Running out of fuel
#1
TECH Regular
Thread Starter
Running out of fuel
My injector duty cycle is going off the charts and I'm not sure why. What I have should be able to keep up no problem.
6.0 with Borg S480 with Dominator ECU
15 PSI
Fuel system is
Vic Jr with Holley 120 lbs. injectors
2 in tank Walbro 450 pumps (2nd pump comes on at 3 PSI)
-8 from pumps y'd into -10 that goes to the front
-10 y'd to -8 into the back of each rail
-8 return
Boost referenced Holley 12-848 regulator set at 58 psi base
here is a pic of the regulator/rail setup
According to the datalog the fuel pressure goes up to 72 and holds there, no drops or dips.
At about 5500 RPM the injector duty cycle starts to spike and it can't hold the commanded AFR of 11.3. That part of the fuel table is around 800 lbs/hr.
My injectors at 58 psi base are 139.4. That multiplied by 8 at 80% DC is 892 lbs/hr
Any ideas what's going on??
6.0 with Borg S480 with Dominator ECU
15 PSI
Fuel system is
Vic Jr with Holley 120 lbs. injectors
2 in tank Walbro 450 pumps (2nd pump comes on at 3 PSI)
-8 from pumps y'd into -10 that goes to the front
-10 y'd to -8 into the back of each rail
-8 return
Boost referenced Holley 12-848 regulator set at 58 psi base
here is a pic of the regulator/rail setup
According to the datalog the fuel pressure goes up to 72 and holds there, no drops or dips.
At about 5500 RPM the injector duty cycle starts to spike and it can't hold the commanded AFR of 11.3. That part of the fuel table is around 800 lbs/hr.
My injectors at 58 psi base are 139.4. That multiplied by 8 at 80% DC is 892 lbs/hr
Any ideas what's going on??
Last edited by squarles67; 10-17-2017 at 07:52 PM.
#4
TECH Regular
Thread Starter
Fuel is 93 Octane pump.
Voltage is steady at 13.2. I actually replaced the alternator just to be sure, the one I had was the junkyard one that came with the motor.
Voltage is steady at 13.2. I actually replaced the alternator just to be sure, the one I had was the junkyard one that came with the motor.
#6
TECH Regular
Thread Starter
It does run ok and pull hard. It can maintain around 12.6 AFR but I'm not running it all the way out until I figure out the issue. I know the 11.3 commanded is probably too rich but I need to figure out what the issue is before I try and turn up the boost and/or really start leaning on it.
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#10
TECH Regular
Thread Starter
It's a new build that's been running about 6 months now and the injectors were new when I put them in.
The only filters I have are the socks on the pump pickup. I wonder if there's trash in the injectors....hmmm...something to definitely check. That would also make sense with no pressure drop.
The only filters I have are the socks on the pump pickup. I wonder if there's trash in the injectors....hmmm...something to definitely check. That would also make sense with no pressure drop.
#12
TECH Regular
Thread Starter
Something else to check when I get home, thanks. I do have it set to add fuel if IAT gets elevated but I don't believe it is getting too high. Seems like it's around 100 degrees but I need to re-check. I'm spraying 50/50 water meth to keep it in check.
#13
TECH Regular
Thread Starter
I made another pass just now to check the fuel tank vent. I ran without the gas cap to make sure there was plenty of vent. Really didn't make much difference so that eliminates the vent. Fuel pressure stays steady. It was cooler today so air temp stayed around 80.
Looked at air temp from the other day and it was around 100 so no fuel was added there.
I'm going to pull the injectors and check for trash
Looked at air temp from the other day and it was around 100 so no fuel was added there.
I'm going to pull the injectors and check for trash
#17
TECH Fanatic
iTrader: (1)
The higher the rpm the less time the injector has to injector fuel into the cylinder. I was just wondering if your duty cycle was correct. To find duty cycle.
Take 60(seconds) and divide by 5500(your RPM)=.0109(amount of time for 1 rpm)
Multiple .0109 X2 because it takes 2 rotations of crank rotation for 1 complete 4 cycle.
60/5500=.0109x2=.0218 seconds or 21.8 milliseconds.
So your computer is atleast thinking it is holding your injectors wide open.
Now you have to find out if it actually is or more likely your injectors are clogged/faulty.
I am going to try and find the info about the bad batch of injectors for you.
Take 60(seconds) and divide by 5500(your RPM)=.0109(amount of time for 1 rpm)
Multiple .0109 X2 because it takes 2 rotations of crank rotation for 1 complete 4 cycle.
60/5500=.0109x2=.0218 seconds or 21.8 milliseconds.
So your computer is atleast thinking it is holding your injectors wide open.
Now you have to find out if it actually is or more likely your injectors are clogged/faulty.
I am going to try and find the info about the bad batch of injectors for you.