Thanks Santa (the neverending trials of the 400,000klm, 400kw, RB30, manual swapped Stagea)

[Duncan]

So, a few posts back I mentioned the fuel pump fuse holder had melted/failed. Was driving up a hill on a hot day not far from home the other week and once again the unicorn failed to proceed.

Had a good look, and the new fuse holder I had added had also melted. These 525 fuel pumps clearly are continuous, high current beasts.

That is a 30a fuse (not blown) in a 30a rated fuse holder. Holder is so badly melted that it was loosing electrical connection.

The areoflow web page shows the pump pulling up to 16 amps, then unhelpfully states "This fuel pump requires a minimum 35-amp relay on each pump, along with suitable gauge wire and fuse/circuit breaker".

https://aeroflowperformance.com/af49-1057-525lph-e85-hi-flow-fuel-pump

"Suitable", eh? Can't say that is exactly a specification.

[Duncan]

So given that the 30a rated holders that everyone sells (even the pricey narva stuff is 30a rated) weren't doing the job, I grabbed one of these, a Blue Sea 4 circuit standard fuse holder

https://www.bluesea.com/products/5045/ST_Blade_Compact_Fuse_Blocks_-_4_Circuits

There are a bunch of fakes on ebay too at about 1/3 of the price but I went genuine as I don't need further quality issues.

Bluesea rate it to 100A max with 30A max per circuit. I am running 25a for the fuel pump, 15a for the stereo amp, 10a for the LED light bar and 10a for the aux reverse lights so well within it's rated level.

Some minor mods were made to remove the supplied power stud and replace it with a M6 bolt that runs through the back of the holder as the power supply from the battery is routed inside the fuse box. I then mounted it to the side of the fuse box with m4 bolts in the space between the fuse box and plenum.

I took the opportunity to label those 4 power supply wires too, using motorsport spec masking tape and sharpie marker. There are still 2 other mystery wires attached to the battery +, one of which is running though some sort of circuit breaker (maybe the trailer electric brake)? Too many people have had their hands on this car over the years....

The only thing I'm not too happy about is that they use screw in terminals, I've stayed away from them in the race car, will be interesting to see how they go in a hot/bumpy environment over time. I have secured the wires to minimise the amount of movement.

 

[MBS206]

It's annoying it's melting the fuse holders, and it's really crap that even the good manufacturers, while they will rate a fuse holder at 30amps, it's really only good for 15amps constant, and 30amp for sporadic periods.

 

Considering you were getting a heat build up shows it had a bit of voltage drop across it, likely from a slightly bad join. If it was in the engine bay, it gets even harder for the holder to dissipate it's heat. I've seen a lot of those holders like you're using not rated for use in an engine bay

 

Hopefully the new fix sorts it all out!

 

A thought on their spec for a "suitable size wire" that is hard for the pump manufacturer to spec. It depends on cable length.

For upto about 30 amps constant, on a 5m run, you really should look at about an 8gauge cable. This is pretty beefy thickness cable! But that's what you'd want amps topping out at really on a continuous draw on 5 metres.

The same diameter cable you could run 100amp through continuous if it's only short, like max of a metre.

All cables have resistance, and their total resistance is based on the length of the cable. Then when current flows through said resistance (cable) you have a voltage drop. If there is a voltage drop with current flowing, it means power is being consumed, which dissipates to heat.

 

A battery in the boot right beside the fuel pump, you can use a much smaller cable, like the size of the cable on your fuse holder. Annoyingly, battery run from front of car to rear, needs to be much thicker for the same current.

This is where running an even heavier gauge cable to the rear, and having power distributed at the rear to all things back there, and using negative switching can be beneficial too!

electrical and electronics is fun... Ha ha ha

[GTSBoy]

This also tells a story about heat sinking. The melted 30A one is just free floating plastic - doesn't lose much heat. The big Bluesea one can be mounted to a steel surface and sink heat out that way, in addition to its likely beefier heat shedding abilities.

