Guys, here's what I have.
New Holley HP ECU controlling the action through the stock relay, activating a Racetronix pump and hotwire kit.

So here's what I've tested and what's going on. First, when I jump the relay through the ALDL port, the pump works just fine. 12v through the red wire, which doesn't have to switch the relay, straight through the circuit, showing 12v on the other side of the relay, and as I said, pumps just fine.

However when I turn the key, I'm getting 12v from the Holley unit for a seconds to prime, as I should, and I have 12v going IN to the relay via the always hot orange, but I'm only getting 5 or 6 volts on the other side of the relay going to the pump.

Sure seems obvious....like the switch isn't switching. I guess what's throwing me is that it IS showing some voltage. I guess I had expected on or off. I can visualize how I'm getting "some" voltage. Like it should be on or off!?!? Right?

Thoughts? ...and if it's a relay....where should I look to buy one? Just google it?

 

For the record, I ASSUME the ground is good. I didn't check it. Kinda put everything in the cold garage away for the night. I'll check it tomorrow. ...but it should be good....and like the said, the "red" side worked just fine...it's that switched side....

 

i found this link helpful for relays.
87a throws me for a loop sometimes.
http://www.rattlebars.com/mtz/basicrelay.html

 

Voltage drop across the relay is caused by resistance internal to the relay. Sounds like the relay contacts are toast.

By the way, those stock relays are a terrible design and a fire hazard. Best thing you can do is eliminate the stock relay and replace with a modern relay.

 

That's a pretty good explanation. Doesn't necessarily help me in this case, but a good read none the less.

...and the 87a makes perfect sense in my case. (fuel pump relay). That pin has a red wire on my 89 and is connected to the "G" port I believe in the ALDL.

 

do you think maybe you have 87 and 87a wired backwards possibly?

 

The 87 and 87a both deliver voltage when they should, it's just that the 87 doesn't deliver enough. It's losing power somewhere. 12v in, only 6v out. As Qwktrip mentions:
That's what's happening, so I assume his diagnosis is accurate.

...so....I'm not an electrical wizard, and sometimes it takes me a little while to put it all together. ...I'm running the racetronix hotwire kit, which has it's OWN relay. All the factory relay is really doing is switching the new Racetronix relay. That being said, i don't NEED the factory relay, bad or not. I'm going to bypass the old relay altogether. That "should" work. Going to see Star Wars now though....I'll have to try it out later!!!!

 

This thread interests me.

Please report on outcome of deletion of factory fuel pump relay.

Cheers!

 

Well it works. Kind of. ...it pumps great, but won't stop running like it's supposed to after a few seconds. .....gonna jump over to the Holley board and see what is supposed to stop the priming.

 

No experience with non-OE EFI, but generally the OE setup energizes the fuel pump briefly to prime the system, then it switches off until it receives an ignition pulse from the ICM.

 

That is correct. You are coming to the same conclusion I did when I installed Holley HP EFI.

I don't know which Hot Wire kit you purchased, but I'm guessing the relay is back by the fuel tank. If so, then connect the Holley fuel pump wire to the TAN/WHT wire on your car. That TAN/WHT wire is the original B+ power for the stock fuel pump. It is already conveniently plumbed through the firewall, down the drive side door sill, and out thru the 3-pin connector at the rear firewall. Use that wire to operate the Racetronix fuel pump relay. If you need a replacement mating connector at the rear firewall, the part number is 12020829. I just saved you a week of research trying to find that part number.

If you bought the 4th gen LS1 Hot Wire kit then this is how it is wired. See post #188

https://www.thirdgen.org/forums/ltx-...ml#post5825643

If you feel a little ambitious then you can simplify it further. That kit has extra wiring on top of the fuel tank to make it plug-and-play into a 4th gen car. That extra harness is just extra baggage for you and can easily be eliminated with some side cutters and a bit of wire solder. See posts #249 and #250.

https://www.thirdgen.org/forums/ltx-...ml#post5893401

If you feel really ambitious then you can totally de-construct the Hot Wire kit and move the fuel pump relay to underhood and run all the wiring through the interior of the car. That is what I did. See post #269 and #299.

https://www.thirdgen.org/forums/ltx-...ml#post5900834

https://www.thirdgen.org/forums/ltx-...ml#post5961350

 

The time of fuel prime is controlled in the HP EFI software. Go to the System Parameters window and you will see a setting for "Fuel Pump Prime" where you can change the time. 3 to 5 seconds is fine.

