I'm unsure if this is the appropriate section, but as I'm running an Elite 2500 on my setup, I figured I'd start here.

I am working through building out my tune for wastegate pressure at the moment. In previous pulls, 4th gear, 2000-3500, from vacuum to 98kPa, 100% throttle, I had no issues. This time, I decided to put my foot down in a lower gear and take the revs up higher.

So I start here. ~3600rpm, 12% throttle. Fuel pressure looking good. Everything is in line as I'm cruising around.


I get to 3700rpm, building boost, and the secondaries begin to come online. Fuel pressure still looks fine, if tracking marginally behind boost.



I run into problems at 4200rpm. 93kPa, 50% throttle, and my fuel pressure is now well below boost. My Fuel Pressure Differential DTC has flagged as I've now dropped below the 285kPa threshold for long enough. The Secondaries are still just barely beginning to come up. The engine protection kicks on a moment later and ignition is cut, exactly as implemented.




Running Walbro 450 with ID1050/2000 injectors and Turbosmart FPR1200 with an ID750 fuel filter. My fuel system ought to be up to the task of at least this much.
My main question is, as the secondary injectors come online, is a pressure drop like this expected if I request a whole lot of fuel quickly? The entire event takes place over less than a second and a half. The fourth gear pull with no issue happens across a wider period of time with no issue. Or is the single fuel pump not quite enough for this?

The WOT 4th gear pull I mentioned, no issue, as far as I can see. It is tracking a smidge behind, though.




Edit: I'm relatively sure I'm maxxing out the fuel pump... If anyone can tell me otherwise, please. Make me not have to buy another pump lol

on the WOT page, 386kPa, ~56psi
Walbro 450 flow rate at 13.5v, should be ~393l/hr, ~6550cc/min if my math is right.
At the top of the pull, the flow rate for the injectors is 981/2079, times 2, 6120cc/min

There's no headroom. Do I have my secondaries coming on far too early? At the top of that pull, primary and secondary are only ~25% duty cycle.

 

If you aren't going over 85% DC or anywhere near it you are better off running lower base pressure, the pump/regulator will behave more linearly. Andy Wyatt actually had a chart on his old Adaptronic page where he had built a test rig and mapped linearity/sag behaviour for a bunch of regulators, the turbosmart were the best of the group. You may still be able to find it hosted somewhere.

Also are you running a surge tank or keeping the tank over half full? The FD does get fuel starvation, which is more likely to show in lower gears pulling higher Gs.

 

A lower base fuel pressure than 43.5psi/300kPa? That is the typical, iirc, so was the starting point.

I'm thinking I ought to do away with the fuel flow percentage table for the secondaries right now. Rely more heavily on the primaries. I will give it a shot later this week, I guess.

Not running a surge tank at the moment, but was more than half a tank full. So it shouldnt have been an issue I wouldnt think.

 

What size lines, how is your pump wired, are your fuel lines series or parallel? 1000/2200 or thereabout is our standard injector size for our builds using an aem 340 on the stock lines. We have not run into an issue as you have described. I would like to think your issue is outside of the tune.

 

Lines from tank to engine are OEM, to the rails are -6AN iirc
Pump is hardwired from battery with its own relay.
On the rails, they are plumbed in parallel. Each rail getting its own feed at the back of the block, at the front feeding into either side of the FPR and the return out the bottom. The base is the CJ Motorsports kit.

On looking back at the duty cycles at the time of the engine protection kicking on, they were only 56% and 17%. This I believe comes in at less that 1000cc/min per rotor. So, I should still have a lot of overhead here. I was looking at the full flow rate before rather than what was being requested at the time. On the last image for the 4th gear WOT pull, it was requesting only ~1500cc/min for everything (1042/2196 total flow, 25.9%/22.2% duty cycles, 269.8cc/min / 487.5cc/min). Please check me if my interpretation/math is wrong.

I will go ahead and release the remaining trust in my builder and verify the installation of the relay kit and the fuel pump myself prior to the next logging session.

 

I'm no tuner so your math is way over my head lol I don't know how to interpret data to that degree but I don't have to since that's a job for my tuner 😅. I only bring up an outside issue since I assume the tune is set up properly. Your fueling configuration is as correct as it can possibly be. I would suggest monitoring fuel pump voltage with a multimeter while doing a pull if you can do that safely.

