Fueling issue - Maxed out injectors on Stock Sy

[Sparkz#0535]

Im having some fueling issues and I would be grateful for some feedback. The truck is all stock besides fuel pump ( 255 walbro ) and built lower end. Factory heads, cam , turbo , IC , Exhaust , prom and injectors.

Fuel pressure is 48psi with no vac line and 38psi with the vac line hooked up, I checked it with two different fuel pressure gauges and got the same readings. Looks to be a stock style regulator but it looks really new.

The main issue is the injectors are maxing out. Tuner pro is showing the injector duty cycle going up to 125% at 4k rpms @ 14psi boost in 3rd gear

Truck pulls well on the gate @ 8psi , with the boost solenoid hooked up the truck pulls well until 10psi and then lays over

The factory O2 sensor reports 950mv all the way across the rev range at WOT, boost @ 14psi while the injector dudty cycle climbs to the moon . No knock is shown in the logs, however I did see 1-2deg of knock on one of the shifts

possible issues that I can think of ...
FPR ...Perhaps its not the correct reguator for the application ?
Bad Fuel Pump
Bad injectors
Fuel filter... but its a new wix filter


any ideas of things to check or tests I can run?

 

[Sy2622]

What is your fuel pressure at boost?
Fuel pressure should increase at a 1 to 1 ratio under boost.

 

[syclone3]

Was just working on one of my Syclones that is completely stock. 75k miles Older lady original owner. Engine and turbo was just rebuilt before I bought it. Same mechanic worked on it for decades thought he saw metal in the oil. Its a nice clean example that you dont see today. I did install a Racetronix 255 pump and their relay kit. Just for consistently and safety. Also installed an Accufab Buick/GMC fuel pressure regulator and set the pressure at 50. All stock the truck had some lean spots logging with datamaster. Installed the regulator first which helped with cold start stalling and light throttle accel. I did dyno the truck with the fuel changes on my dyno. Not uncommon to see 100% plus duty cycle over 4000 rpms. Did change the injectors with another set of stockers I had cleaned on my injection machine. Before running on the dyno. Checked the originals later and a few indeed didnt have the best of spray patterns and on a ten sec test. They were down on total CC's. You can see where problems come from on any injected vehicle.

 

[Sparkz#0535]

What is your fuel pressure at boost?
Fuel pressure should increase at a 1 to 1 ratio under boost.

I will check if the FPR is stepping up the presure 1:1. Good idea !

The weather here is nasty right now so it most likely will be a few days before I can get the truck out for testing.

 

[Mikeysy15]

I know times are tough , but when I first purchased my syclone I couldn’t get it to run right . I purchased a turbotweak injector and chip package and installed it and all my problems went away. Truck ran like a beast after that . The 60lb injectors will calibrated chip is a good start. If I were you I wound just go straight to 80lb so you can run e85. Trust me . I did it twice so I know. Get the 80lb injectors and the turbotweak chip set for e85 and for an extra 50 bucks you flip the switch for pump fuel. I’ve been running this for the past year and a half and have never looked back . You won’t max those Injectors out unless your over 27lbs of boost with a big turbo .

 

[corsair231]

If I were you I wound just go straight to 80lb so you can run e85. Trust me . I did it twice so I know. Get the 80lb injectors and the turbotweak chip set for e85 and for an extra 50 bucks you flip the switch for pump fuel. I’ve been running this for the past year and a half and have never looked back . You won’t max those Injectors out unless your over 27lbs of boost with a big turbo .

Will a 255 flow enough fuel to keep up with maxed out 80lb injectors? Might need at least a 340 for that rate, for a little cushion at top anyway.

 

[Mikeysy15]

Yes at least a 340, I run a 450. But remember your not gonna run that much boost so you’ll be fine . You’ll love how much cooler it runs and the extra torque of e85.

 

[Mikeysy15]

Stock turbo is only good till 18psi anyway .
Even my old turbonetics lost efficiency at 20psi.

 

[Sparkz#0535]

I know times are tough , but when I first purchased my syclone I couldn’t get it to run right . I purchased a turbotweak injector and chip package and installed it and all my problems went away. Truck ran like a beast after that . The 60lb injectors will calibrated chip is a good start. If I were you I wound just go straight to 80lb so you can run e85. Trust me . I did it twice so I know. Get the 80lb injectors and the turbotweak chip set for e85 and for an extra 50 bucks you flip the switch for pump fuel. I’ve been running this for the past year and a half and have never looked back . You won’t max those Injectors out unless your over 27lbs of boost with a big turbo .

I wouldnt mind doing the TT chip and 60lb injectors if I need to. I think the 80lbers and e85 are overkill for me and I want to stay on pump fuel. Im not really looking for power just a truck that runs well.

Do you run your 80s on pump fuel or e85 all of the time?

 

[Sparkz#0535]

Fuel pressure with engine running - 38psi vac line on, 48psi vac line off .. fuel pressure steps up 1:1 with boost

key on engine off , fuel pump primes and the pressure jumps to 43psi ... pump turns off and the fuel pressure bleeds down to 15psi in about 4-5 seconds

Something is leaking internally, could be injectors, FPR or pump. Engine oil does not smell of fuel.

More diag to do.

 

[Sy2622]

With vac line off fuel pressure should be 35-38.

 

[Sparkz#0535]

With vac line off fuel pressure should be 35-38.

sorry I had that backwards

 

[Sy2622]

4 possibilities
Fuel pump check valve
Coupling or hose leaking
Injector leaking
Fuel pressure regulator leaking.

There's a test procedure on how to identify the failed component.
Nuts and bolts is
block off one side of the three parts of the fuel loop.
PM sent.

 

[Sparkz#0535]

Did the diag a few weeks back. The issue is in the tank. Fuel pump check valve or leaking coupler or hose. I wont have time to work on it for a few weeks so when I do get the tank out and figure out what the issue was I will report back.

Thanks for the help Sy2623!

Whats a good pump to run that can use the factory wiring ?

 

[Mikeysy15]

I would run the 450 Walbro or even the 525 walbro Hellcat pump with a racetronix Syty Hotwire kit .
All the connections plug right into your stock sending unit . For the pump you still have to do a little splicing and connecting but that’s no big deal

 

[syclone3]

If you arent going for a big build setup. A fresh 255 or an Aero 340 in tank is more than sufficient. I sure see lot Walbro 450 pump failures. Regardless of the fuel. Hellcat pump isnt designed to be used in a return system. Few realize that its a voltage regulated pump in its stock designation. Seen more than half a dozen failures the past year. My fav is watching guys try to control their fuel pressure when that pump is sitting at 13-14 volts all the time. A few get lucky and its in range. Others call and ask why cant I get the pressure below 70 psi.

 

[Mikeysy15]

Wow. No shit. I ran my 450 for a year without a problem . Now I have a 525 but I’ve only had that for 2 months . Thanks for the heads up. More reason for me to finally get a fuel cell and run an external pump