You can get a long way with thinking about these things in the same way you would for a CPU or other heat sensitive and heat producing electronic jobbie. Adding thermal paste and a place to move the heat to can push the limits on something that would otherwise be inadequate.

But I otherwise agree that the internal contacts inside that melted fuseholder must be shit. Must have been making contact in only small patches.

[robbo_rb180]

Have a look at using midi fuse and thicker quality wire. You generally rate a fuse 50% higher of continuous draw so a 40-45a fuse is what required for the 400+L Walbro/TI pumps. This is why you generally see a lot of race cars with bosch 044 style pumps due to less current draw.
Can also go a 40a/50a bigger relay or switch to a solid state with a finned heat sink.`

[Duncan]

Thanks all...will see how a better quality fuse goes for now an upgrade to a midi it I still have trouble....goes to show that 16a continuous is unusually high for (non factory) auto electronics, the regular off the shelf crap is not made for it.

[Stick180]

On 02/01/2024 at 8:44 AM, Duncan said:

Thanks all...will see how a better quality fuse goes for now an upgrade to a midi it I still have trouble....goes to show that 16a continuous is unusually high for (non factory) auto electronics, the regular off the shelf crap is not made for it.

Im running a 30A midi with my 460 after having the same issues. Running 10ga from the battery to a rear relay then 10ga from relay to pump via bulkheads. Have not had the issue since. The blade fuses cannot dissipate the heat, even with dielectric grease applied.

Midi holder and fuses easily available from Cooldrive. In most cases, the amp rating on consumer based auto electrical components is peak draw, not continuous.

[Duncan]

So the good news is the new fuse holder has been fine for 2 months of summer, absolutely no fuel issues.

Until, 30klm from home Sunday night, the engine stopped on the highway and would not restart. Fuse and holder were good but with limited tools there was not much I could do on the side of the freeway.

Anyway....some time later (about 1am)....the NRMA dropped the car back home, and I had a look at it Saturday.

Turns out the Fuel pump relay had died. It was a sneaky failure, the relay still gave a good click when 12v was applied across the coil, but it didn't actually connect the main contactors. I did have a spare in the shed, swapped it out and all good.

If it fails again I'll swap it out for a solid state on, for now I'm just adding a relay to the onboard spares collection

[Duncan]

So, I figured since weed season is over for 6 months and the stagea was in the shed, I might as well take on the issue with the sender.

Annoyingly the Frenchy's Performance Garage fuel hat and baffles (version 2, not current) deletes the low fuel warning light, and although it comes with a new sender, this is what it shows for a full to the brim tank:

And this is what it shows when the pump starts surging in corners (to be fair, this is an issue with the baffling not the pump mount or sender level)

[Duncan]

So, I disconnected and extended the fuel return, and then jumped the relay to pump it out.

The pump mounting is excellent when not moving on level ground, it pulled all but 2l out of the tank (the 32 GTR factory pump states it is empty with 13l remaining in the tank.

I checked the sender, and very similar to factory it runs from 6ohms full to 82ohm empty, so that was not the issue, however the float hit the bottom of the tank before it hit the stop on the sender, and it hit the upper stop on the sender before it reached the roof so some "adjustment" was in order,

Using the un-patented "angle o matic" I figured mounting at 75o instead of 90o should give the range I wanted (ie, showing empty at about 1/4 tank when surging starts, and showing full then the float is on the roof of the tank.

So, I modified the mount to hold the sender at that angle and put it back in the tank

[Duncan]

So, testing after the adjustment, it seems to be about what I was after.

With an empty tank it showed 81ohms and dead empty on the gauge.

Add 20l and it was off the bottom of the gauge but still on E (76ohm), which is pretty similar to factory which sows E for 13l (and should also stop the surging until E....will check and see)

I didn't get a resistance at 40l because the float was fouling on the fuel pump wires, had to pull it all out again and route it better

At 60l it shows about 2/3 full (23ohms)

I'll check it again when it is full at a servo, (76l per manual) but looks like pretty much what I was after.