It would be very convenient if it is simply a setting in the ecu casuing your woes

 

Found this when examining the fuel pump. Bit strange. Unsure if it's an installation error or manufacturing defect.



My friend sent me a picture of his when he swapped his pump and it had the same issue. I doubt this is the culprit. But, I'll try to fix it best I can.
The fuel pump itself does appear to be what it should be, which is great.




A little grease and the seal is back in. Maybe I'll get lucky?

 

That connector at the hanger is going to fail. You need to get ahead of that and run the wires appropriately for what you have. The worm clamps are also going to fail especially on that type of hose. You need to be using fuel injection clamps. They are completely smooth all the way around and done EAT the hose by cutting into it.

 

Its most likely the FD fuel pump bulkhead connector.
Seen this so many times.....the stock FD bulkhead fuel pump connector doesn't like being wiring to larger pumps that draw more amps.
Bypass it with the proper bulkhead/wiring to feed the larger pump.

Steve

 

Alright guys. Thank you for the input. I talked to one of my friends who was also running into the same sort of issue. His solution was to solder the heck out of the connector for a "solid" connection. FDAUTO, I like your solution better lol. So it looks like I'm going shopping. Reckon I'll update this thread after the installation to see if the problem was fixed. Til then, I'll just cruise.

 

sounds good. Cody Hammond, if youve crossed paths with him, is out there. if you need to order parts, do it through him. you can call him our remote sales rep lol. fast shipping and great prices. hamm_tuned on instagram

 

The seals on the Aptiv connectors aren’t fuel compatible. I am always amazed and disappointed that Walbro continues to use those connectors and seals in their kits. You’re better off removing the connector and using a butt splice and covering it with PTFE heat shrink.

 

If this has been an ongoing issue, I'm very surprised that my builder left it as is. I keep seeing product images for the install kit with a red seal though. Maybe the product has been updated since this was purchase (c.2019)?

I have ordered the bits that FDAUTO has suggested, in addition to some regular rubber fuel line and a few of the fuel hose clamps, just waiting for them to arrive. If it fixes the issue, I will be going into my friends' cars to see if they have the same issues with this setup and then replacing it if they do.

 

Submersible fuel line is what you need for the in tank. 3/8 for that pump i believe. If you use the regular hose then it will swell up and rupture in the tank. I would suggest using a pump with a 5/16 outlet to save you some headache trying to adapt a 3/8 hose to a 5/16 pipe. In the interim you can monitor fuel pressure and sww what you're getting. At least that way you will know if this venture will yield favorable results. It would suck to do all this work and it not change anything

 

Well we have some good news.

Got over that hump successfully and boost as well as fuel pressure are looking solid. Now I can go and work on the top end of the tune.

I did the rewiring with bulkhead connector as suggested by FDAUTO. However, I feel massively ripped off by the "ATL electrical bulkhead connector. I bought 4 for my and each of my friend's cars so we could do them up the same way. It was only after that I find the same thing on McMaster for ~1/7 the price.



I did order the pigtails from Racetronix as well, only for them to not work for this application. I ordered 10awg Tefzel wire to extend the wires that were there, only to find that they were 12awg lol. Oh well. At least my crimps fit over them, but only just. Some Raychem heat shrink and that complete the job for me.





Using basically the same connector as what was in the tank, I tried making it more easily serviceable. The connectors and pins for this gauge wire are beefy.






And the kicker. When putting in this heavier duty wire, I decided to run it straight to my relay, bypassing any additional stock connectors. On the connector from the chassis harness into the fuel pump subharness, I found this:




Needless to say, I'm happy I had my engine protection set up the way that I did, even if it was quite conservative. I would definitely not wanted to just push through this. Speaking of, my Fuel Pressure Differential minimum was set at 285kPa. It is now set at 270kPa, the default. In the above screenshot, it doesnt go below 292kPa, but we will see in the future as I continue to monitor. But for now, I think we can call this one solved. I appreciate the feedback.

 

this is a happy ending. glad you got it sorted out...

i will update the description in the video. while i dont use the ATL pass through anymore due to the crazy high cost. it nice to see that mcmaster has struck again lol. seems like everything is on there for what can be considered wholesale compared to "branded" parts.

 

I need to do this on my FC. I have a hard time trusting the factory Hanger bulkhead connector...

-M

 

Wow, very helpful