520R SV build has commenced

[Rosteri]

John, my transfer pump turned off at the dyno (my fault), so the pressure pump struggled to keep up pressure (low fuel level in swirl pot) and it caused loads of sensor faults and ecu warnings due to missifire, which we unfortunately started troubleshooting before we noticed the fuel pressure. Pressure pumps are really bad in sucking, so I’d try without that collector mat first.

[JohnCh]

Thanks @Rosteri , I'll keep that in mind and add it to the troubleshooting list.  However, this pump is designed to work in tank and pulling from a filter, although much smaller and a different design than the Hydramat.  Also, it happened a few times at idle, when demand on the pump was very, very low.  A big concern is Deatschwerks giving the pump the all clear, then after reinstalling it, the issue goes away or is very, very sporadic making it even harder to troubleshoot.  

[Anaximander]

John, If all else fails, I installed a Holley in-tank fuel pump with no return line and feeding through a hydramat. Summit is very proud of their return line in-tank fuel pump but they get rave reviews on reliability. 

Holley In-Tank Retrofit Fuel Pump Modules 12-130

Fuel Pump, Electric, In-Tank, Retrofit Module, 60 psi, 255 lph, Gasoline, Return Style, Each

Part Number: HLY-12-130

They want $800 for this gem but if it solves your problem, just 4 hours of phone consultation with the Brits would pay for the pump

[JohnCh]

Thanks @Anaximander but I have already fabricated the module as shown below and have the Hydramat, so the only difference is the pump, which seems to be one of their standard in-tank pumps.  

 

 

Thanks,

John

 

[Rosteri]

John, the high pressure pump works at full speed all the time in connection with the fuel regulator, so engine idle/full speed shouldn’t make a difference if it stalls or not. But anyway, it is an easy check when you get the pump back. 

[JohnCh]

Oops.  Fair point.  I'll call Holley and ask if there are any undocumented recommendations regarding fuel pump compatibility.  I suppose another remote possibility is the hose between the Hydramat and pump is collapsing.  I'll examine that closely when I reinstall the pump.  I still wonder about the weird TPS spikes as the engine stalled.  

[Rosteri]

I agree, those TPS spikes are weird. But again, I troubleshooted 3 hours at a dyno $$ rate my camshaft trigger failure, which was just a result of the engine missfiring due to no fuel… 😉

[JohnCh]

I did confirm there was fuel in the tank when I removed the fuel pump   

 

-John

[sf4018]

Just a thought in a different direction - the hydramat: does it work with higher fuel flow return to tank applications with it being basically a big filter bag? Can the pump take the negative pressure intake?

[JohnCh]

It's designed to work with either return or returnless and with much higher flowing pumps than I'm running.  For return style, they want the hose pointed about 1" above the collection point.  I believe that's how I installed it, but given it's somewhat blind, it could be off by a bit.  I'll ask them about that as well.

 

Thanks,

John

[Anaximander]

John and gang, There is an interesting 2015 article on the features of a Holley HydraMat system and many of the nuances of what is being attempted with the reported 9 different HydraMat configurations to prevent vapor lock issues. An interesting read: https://www.motortrend.com/how-to/1508-holleys-new-hydramat-fuel-pick-up-system/

[JohnCh]

Thanks @Anaximander, the stalling began after driving 2 miles in a neighborhood with air temps around 58F.  I'm not sure if that combination is sufficient to create pump or fuel overheating issues, but I'll ask Holley for more info on this when I speak with them.

[JohnCh]

I just had an interesting conversation with Holley.  There are a few potential issues with the installation that could create either too high a load for the pump ( @Rosteri's theory) or over aeration of the fuel from the return line ( @sf4018's line of thought).  Looking at the photos of the assembly out of the car, and remembering the fuel level when I removed it, made me realize that the return may have been hitting the floor and aerating the fuel.  If excessive, this could cause issues for the Hydramat.  More likely though is the two 90 degree fittings and 12" of hose between the Hydramat and pump creating too big a load for the pump to overcome.  Another possibility is that hose rides up the slop of the tank floor, creating a high spot in the routing that traps an air bubble. 

 

While I wait for the pump to be returned, I'll print a new fuel assembly lid with inspection ports to let me see how everything sits in the tank, then figure out a game plan.  It most likely involves a new Hydramat with an offset collector that can be placed closer to the pump, and possibly changing the angle of the pump mount to allow a straighter shot to the Hydramat fitting.  Thanks for the insights and stay tuned.

