Aftermarket fuse and relay junction block

[Matthew Jeschke]

I desperately need some sort of aftermarket fuse junction block. It should be weather sealed.

I've been tracking gremlins in my fuel system. The pump has intermittent performance. I tracked it down to overheating relays and fuse block under the hood. My fuel pump is aftermarket which runs at 11 AMPS... Around 140 watts KOEO. I bought a few parts to try and make a bridge gap till I could find a better solution. I jumpered the junction block PCM signal to an external relay and wired it up to bat positive with a fuse and spliced into the wire to the pump. I digress though... It worked until the PCM overloaded. I was driving and the PCM just turned off. I had to remove my jumper, put in the original relay in the junction block... then cycle the key a few times. The PCM finally booted and I was able to start the truck. However, using the fuse block aggravates my problem with junction block overheating and the pump stops working.

Long story short, I desperately need a solution that's weather sealed (for under hood), has a relay and fuse that I can wire up to bypass the junction block reliably. Been searching the internet and see lots of chinesium junction blocks on Amazon marketed for boats. Maybe a weather sealed relay with harness I can splice a fuse into? Any ideas?

 

[Matthew Jeschke]

I found this page here... https://lt1swap.com/wiringharness.htm

Still in need of some sort of rugged, weather hardened setup for the fuel pump fuse.

I may also need to rewire the entire engine compartment. Harness is 24 years old and showing it's age.

 

[Rocket Man]

Why not put in a stock fuel pump? Or are you running 800 hp or something?
Also, why would it need to be weather sealed when your stock fuse block isn’t? Just don’t hose it down when you pressure wash under the hood.

 

[Matthew Jeschke]

The 140 LPH pump is at the cusp of what my build is at. Plus I got about $300 into the aftermarket pump and don't want to drop the tank again if I don't have to.

Last time truck stalled I'm unsure if it was due to pump or something else. I think the ignition shut off. When I went to cycle the key I didn't get a check engine light indicating the PCM had booted but the truck started. Really confused.

 

[Rocket Man]

The 140 LPH pump is at the cusp of what my build is at. Plus I got about $300 into the aftermarket pump and don't want to drop the tank again if I don't have to.

The stock pump is good to about 600HP iirc. I have a blower and cam on my 6.0 in my 02 Denali and the stocker is fine. Seems easier to go that route rather than doing what you’re trying but it’s your truck obviously. Dropping the tank isn’t hard, just remove the fuel first. Sounds like you have a headache going on. I like to keep things simple. Also, wiring harnesses don’t tend to go bad so I see no need to rewire the entire engine bay, that also sounds like it would be asking for trouble. I can see replacing the split loom but that should be it. Good luck with whatever you decide.

 

[Joseph Garcia]

I desperately need some sort of aftermarket fuse junction block. It should be weather sealed.

I've been tracking gremlins in my fuel system. The pump has intermittent performance. I tracked it down to overheating relays and fuse block under the hood. My fuel pump is aftermarket which runs at 11 AMPS... Around 140 watts KOEO. I bought a few parts to try and make a bridge gap till I could find a better solution. I jumpered the junction block PCM signal to an external relay and wired it up to bat positive with a fuse and spliced into the wire to the pump. I digress though... It worked until the PCM overloaded. I was driving and the PCM just turned off. I had to remove my jumper, put in the original relay in the junction block... then cycle the key a few times. The PCM finally booted and I was able to start the truck. However, using the fuse block aggravates my problem with junction block overheating and the pump stops working.

Long story short, I desperately need a solution that's weather sealed (for under hood), has a relay and fuse that I can wire up to bypass the junction block reliably. Been searching the internet and see lots of chinesium junction blocks on Amazon marketed for boats. Maybe a weather sealed relay with harness I can splice a fuse into? Any ideas?

I suggest that you go to a local quality car/truck audio shop and see what they have. They have all kinds of high amperage power and distribution blocks, including water resistant ones.

 

[Matthew Jeschke]

I have a pretty good idea of what might be happing now after I've had time to sit down and stop freaking out.

The PCM is powered by the same fuse as the fuel pump. I've jumpered a fuel pump relay to outside the factory junction block.

It dawned on me, the same fried / damaged circuitry that previously powered the pump is still powering the PCM *sigh*. I likely need to find a replacement junction block.

So often I answer my own questions but cannot say how much I appreciate the conversation here and help reflecting on what maybe causing my trouble.

The stock pump is good to about 600HP iirc. I have a blower and cam on my 6.0 in my 02 Denali and the stocker is fine. Seems easier to go that route rather than doing what you’re trying but it’s your truck obviously. Dropping the tank isn’t hard, just remove the fuel first. Sounds like you have a headache going on. I like to keep things simple. Also, wiring harnesses don’t tend to go bad so I see no need to rewire the entire engine bay, that also sounds like it would be asking for trouble. I can see replacing the split loom but that should be it. Good luck with whatever you decide.

@Rocket Man thanks for chipping in. Hate to say I have several hundred dollars into the new pump. Sadly I'm familiar with the tank dropping procedure. I could do it blindfolded now I've done it so many times.

Are you sure your pump is 140LPH from the LM9/LQ9/LQ4 motor? I did calculations and that's good for roughly 400 HP...? There must be more than one factory pump part number?

Fuel Pump Calculator

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fuelab.com

I guess in hindsight, I'm probably not making quite 400 HP yet but with some more tuning I should be coming up on it fairly soon. My setup is an LQ9 / 6.0L. I think it should be able to do similar numbers to the 400HP LS2, especially with my cam?

My ultimate goal if I could come across some $$ and not be a constant poor boy, is to install AFR Mongoose heads. That'd bump my power up well into the 400 HP range.

I suggest that you go to a local quality car/truck audio shop and see what they have. They have all kinds of high amperage power and distribution blocks, including water resistant ones.

GENIOUS. I didn't even think of looking through car stereo stuff! All the parts coming up are for boats.