Fuel pump not working fuse block shows no voltage

Tiny
CA7922303
  • MEMBER
  • 2001 HYUNDAI SANTA FE
  • 2.7L
  • V6
  • 2WD
  • AUTOMATIC
  • 300,000 MILES
Fuel pump check on engine bay fuse block shows no voltage. Can hear the usual what I thought was fuel pump when key is turned to on. All fuses, relays are good. Will run with starter fluid. Could it be fuel cutoff switch next to master cylinder? Changed fuel pump.
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Wednesday, February 5th, 2020 AT 12:44 PM

19 Replies

Tiny
KASEKENNY
  • EXPERT
If you take a look at the wiring diagram, are you saying that you do not have voltage on the fuel pump check connector in the junction block? If that is what you are checking then you have an issue with the fuel pump relay, ECU fuse, engine control relay or the fusible link. Basically we need to start checking for power on each of these until we find where we have power. Then the item just downstream of that is the issue.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit
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Saturday, May 8th, 2021 AT 10:13 AM
Tiny
CA7922303
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I checked again and I do have voltage at the fuel pump checkpoint engine bay fuse block.
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Saturday, May 8th, 2021 AT 10:13 AM
Tiny
CA7922303
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After installing inertia switch from pull apart off of a 2004. Or I had a bad connection when I checked it previously?
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+1
Saturday, May 8th, 2021 AT 10:13 AM
Tiny
KASEKENNY
  • EXPERT
So everything is working or you still have no fuel pressure?
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Saturday, May 8th, 2021 AT 10:13 AM
Tiny
CA7922303
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No fuel pressure.
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Saturday, May 8th, 2021 AT 10:13 AM
Tiny
CA7922303
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Correction: fuel pump only comes on when I jump relay posts. When I install good known relay and turn key on, pump does not come on. Bought 2 fuel pumps from pull apart junk yard and both bench test good. Any ideas on why I can jump pump but will not operate with good relay?
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Saturday, May 8th, 2021 AT 10:13 AM
Tiny
CA7922303
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I'm driving vehicle now and it seems to have an intermittent lack of fuel issue. Can be hard to start and or cut out on going into gear or acceleration sometimes. Mechanic briefly commented that it appeared to maybe be getting too much fuel.
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Saturday, May 8th, 2021 AT 10:13 AM
Tiny
KASEKENNY
  • EXPERT
Okay. We need to get the actual fuel pressure when the key is turned on and then when it is running and you feel this cutting out. I would just tape it to the windshield so you can sit in the car and see the pressure.

I doubt it is the pump but we need to see what the pressure is to determine if it is even related to the fuel pressure.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator
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Saturday, May 8th, 2021 AT 10:13 AM
Tiny
CA7922303
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Fuel pump relay sockets with key on read 30-12v, 87-0v, 86-0v, 85-12v.
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Saturday, May 8th, 2021 AT 10:13 AM
Tiny
KASEKENNY
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Sorry for the confusion. If the vehicle starts, we need to monitor the pressure with the key on and then with it running. Take a look at the attachments and let me know what the actual fuel pressure is and we can go from there.
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Saturday, May 8th, 2021 AT 10:13 AM
Tiny
CA7922303
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Key on (actually fuel pump relay jumped) looks like 25 kPa, running looks to be at least 60 kPa?
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Saturday, May 8th, 2021 AT 10:13 AM
Tiny
KASEKENNY
  • EXPERT
Is there a chance that this was PSI and not kPa? Or was there a scale on the gauge? If this was PSI then it will make sense that the pump is not building pressure at key on. This could be due to a leaking injector.

To test this, do a couple key cycles and then pull the plugs and see if they smell like fuel. If they are fouled, this will be another indicator of a leaking injector.

This would also line up with what the other mechanic mentioned that there was too much fuel.

Let me know and we can take next step. Thanks
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Saturday, May 8th, 2021 AT 10:13 AM
Tiny
CA7922303
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2 psi key on, 10 psi running.
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Saturday, May 8th, 2021 AT 10:13 AM
Tiny
KASEKENNY
  • EXPERT
You have a vacuum operated fuel pressure regulator. That means if you disconnect the hose while the engine is running the pressure should jump to about 50 PSI while it is running. If it does, then your regulator is good.

However, your pressure is low. That means we have one of three main things.

1. Weak fuel pump - you already replaced this so let's assume that is ok since you changed it and it did not change the issue. Correct?
2. A clogged fuel filter preventing enough fuel from being delivered to the rail - unfortunate thing is the filter on your vehicle is part of the pump so as long as you changed the entire assembly and not just the pump portion, then that is not the issue either. (You would know this if you had to move parts over from the old pump to the new one, or did you just take the entire fuel pump out and put the new one in? See attachment 4, the three main parts of the pump assembly are circled)
3. Leaking injectors not allowing the pump to build pressure - this is where we need to cycle the key a few times and then check plugs for fuel.

Let me know what you think. Thanks
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Saturday, May 8th, 2021 AT 10:14 AM
Tiny
CA7922303
  • MEMBER
Changed fuel pump to another used one that bench tested good and a new sock filter. Replaced #6 fuel injector with used fuel injector from an 06 2.7. Seems to idle better. Will have to check fuel pressure first chance I get to rent one from parts store. Appreciate your help.
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Saturday, May 8th, 2021 AT 10:14 AM
Tiny
KASEKENNY
  • EXPERT
Sounds great. I imagine your pressure will be improved. If still not up to where it should be we may have other injectors leaking. Just make sure you keep track of if the vacuum is on or off. It will change the pressure. I attached the reading and vacuum line location of the regulator again in case you need it. Thanks
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Saturday, May 8th, 2021 AT 10:14 AM
Tiny
CA7922303
  • MEMBER
Check engine light came on. Don't know why now? AutoZone shows codes p0265, 0271, 0227, 0335, 0113, 0118, 0102, 1529, 0740, replaced a few days ago: fuel injector #6, mass air flow, idle air speed, sensor next to idle air speed(don't know name of it), camshaft sensor and knock sensors where replaced awhile back from pullapart and crankshaft position sensor was replaced with new one from Amazon. Haven't been able to find a good way to splice into supply line of fuel system to test it. There is no port. Any ideas? Thanks for your help.
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Saturday, May 8th, 2021 AT 10:14 AM
Tiny
CA7922303
  • MEMBER
Took vehicle by an auto shop that Napa auto parts refers people to and was told that there is no good way to splice into the high pressure supply line at the fuel rail without damaging line. Do you have any suggestions? Thanks for your help.
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Saturday, May 8th, 2021 AT 10:14 AM
Tiny
KASEKENNY
  • EXPERT
I attached the process on how to measure the fuel pressure. There is a tool that is needed that splices into the fuel supply line. Basically you unbolt the line and put this inline. However, they are correct that there is no easy way to do it. How did you get the pressure readings that you provided prior?
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Saturday, May 8th, 2021 AT 10:14 AM

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