That same window will have a checkbox called, "Enable Fuel Prime" that will enable/disable a "Fuel Prime Percent" box. If you have a cam & crank speed sensor then Holley will not inject any fuel until the timing is synchronized and it knows firing position. This can take a few seconds and cause slow starts. Enabling the checkbox will cause the engine to run in batch fire mode at beginning of crank cycle, before the speed timing system is synchronized. This can help the engine fire up quickly and overcome the delay of starting. Usual settings are 100% - 200% of the startup enrichment fuel map. I use a value of 125% and it works well and doesn't over fuel the engine during a warm engine restart.

If you have a batch fire fuel system then just leave the checkbox off.

 

Qwktrip. LOT of info. Thanks.

First...I DO have the green Holley trigger wired to the tan/white wire.

Pretty sure I read over on Holley that Danny said the relay itself induces the 5 second prime when triggered. That doesn't totally make sense, and I may have read it wrong.

I'm currently running "paired" as my injection strategy, and my "prime enable" is unchecked. Does this matter? ...this is first go...I'm learning...

thanks,
Chris

 

A relay is just a device that follows orders to turn ON and OFF. Has no ability to do anything intelligent on it's own. The fuel prime is controlled by the Holley ECM only. Are you sure the relay and fuel pump are wired right? Are you using a fuel pressure sensor?

I don't know what is a "paired" strategy. I'm guessing you have a small block Chevy with a distributor and I can't help you with that. I only know the LS platform.

 

It was suggested to leave paired to start. I think instead of one "batch" fire, you get two "paired" firings of the injectors.

Am I SURE it's wired properly? Well...no. LOL. ....the kit was pretty straight forward though, not really anything custom on my part.

So this is interesting.....with a multimeter, I can see the ECU triggering the relay with 12v for a few seconds (prime) and then I hear a faint click from the ECU, and it drops to 3.5v, although the pump keeps running. If I disconnect the wires, the pump stops. If I reconnect, it does NOT start running again. It's as if that 3.5v can keep the relay "on", but can't TURN it on if already off.

 

Any relay has a "pull in" voltage where the relay finally turns on, and a "drop out" voltage where it turns off. The drop out voltage for the relay is likely below 3.5V so that is why the relay is still engaged at 3.5V.

If the ECM driver turns off (disabling the fuel pump) then there should be 0V at the output terminal of the ECM -- period! You either have another power source tied into that fuel pump circuit, or maybe the main ECM ground is really poor.

The other possibility is the ECM is defective but I'd probably bet on your wiring job being the problem for now. How exactly did you wire up everything? Drawing things out the way I did helps a lot.

 

IDK about the holley set up, but your fuel pump should stay running if your getting power from your oil pressure switch, even if you disconnect the relay.

theres a diagram at about 40 seconds into this video that "might" be helpful? i know it's not for holley, but shows a basic wiring diagram and how it should work.

 

So, ultimately my problem turned out to be a bad ground. 2 hours with a multimeter told the tale. ....Holley ECU is connected directly to the tan/white wire, bypassing the OE relay, and now directly triggering the Racetronix relay. Pump comes on and primes as it is supposed to, then shuts off.

That being said, there is still some residual voltage from the ECU AFTER it has stopped priming. Danny over the Holley board said this sounds normal, although he didn't specify exactly which ECU functions dropped to dead 0v, and which didn't. ...anyhow...at this point, everything is operating as expected.

Thanks guys

 

Oil pressure switch is long gone, lol.

 

Glad you got it sorted out.

You've lost a few basic functions the stock ECM used to manage for you. If you need some help figuring out how to operate radiator fans, AC, speedometer, and transmission reverse lockout, then let me know and I can help. I took a more advanced approach than what you'll read in the Holley manual. I'm pretty dumb when it comes to tuning, but pretty smart when it comes to using those custom inputs and outputs.

 

Well I haven't had AC for a LONG time. It was never intended to be a DD, and if I can't have the TTops out, I'm probably not driving it. ....Radiator and fans are being controlled by a Painless Wiring F5 kit, Speedo on my 89 is still mechanical, and well...you're right about that reverse lockout. It's a TKO, and you'd REALLY need to miss 4th gear to drop it "R".

As for the rest of my day...I Got it running!!!!!
check out youtube or my FB page in the sig.