 

-John

[Anaximander]

John, Your build thread and in particular, this most recent challenge has had me thinking about all of the complex variables that go into building a car. I thought that the challenges I had with the FiTech FI system were challenging until I read your recent trouble shooting woes. I had read about 50/50 acceptance of the FiTech self-learning ECU and some of its gremlins that some people have hated and some have loved. It really emphasizes the point that building race-bred cars is not necessarily for the faint of heart. It certainly taught me a level of patience throughout my build that I barely had enough to spare. There were times when I felt like throwing up my hands or just plain throwing up thinking that I was hitting barriers that were thwarting the successful outcome of a build. However, as I seem to maybe have come to the end of most of the challenges, the feeling of accomplishment is worth the tough journey IMHO.

 

Glad that Holley had some seemingly good insights for your potential problems. We are all expecting to be seeing a blur pass by in the form of a Caterham 520R in the near future!

 

Edited July 5, 2023 by Anaximander

[JohnCh]

When you aren't following a well-traveled path, issues are expected, and in a twisted way, part of the fun.  Quite frankly, I'm really surprised this is the first real problem I've encountered, but if indeed it is a confluence of design elements in the fuel assembly, it should be a relatively straightforward fix.  I've already redesigned the assembly lid to retain both the fuel pump bracket and return hose fitting while adding a massive inspection port which should take the guess work out of the equation.  I'll print that later today.

 

And if you think this is challenging, imagine how hard it must be to ensure all the correct parts are included in an expensive kit.  Caterham has been doing this for 50 years, yet they still can't figure out how to do it -- it must be monumentally hard <sarcasm mode off>   

[JohnCh]

I heard back from Deatschwerks.  The pump passed the warranty test, but during the endurance test there was "a slight hiccup in amperage most likely from brush break in."  They feel it's within spec but opted to replace it in good faith.  I also purchased injectors from them and made a few pre-sales technically enquiries during that process.  Every experience with them has been very, very positive.  Even opening the support ticket online resulted in a response within 30 minutes.  Deatschwerks is based in OK and worth keeping in mind for fuel system products:  https://deatschwerks.com/

 

I'll test the new pump before making other changes.  However, once the issue reappears or I am confident that was the source, I'll update the in-tank plumbing to minimize resistance.

 

-John

[MV8]

I was just looking at your intank system. To reduce the aeration, I would replace the elbows with full flow fittings, raise the pump by shortening the pump outet hose if needed for the gradual bends of the full flow fittings, and either shorten the horizontal hose or use aluminum tube between the ends with two more clamps on 1-1/2 inch long pieces of hose as couplers to ensure the hose does not collapse. Be sure to use hose rated for intank use.

[JohnCh]

Thanks, but I'm thinking about a different direction.  With the internal fittings, there is only room to raise the pump about 1/2" and still accommodate the bend in the output hose which is required for fitment -- space is really tight.  Current thinking is to replace the Hydramat with a slightly larger version that positions the collector at the end rather than in the middle and attempt to position the pump end so there is a short, nearly straight shot to the Hydramat, thus eliminating both 90 deg fittings.  I need the pump back to play with this and ensure I can make it work.  The hoses are rated for in-tank placement.

 

One thing Deatshwerks brought up is wiring.  The pump (255 LPH) runs at a little less than 10 amps.  I believe, but need to verify, the fuel pump wire is 16 gauge, which technically is fine for that amperage.  Deatschwerks, however, likes to use 12 gauge wire.  Running new wire is doable, but a pain.  Any thoughts there?  Is anyone running a larger pump with stock Caterham wiring?

 

Thanks,

John

[Rosteri]

As you pointed out 16 awg is just fine for 10 amps and 255 LPH is still a relatively modest pump, so at least I wouldn’t stress about it. 

[Anaximander]

John,

I had a wire burn out on a heavy duty turbo fan I run on Stalkers and it was 16 awg. I was advised to used 12 awg but opted for a ridiculous 10 awg on a separate switch so I would never have to worry about transient spikes. I did a Google search on 12 awg and 10 amps and this is the response I got:

"While a 16 gauge wire can technically handle about 10 amps at 12 volts, it is still advised to not go over 8 amps. This is due to the reason that over a longer distance, your 16 gauge wire may have a non-uniform construction.Feb 23, 2023"

I personally do not like having things that are critical to performance and running constantly to be "underwired". Given what I found here and the concerns I have for certain critical components such as a fuel pump and in my case, a relatively small radiator cooling an LS3/480 that I owned, my personal choice would be to run 12 gauge wire and not have to ever worry about the potential lack of uniformity in the existing thinner strands of wire. I suspect that the run of your 16 gauge from the fuel tank to the main bus is likely the longest run of wire you have other than the tail lights which don't have that kind of amp draw.

Edited July 5, 2023 by Anaximander