LLY FICM

[2004LB7]

Yeah. I'm going to poke around with it a little more before condemning it


It would be interesting to see how many engine hours each one had at the time of failure. I wonder if we can create a thread / poll to see if we can start collecting enough data to see if there is any sort of data that tells us when one should consider replacing the capacitors before they blow. Not sure there are enough people that recorded that information or even had failures to come to a meaningful conclusion but would be great if there was.

 

[PureHybrid]

Hour meter reset on my truck years ago, but it was over 6k. I don't daily it anymore so I'd say maybe 6500

 

[2004LB7]

Makes me wonder if they where using 2 or 3 thousand hour capacitors and thus the issue. They where relying on the temperature rating alone and thinking that the actual temperature would be low enough that it would extend the life. Wonder how much that is holding true

 

[PureHybrid]

Probably a bean counter started a company making capacitors for bosch control modules, got the bid and made out like mad on both ends with a nice salary increase.

Anyone bothered to measure under hood temps on these trucks? I wonder how hot that module actually runs, I can't see relocating it somewhere else being beneficial unless it wasn't under the hood

 

[PureHybrid]

Air temp thread no worky

under hood air temps

Side note from fuel temp thread At night running 70 mph outside air 65. Under hood air temp was steady at 68-69. Got off the highway to pull into a Pilot. By the time I stopped in the parking lot under hood air temp was 95 and still climbing After a few minutes of sitting with the...

www.duramaxdiesels.com

Searching a few places and no real solid measurements, lots of speculation

 

[2004LB7]

Another point about these FICMs. I've heard for years not to run too much lift pump pressure as the FICM can leak. From what I see, there is no way unless you are pushing hundreds of pounds of pressure. The cooling channel is just a straight shot through the middle. In other words, a simple tube with threads on each end. There is nothing to leak unless the pressure is high enough to crack the aluminum. I just can't see it until you reach at least several hundred or more PSI

 

[Chevy1925]

Air temp thread no worky

under hood air temps

Side note from fuel temp thread At night running 70 mph outside air 65. Under hood air temp was steady at 68-69. Got off the highway to pull into a Pilot. By the time I stopped in the parking lot under hood air temp was 95 and still climbing After a few minutes of sitting with the...

www.duramaxdiesels.com

Searching a few places and no real solid measurements, lots of speculation

Fixed for ya

 

[2004LB7]

Air temp thread no worky

under hood air temps

Side note from fuel temp thread At night running 70 mph outside air 65. Under hood air temp was steady at 68-69. Got off the highway to pull into a Pilot. By the time I stopped in the parking lot under hood air temp was 95 and still climbing After a few minutes of sitting with the...

www.duramaxdiesels.com

Searching a few places and no real solid measurements, lots of speculation

I wonder where the measurements where taken from. That might make a big difference. I'd like to see one right where the FICM would be mounted along with maybe by the firewall, batteries, wheel well and radiator shroud

The temps he measured at the highest where only 115°. Would likely get higher if it was 110° out and slow city traffic. Standard capacitors are rated for 105C (221F) and the stock ones are rated for 125C (257F) so there should be quite a bit of headway there. Makes me think relocating the FICM and not running fuel through it can definitely increase the life

 

[juddski88]

Another point about these FICMs. I've heard for years not to run too much lift pump pressure as the FICM can leak. From what I see, there is no way unless you are pushing hundreds of pounds of pressure. The cooling channel is just a straight shot through the middle. In other words, a simple tube with threads on each end. There is nothing to leak unless the pressure is high enough to crack the aluminum. I just can't see it until you reach at least several hundred or more PSI

View attachment 113347

View attachment 113349

I've never seen one leak internally from high pressure, but those cheap banjo sealing washers leak all the time at much past 20psi. I think back in the day not many people took the time to fully investigate their observations, myself included. Also, there wasn't much reason to go over 15psi at idle anyhow because of having to recalibrate the FPR.

