C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

84 C4 Fuel pump relay problem.

Old 01-26-2015, 09:47 PM
  #1  
rnoswal
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Default 84 C4 Fuel pump relay problem.

I have a problem getting any power to this plug. None show voltage ever except the middle pin which only blips my test light when I turn the key on. There are 2 reds connected on the right, then black, Green, single red then yellow. If these pictures show up and anyone has any suggestions on where I might be losing the voltage please let me know.

I checked the fuse panel and all the fuses that have power work on both sides. Is there another possible fuse I might be missing somewhere else? I have a new fuel pump and relay. If I hot wire the pump, it does work. I did order a service manual cd with wiring so I hope to trace the wiring with that. I have a chiltons but that is no help.

This is all I need to get the car running for the first time so I am kind of anxious.

Thanks

Russ








Old 01-27-2015, 12:06 AM
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ccrazor
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If you look by the battery there are two fusible links, one for the fan, the other marked C341. C341 supplies power to the fuel pump relay and the oil pressure switch on orange wires.. The blip you get is the 12v you get to operate the fuel pump for its two second prime from the ECM..







Last edited by ccrazor; 01-27-2015 at 12:29 AM.
Old 01-27-2015, 02:18 AM
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Hot Rod Roy
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Russ, that relay connector looks like toast to me. The two red wires to the connector is pin A in the diagram. These two red wires should be connected together. Are they? Even if your connector and the relay were bad, the car should start after a long enough crank to build oil pressure, if the red wires have continuity (and your fusible link is good).

Did you verify the fuel pump fuse (marked FP, bottom row, fourth column), is good?


Last edited by Hot Rod Roy; 01-27-2015 at 02:23 AM.
Old 01-27-2015, 01:39 PM
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rnoswal
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That was it! The C341 plug. I had it plugged into something else that didn't burn up fortunately. When I plugged it into the right connector and turned the key on, I could hear the pump. I turned the key and it fired right up! Still smiling. Roy, you were right about that plug looking pretty bad. I pulled each wire, slipped a heat shrink wrap on each one so no wires were exposed. I could see a short at best happening there and a fire at worst. Thanks for the heads up and motivation to fix that part.

I still have to break the cam in so didn't run it much. I still have to get the heater control piping on the passenger side under the hood, the car was missing a lot of stuff. Then hook up some hoses and fill it with water. I also discovered a transmission coolant line leaking pretty bad so have to fix that too.

Thanks again guys.

Russ
Old 01-27-2015, 04:17 PM
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86C4Z51
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Wow Hot Rod and Razor, nice posts. +1 to both of you.
Old 01-27-2015, 06:37 PM
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playsdixie
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Originally Posted by 86C4Z51
Wow Hot Rod and Razor, nice posts. +1 to both of you.
great job.....my vette runs sweet as sugar thanks to the advise on this forum....

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