gertie3993

iTrader: (2)

Hey guys,

I'm running the HP EFI system on my lq4 swap. Each night I've been disconnecting the computer wires from the battery because the fuel pump has been kicking on and draining my battery. Today when I reconnected the wires the starter cranked but the engine just would not start. I can hear the fuel pump and injectors prime when I first turn the ignition to on. The fuel pressure sensor is telling me that the pressure at the rail is normal. I read that it could be a cam or crank sensor issue but I am getting an rpm reading when the engine cranks so I don't believe that's the case. The fuse between the battery and relay checked out fine. I also figured since I've been trying to start it a lot today the engine might be flooded. I pulled a spark plug and it was completely dry. It was running great last night so I'm not really sure what would've changed since. Any help would be appreciated. Thanks

92BLKL98

As an electronics tech on large jet aircraft I can say that what you've been doing is detrimental to the PCM. You have quite possibly corrupted the software in the computer. These PCMs have a reason they are kept on the hot battery bus on the car. You would be better off to have disconnected the pump relay. Look at it this way, When is the most frequent time you blow a light bulb? When you first energize it. The initial cold load shock (highest current draw) happens on initial start up of any electrical device. I hope you have not damaged your PCM but ya never know. Seems like someone once said on this board (maybe Pocket) that the cam sensor is only used for start up. Could be that, but I would definitely stop de-energizing the PCM and then re-energizing it.

gertie3993

iTrader: (2)

Ok, I'll make sure to stop doing that then. I didn't think it would make a difference as long as the ignition was off and it wasn't drawing power. Thanks for letting me know

92BLKL98

Sounds like you have a nice build, I hope you get it running again. I'm just now working on mine.

QwkTrip

iTrader: (22)

Interesting... Another Holley HP with a fuel pump that won't shut off. You're not the first.

Wire red fuel pump power to a switched battery source, not a constant battery source. This is one of multiple areas where the Holley directions should not be followed. In reality there is likely some kind of deeper problem with the Holley logic, or a ground loop issue with the ECM drivers but good luck solving that. You can always talk to Danny at Holley HP forum and see where it leads, but my method is common best practice regardless of what Holley instructions say.

While you're at it get the injectors off constant battery too.

gertie3993

iTrader: (2)

I'll have to move it to switched power. What I don't understand is why it worked fine for a while and then started acting up again.

Do you have any ideas why the injectors wouldn't pump fuel? There's a possibility I'm not getting spark either, so I'm thinking maybe the relay.

cypris09

iTrader: (1)

Check your grounds. Also get a noid light to see if the injectors pulse And see if you're getting spark. Always good to start off with the basics and go from there

QwkTrip

iTrader: (22)

What I am suggesting is not the root of your problem. It is just an improvement that will keep you from being stranded somewhere with dead batteries.

I'm not sure how to help with your current problem other than suggesting you go over to the Holley HP forum and talk with Danny. He is a really smart fellow.

gertie3993

iTrader: (2)

I had a few minutes to continue looking at it and I noticed the relay has no cover. Actually I don't think it even did when I bought it but it looks like there's some rust coming out the bottom of the relay. I removed it and the contacts seemed fine. When I reconnected it the car it started but died shortly after so I'm thinking that may be the problem.

gertie3993

iTrader: (2)

Good news, I figured it out. The relay went bad. I was able to open the relay and found that there was a coat of rust over everything. I used a wire brush to clean it off and when I did I noticed that one end of the resistor broke away from the solder. I resoldered the ends of the resistor within the relay and reconnected it. I also relocated the fuse and relay to the inside of the car. Car fired right up.

I think that may have also solved the problem I was having with the fuel pump. I'll continue checking it throughout the day to make sure. If it kicks on again I'll add a switch or tie it into a switched power source.

Thanks again for all the help

92BLKL98

Great glad you figured it out and the PCM is OK.

cypris09

iTrader: (1)

Glad it was something simple. If I were you I'd keep a spare relay jic it does this again.

gertie3993

iTrader: (2)

For anyone else with the holley efi system, I found out today that the main relay in the harness has an optional weatherproof relay. The original relay doesn't have a cover, instead its setup just in case you want to upgrade to the linked weatherproofed relay.

http://www.lsxtune.com/shop/product_...roducts_id/671