[Stick180]

@Duncan Photo links no worky!

[Duncan]

4 minutes ago, Stick180 said:

@Duncan Photo links no worky!

In the last couple of posts? They come up for me, not sure if anyone else has an issue?

Or, is it earlier posts, we seem to have clocked up 10 pages on this ramble

[Stick180]

11 minutes ago, Duncan said:

In the last couple of posts? They come up for me, not sure if anyone else has an issue?

Or, is it earlier posts, we seem to have clocked up 10 pages on this ramble

Just the last few update posts, for me at least

[admS15]

Same, last few posts pics are borked

[Duncan]

Those pics should be working now, something something SSL certificate renewal something

[admS15]

 

[Duncan]

So, 2 months later, I just couldn't see any way to be happy with that tank setup. Basically the baffle area is too big and too leaky, the sender was miles off and the no low fuel light thing really bugs me. Other than the fact the fuel hat could safely supply enough power to the pump, it was worse than factory. Biggest thing that bugged me is it would still run out of fuel in medium-high g corners from about 1/4 tank down which is annoying when you are trying to have a zoom, not to mention potentially engine killing if it gets just the right amount of lean-ness....and we've got a few of those corners in our round trip to town (well, bunnings...)

So, credit to Frenchy's, they have put together a much better designed setup with what is effectively an in tank surge setup.

 

As it happens the actual hat is the same, so I switched the fittings across, re-used the single 525 pump, and added a spare pierburg lift pump that I had (must remember to replace that stock, it was a spare for the race car). The only real work to get it all done was to add a second power and earth to the hat which I did by going from a single output to double output relay (very low draw on the lift pump) and also the sender unit that clips into the factory pump holder was again way too loose (so I re-used the 2mm shims from the previous setup). Finally, I added the low fuel light sender from the factory cradle.

So....I'll report back how it handles low fuel, and if the sender has any relation to actual fuel level in the tank....

[Duncan]

So, funny story.

Kel and the kids and I were in the Stagea yesterday coming home from town, with the car trailer on the back coming home from a rego check, heading down the second last hill to our place.....when the engine stopped running. We managed to roll halfway up the last hill home but that left it stuck on the side of a reasonably steep uphill on a narrow dirt road.

Cranks fine, doesn't fire. I assumed fuel (see last 100 odd posts). Walked home to get the Patrol and a tow rope.

Note - low range 4wd and mud tyres don't produce much traction when there is no weight in the back of a ute. We managed to flat tow the Stagea with the trailer on the back over the last hill and home but it was a pretty long 4wd burnout on the way.

Old cars.

[Duncan]

As I said, I assumed fuel problems, but when I checked the relay it had good +, good -, was clicking with key on and had 12v on both the outputs. So I put the mechanical fuel pressure gauge on it (need to get an electric one to the ECU when I get a free day....) and the pressure was good, so probably not a fuel issue.

Looking a bit further, I noticed Real Dash was showing 9.5v from the ECU, not 11.5+. Put the laptop on the ECU and sure enough only 9.5v at the ECU. Good 11.5+ at the battery terminals and between the chassis and bat + (yes, the battery is getting a charge, she doesn't get used much). Nice to have a different problem every now and then.

Following that a bit further, Link say they need 14v at pin 72, but when I back probe that only 9.5v. Pin 72 comes from the ECCS relay so I checked and there is 11.5v at the battery supply pin (and the relay + pin, it is earth triggered by ECU).  Swapped the relay, still 9.5v at the ECU.

So, I guess Matt is on to this already, but next I'll check continuity between pin 72 and the relay output + pin (or maybe just run a bypass wire as a test) and also see how the ECU earth is ....stay tuned for more....sometime