 

[PureHybrid]

I wonder where the measurements where taken from. That might make a big difference. I'd like to see one right where the FICM would be mounted along with maybe by the firewall, batteries, wheel well and radiator shroud

The temps he measured at the highest where only 115°. Would likely get higher if it was 110° out and slow city traffic. Standard capacitors are rated for 105C (221F) and the stock ones are rated for 125C (257F) so there should be quite a bit of headway there. Makes me think relocating the FICM and not running fuel through it can definitely increase the life

What body style truck did that guy have? I thought I remembered him having an LMM. The low fuel thing seems interesting, I run mine down to the fuel light all the time

 

[2004LB7]

Some additional capacitors to consider for replacing the 3x 470uf ones.

These are basically a direct replacement for the electrolytic that are in there but are a polymer version instead of the electrolyte. This increases the reliability of them due to not having any electrolyte to spill out. Downside is they don't have the "self healing" properties of the liquid electrolyte ones so they can't tolerate voltage spikes or reverse voltage. Plus side is they are 35 volt rated vs the 14 volt of the original so that may make up for it

https://www.digikey.com/en/products/detail/panasonic-electronic-components/EEH-AZS1V471B/13574561

The next two options are not direct replacements and will require adding leads to the capacitor or bending the leads to fit. Nothing too complicated.

Tantalum - Polymer Capacitors. These are very stable and extremely long life. But... They are expensive and because of the capacitance values you'll have to stack some to get to the right amount. Could be tricky for those not familiar with soldering electronics. You'll probably need 9x of these to get close to the same original combined value of the old ones. These supposedly have no rated lifespan because they do not degrade under normal operating conditions. Can be considered infinite. Downside is their spectacular failure rate. If over voltage passed it's surge rating to the point of failure cause them burst in flames, which would surely damage the PC board beyond repair

https://www.digikey.com/en/products/detail/vishay-polytech/T54EE157M030CSA075/15182353

And lastly is a ceramic capacitor. These may actually be the best replacements as they will be much easier to install with their long leads. They are a different dimension and lead spacing but they should be able to be mounted slightly to the side with the leads bent to reach the through holes for soldering. They are not polarized so can handle reverse voltage equally well as forward. Individually they are the most expensive but you need only three like the original design. So for the price and performance they might be the best way to go. Failure will often be a soft short where the capacitor decreases in resistance between the leads to the point where it would likely just pop the fuse. The board would have a high likelihood of being saved

https://www.digikey.com/en/products/detail/united-chemi-con/KTD250B477M99A0B00/6189622

 

[PureHybrid]

So are you going to start a repair service?

 

[2004LB7]

Haha. No. But I'd replace the capacitors for anyone who wanted me to for a small nominal charge, not including the price of the capacitors or shipping. No guarantees as I have no way of testing them.

Like all other repair services, I'd probably pass on all boards that had any burning. It would be more along the line of upgrading capacitors for those who have a lot of hours on theirs and want a little piece of mind. Notable forum members only of course. No random guys shipping me stuff and claiming I ruined their stuff

 

[PureHybrid]

I completely understand that. Shoot me a price on what you'd charge to go through a good working unit.

Which capacitor would you choose for these? Those ceramic seem interesting but I take it you have to buy a box of 10? I've never bought through that website before

 

[Bdsankey]

Haha. No. But I'd replace the capacitors for anyone who wanted me to for a small nominal charge, not including the price of the capacitors or shipping. No guarantees as I have no way of testing them.

