Posted: 11/30/2014 7:19:08 PM EDT
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Have a cheap Chinese relay for a fuel pump. Wired such that fuel pump only comes on when there is sufficient oil pressure, and during cranking.
Today I noticed something very weird. I turned key one click forward(prior to start slot) and I heard a noise, which I am certain was the fuel pump receiving power. My question is how in the world would that be possible, given that I have no provisions built in for a priming cycle? My only thought is that perhaps the relay is letting current pass internally, or is on its way out. I've tried to replicate the issue multiple times, and was unable to. Just happened the one time at first start of the day. Thanks guys. |
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Quoted:
How long did the pump come on for? Most fuel injected vehicles I've worked on will prime the system when the key is turned to run. Maybe you couldn't get it to replicate because the pressure hadn't bled off? I know for certain the pump was receiving power, because I previously had my system setup to run whenever the key was on start(one click before run) as well as while running. This system is aftermarket with no provisions for priming the pump. Just running/cranking power. My only thought is that the relay was letting power across and is on its way out. I have not been able to replicate it, and just don't want to get stranded if I can go ahead and install a new relay now. |
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Quoted:
Relays will weld themselves closed, if it's a typical black "ice cube" relay I'd keep an extra on hand just in case. Yeah exactly my thought on that. I anticipate it started to stick and then released itself. Either way its on its way out and should be replaced. Got a nice made in USA waterproof one to go in. Glad I wasn't too far off on my initial diagnosis because it was my only idea. 
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