resistance, disconnect the voltmeter from the wire and touch the bare end to ground (battery negative).
Does the relay click? Do you hear the fuel pump prime? Is there a big flash and lots of smoke....hopefully not :LOL:
Alright, so touching the bare wire to ground, did indeed make the Main relay click (it makes it click ea time I get the wire to ground)

The fuel pump however still did not get activated, the reason I know this is because I have the pipes for the fuel pump kit (the 2 hoses) removed from it, I know a bit stupid but I wanted to see gas shoot out to MAKE SURE its working lol.

What's next?
 

·
Registered
Joined
·
10 Posts
Okay this is weird, I tested it in this order:

Turned ignition off, placed wire to ground, turning ignition on (nothing)

Turning key to start, it started shooting out gas...


So thats a victory so far, what is the fix to make this permanent for now? :)
 

·
Registered
Drives : Nissan NV200 Flies : Rans S6ES
Joined
·
14,734 Posts
Turned ignition off, placed wire to ground, turning ignition on (nothing)
The MAIN relay will have switched on with the wire connected to ground. Your basically bypassing the PCM control signal.

kici said:
Turning key to start, it started shooting out gas...
Where was the gas shooting out? Did you have a fuel line disconnected?
The fuel pump is only activated when the engine is turning. That's why the fuel didn't shoot out until you cranked it over.

kici said:
what is the fix to make this permanent for now? :)
Disconnect the end of the wire from ground and splice it onto the black/orange wire at the fusebox connector, as shown in my earlier photo (post #17).
 

·
Registered
Joined
·
10 Posts
Where was the gas shooting out? Did you have a fuel line disconnected?
The fuel pump is only activated when the engine is turning. That's why the fuel didn't shoot out until you cranked it over.
Oh yeah :) Gonna have to air it out for sometime now lol. Had to be sure

Disconnect the end of the wire from ground and splice it onto the black/orange wire at the fusebox connector, as shown in my earlier photo (post #17).
Awesome,

I will do that, Thank you very much for your help!
 

·
Registered
Joined
·
10 Posts
Not sure who you are, but I definitely owe you a beer or two. You saved me a few hundreds for sure.

Thank you for taking your time to answer, provide clear instructions with pictures.

Much appreciated,

It purrs as it once did before.
 

·
Registered
Joined
·
4 Posts
Happy I was able to help. And it's good to hear that my workaround worked.
Hi Autospark.

I got this hyundai tucson 2006. My car doesn't start but crank. But if i switch the ignition switch and at the same time press the gas pedal the engine will start but when i release my foot on the pedal the engine dies. When i re start it again ( foot on the pedal while switching the ignition) then if i hold my foot on the pedal for about 5 minutes then release my foot on the gas pedal the engine continue and don't die. I am not good in car so i am asking what should i check. Is it relay related, fuel pump or air intake.?
 

·
Registered
Drives : Nissan NV200 Flies : Rans S6ES
Joined
·
14,734 Posts
Is it relay related, fuel pump or air intake.?
Assuming it's a petrol engine my guess would be air intake related, since your holding the throttle valve open with the pedal which will allow more air into the inlet. You might want to remove the idle control valve and clean it out with some carb cleaner to see if that helps.

448388


If I helped you fix it, why not...

Your support is greatly appreciated
 

·
Registered
Joined
·
4 Posts
Assuming it's a petrol engine my guess would be air intake related, since your holding the throttle valve open with the pedal which will allow more air into the inlet. You might want to remove the idle control valve and clean it out with some carb cleaner to see if that helps.

View attachment 448388

If I helped you fix it, why not...

Your support is greatly appreciated
You are a heaven sent sir AutoSpark. Dis assemble idler control valve. I can't imagine how much carbon were accumulated on the internal assembly. Cleaned it with throttle cleaner and installed it back. Voila! One click and it start. Idle RPM on the gauge is around 1000rpm. But i am still not satisfied as a check engine appear on the dashboard and the needle on the rpm gauge still fluctuates a little bit. But the good thing my car starts now.
 

·
Registered
Joined
·
4 Posts
You are a heaven sent sir AutoSpark. Dis assemble idler control valve. I can't imagine how much carbon were accumulated on the internal assembly. Cleaned it with throttle cleaner and installed it back. Voila! One click and it start. Idle RPM on the gauge is around 1000rpm. But i am still not satisfied as a check engine appear on the dashboard and the needle on the rpm gauge still fluctuates a little bit. But the good thing my car starts now.
Enjoy your coffee sir Autospark. I have put in $3 for you. See yah!
 

·
Registered
Drives : Nissan NV200 Flies : Rans S6ES
Joined
·
14,734 Posts
Enjoy your coffee sir Autospark. I have put in $3 for you. See yah!
Thank you very much. Great to hear the engine is running properly again.

If I helped you fix it, why not...

Your support is greatly appreciated
 
21 - 38 of 38 Posts
Top