Like all other repair services, I'd probably pass on all boards that had any burning. It would be more along the line of upgrading capacitors for those who have a lot of hours on theirs and want a little piece of mind. Notable forum members only of course. No random guys shipping me stuff and claiming I ruined their stuff

I've got 5 LB7 FICMs here that are in good working order that I wouldn't mind having you poke around in

 

[2004LB7]

I've got 5 LB7 FICMs here that are in good working order that I wouldn't mind having you poke around in

It would be interesting to see if the values of the capacitors are any different. It's my understanding that the injectors on the LB7 are ~96 volts or double the LLY's 48 volt injectors. The low voltage chip driver circuit I would think is the same. I'm going to guess they would use the same capacitors for that. The injector capacitors may be 125 volts at half the capacitance

 

[2004LB7]

I completely understand that. Shoot me a price on what you'd charge to go through a good working unit.

Which capacitor would you choose for these? Those ceramic seem interesting but I take it you have to buy a box of 10? I've never bought through that website before

I think if you are going to be a one off then choosing the cheapest option with the polymer caps or even staying with the electrolytic ones of higher voltage would be the way to go. If there are several people willing to jump in and share the cost of purchasing the ceramics and be guinea pigs for testing then I'd be open to it. We'd need three people for the 10 pack of ceramic capacitors which would bring the cost of capacitors to $150 per person. Then what, maybe a hundred dollars for labor to swap them out and reseal them up. Then shipping at about $20. Probably should have insurance on that, which may be like another $20 for $2k of insurance.

So your looking at about $300 per person if you get three on board with the ceramics.

Tantalum would be about the same cost per person but you can buy those capacitors one at a time or however many you need so you don't have to get other on the list

Aluminum polymer or electrolytic are less then $10 for three of them so that would make it about $150 per person

I'm actually thinking, based on the few photos people posted online of their burned up LLY FICMs is that the main capacitor that fails is the center of the three. I'm wondering if the traces are too close to the injector traces in the internal layers at somehow it arcs or conducts across it and blows the capacitor and board. If this is true I don't think that changing the capacitors out will fix the design problem. It should be random capacitors if they are all the same age but I haven't see any of the side capacitors in the photos show the burning at the bottom

 

[Bdsankey]

I think if you are going to be a one off then choosing the cheapest option with the polymer caps or even staying with the electrolytic ones of higher voltage would be the way to go. If there are several people willing to jump in and share the cost of purchasing the ceramics and be guinea pigs for testing then I'd be open to it. We'd need three people for the 10 pack of ceramic capacitors which would bring the cost of capacitors to $150 per person. Then what, maybe a hundred dollars for labor to swap them out and reseal them up. Then shipping at about $20. Probably should have insurance on that, which may be like another $20 for $2k of insurance.

So your looking at about $300 per person if you get three on board with the ceramics.

Tantalum would be about the same cost per person but you can buy those capacitors one at a time or however many you need so you don't have to get other on the list

Aluminum polymer or electrolytic are less then $10 for three of them so that would make it about $150 per person

I'm actually thinking, based on the few photos people posted online of their burned up LLY FICMs is that the main capacitor that fails is the center of the three. I'm wondering if the traces are too close to the injector traces in the internal layers at somehow it arcs or conducts across it and blows the capacitor and board. If this is true I don't think that changing the capacitors out will fix the design problem. It should be random capacitors if they are all the same age but I haven't see any of the side capacitors in the photos show the burning at the bottom

I'd send in an LB7 if you wanted to take a look at it and see if they can share caps. If so, I have 5-6 I'd send in which may help with costs.

 

[TheBac]

Looks like Jason has found a new side biz.

Digikey is a playground for electrical engineers. My son loves that site.

 

[PureHybrid]

I'm actually thinking, based on the few photos people posted online of their burned up LLY FICMs is that the main capacitor that fails is the center of the three. I'm wondering if the traces are too close to the injector traces in the internal layers at somehow it arcs or conducts across it and blows the capacitor and board. If this is true I don't think that changing the capacitors out will fix the design problem. It should be random capacitors if they are all the same age but I haven't see any of the side capacitors in the photos show the burning at the bottom

I seem to remember a video of a guy peeling his open and it was an outer cap that was burnt, maybe not. But if your theory is correct about the traces, it could still be a crap shoot on which one would get torched first?