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No ECU or Fuel Pump Power

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Old Nov 14, 2011 | 04:43 PM
  #1  
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Default No ECU or Fuel Pump Power

Car was running fine, actually just got it back together, ran fine and made great power on the dyno. That was about 2 months ago now. Been driving it lightly ever since. Last week I didn't have time to drive it so I went out to start it just to let the battery charge for a bit and whatnot. I started it, it ran for about 30 seconds stalled and threw a CEL. I said whatever and left it because I was going to work on it over the weekend.

So I'm having a weird issue with the car now all of a sudden
Ignition gets key on power. But fuel pump won't prime and ECU doesn't get power.
Replaced main relay and ignition switch to no luck. No blown fuses either. Tested all fuses with a test light and all were OK. Pulled out the
multi-meter, tested all connections and all seems well there too.
If I jump connectors 5 and 7 on the main relay the fuel pump primes.


Car will still crank however since the pump doesn't prime there is no
fuel pressure and no fire...

Anyone encounter this?
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Old Nov 14, 2011 | 05:13 PM
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Default Re: No ECU or Fuel Pump Power

The fuel pump works because you are supplying power directly to it when you jump the terminals.

There are a few things to check, the first thing is to make sure you have all three (3) powers at the PGM-FI Main Relay, if it's the 93 Integra...

Yellow/white, 12V+, hot at all times, fuse 38 -10A, engine bay fuse box.
Black/yellow, 12V+, hot in run and start, fuse 24 - 15A, under dash fuse box.
Blue/white, 12V+, hot during cranking to start only, fuse 18 - 7.5A, under dash fuse box.

Unplug the PGM-FI Main Relay and test for the above powers, this applies to all Honda/Acura with PGM-FI fuel injection, wire colors will differ and locations may also, but all 3 powers must be there.
You can also check to see if you have power at the injectors, [yellow/black leads] and at IPG1 and IPG2 at the ECU/ECM, only two yellow/black leads to the ECU/ECM, ign. switch must be on. 94
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Old Nov 14, 2011 | 05:39 PM
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Default Re: No ECU or Fuel Pump Power

Thanks for your response, yes the 93 Integra.
Yes just pointed out the pump works in case someone wanted to mention that it was the pump.

I pulled readings the other night but had no idea what the baseline readings were supposed to be. Looked them up in All Data and need to go back out and check.
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Old Nov 15, 2011 | 04:16 AM
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Default Re: No ECU or Fuel Pump Power

Guess since I am stumped right now I have to take a break on it for a few days. Going to pull the battery and charge it so it won't die on me.
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Old Nov 15, 2011 | 04:54 AM
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Default Re: No ECU or Fuel Pump Power

What was the CEL?
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Old Nov 15, 2011 | 05:32 AM
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Default Re: No ECU or Fuel Pump Power

Originally Posted by grumblemarc
What was the CEL?
Well weird thing is that the CEL is very faint so I am not sure if it is actually on or now. All other dash lights illuminate fine.
I can't connect through the ECU since there is no power to pull code through Hondata and I need to work through the wiring to find where the jumper wires are to try and jump it. But I just assumed since it seems the ECU doesn't get power this was light up to indicate a communications issue with the ECU itself?
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Old Nov 15, 2011 | 06:11 AM
  #7  
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Default Re: No ECU or Fuel Pump Power

There are four (4) 12V+ powers for the ECU/ECM...
1-blue/white, hot during cranking to start only, fuse 18 - 7.5a, in under dash fuse box.
2-white/yellow [or white/green], hot at all times, fuse 34 - 7.5A, in engine bay fuse box.
3-and 4-yellow/black are from one source, the PGM-FI Main Relay, [injector relay] fuse 38 - 10A, hot at all times, but switched through the injector relay.

Which one/ones of the above do not have power, [check at ECU/ECM with ign. switch on]? 94
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Old Dec 1, 2011 | 06:12 PM
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Default Re: No ECU or Fuel Pump Power

Ok so I found 2 issues. The Realys I was using were bad.
The thermo ground was also bad.

Fixed and running perfectly!
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Old Jul 5, 2024 | 08:24 AM
  #9  
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Default Re: No ECU or Fuel Pump Power

Originally Posted by Mattb16teg
Car was running fine, actually just got it back together, ran fine and made great power on the dyno. That was about 2 months ago now. Been driving it lightly ever since. Last week I didn't have time to drive it so I went out to start it just to let the battery charge for a bit and whatnot. I started it, it ran for about 30 seconds stalled and threw a CEL. I said whatever and left it because I was going to work on it over the weekend.

So I'm having a weird issue with the car now all of a sudden

Ignition gets key on power. But fuel pump won't prime and ECU doesn't get power.
Replaced main relay and ignition switch to no luck. No blown fuses either. Tested all fuses with a test light and all were OK. Pulled out the
multi-meter, tested all connections and all seems well there too.
If I jump connectors 5 and 7 on the main relay the fuel pump primes.


Car will still crank however since the pump doesn't prime there is no
fuel pressure and no fire...

Anyone encounter this?
same issue over anover and find why
Reply
Old Jul 8, 2024 | 07:24 AM
  #10  
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From: Dillwyn va
Default Re: No ECU or Fuel Pump Power

i had same problem with my eg and turns out it was my ecu.. And my car was sitting for a min... Before i put my motor back in.. and thats what it started doing when i got it back together..
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