100% duty cly.o2 corr. 25% WHY ???

[1madgumby]

just got back from the track. ran 12.22 @ 111 1.7 60' or half track it is running out of fuel & I dont know why. as is says above. 100% duty cly o2 corr is 25% I have A 255 Warlo pump racetronix harness 75lb injectors & there running out of fuel. New fuel filter. What could cause it to run out of fuel like it does? I know of trucks going in the 10's with just the 255 pump with no harness. IM open to Suggestions

 

[dgoodhue]

Re: 100% duty cly.o2 corr. 25% WHY ???

Bad fuel pump? Do you have a fuel pressure guage, if you do you can verify that the FP rises as the boost rises.

For instance if you are running 40psi base FP (disconnected), At 15 psi you should see 55psi of fuel pressure.

 

[1madgumby]

Re: 100% duty cly.o2 corr. 25% WHY ???

Thats what all the pros say also. Brand new pump, Racetronix harness. fuel filter.

Bad fuel pump? Do you have a fuel pressure guage, if you do you can verify that the FP rises as the boost rises.

For instance if you are running 40psi base FP (disconnected), At 15 psi you should see 55psi of fuel pressure.

 

[BoostedSUV]

Re: 100% duty cly.o2 corr. 25% WHY ???

X2 on fuel pressure. There is no way you should be running out fuel or running even close to 100%DC with a Walbro and 75lbers unless your pump is not putting out the pressure. Maybe the fuel reg is bad and is not increasing FP with boost? You need to verify that for sure

 

[BoostedSUV]

Re: 100% duty cly.o2 corr. 25% WHY ???

Fuel volume could also be an issue if you kinked a feed or return line.

 

[turbodig]

Re: 100% duty cly.o2 corr. 25% WHY ???

John posted a while back that the FAST had a bug when it came to duty cycle (being represented wrong).
Is that what you're running int?

 

[hrodgmc]

Re: 100% duty cly.o2 corr. 25% WHY ???

Is meaney still doing their work or just BS3 only?

 

[1madgumby]

Re: 100% duty cly.o2 corr. 25% WHY ???

BS3 only

Is meaney still doing their work or just BS3 only?

 

[1madgumby]

Re: 100% duty cly.o2 corr. 25% WHY ???

Old style speedpro

John posted a while back that the FAST had a bug when it came to duty cycle (being represented wrong).
Is that what you're running int?

 

[1madgumby]

Re: 100% duty cly.o2 corr. 25% WHY ???

Going to mess with is some this weekend. thats what I thought also, I could not see how it is runn out of fuel..

X2 on fuel pressure. There is no way you should be running out fuel or running even close to 100%DC with a Walbro and 75lbers unless your pump is not putting out the pressure. Maybe the fuel reg is bad and is not increasing FP with boost? You need to verify that for sure

 

[1madgumby]

Re: 100% duty cly.o2 corr. 25% WHY ???

I looked did not see anything kinked.

Fuel volume could also be an issue if you kinked a feed or return line.

 

[Windedv6]

Re: 100% duty cly.o2 corr. 25% WHY ???

John posted a while back that the FAST had a bug when it came to duty cycle (being represented wrong).
Is that what you're running int?

Is is with the FXI only. The classic (or speed pro model is fine). I had to run a double pumper (later an A1000) pump to get enough fuel. I don't think a single 225 is going to handle your setup at full boost.

A couple of things to check:

Make sure you are getting an extra lb of fuel for each lb of boost.
Make sure that you are getting 13+ volts at the pump.
Make sure that your fuel filter is fresh
Make sure you have at leat 1/2 tank of gas

If you are low on fuel delivery then your injector pulse width will open longer as it looks for more fuel, which can show a higher duty cycle. You have to make sure you have a constant fuel pressure load to the rails. I run my pumps at 14 volts at all times which puts out a higher flow/pressure.

You can also raise your fuel pressure to 45 - 50 lbs as your starting point to get more out of your injectors (if the pump can handle it), If you raise the starting fuel pressure you will half to retune your tables.

John

 

[1madgumby]

Re: 100% duty cly.o2 corr. 25% WHY ???

Just checked the fuel filter & is all good. no dirt or debrie in it.

 

[1madgumby]

Re: 100% duty cly.o2 corr. 25% WHY ???

ok will look into A (A1000) with the controller, filter is good, 3/4 tank of 110 octane, Will check the voltage tommrow & also the fuel gauge drop this weekend.

thanks.

Is is with the FXI only. The classic (or speed pro model is fine). I had to run a double pumper (later an A1000) pump to get enough fuel. I don't think a single 225 is going to handle your setup at full boost.

A couple of things to check:

Make sure you are getting an extra lb of fuel for each lb of boost.
Make sure that you are getting 13+ volts at the pump.
Make sure that your fuel filter is fresh
Make sure you have at leat 1/2 tank of gas

If you are low on fuel delivery then your injector pulse width will open longer as it looks for more fuel, which can show a higher duty cycle. You have to make sure you have a constant fuel pressure load to the rails. I run my pumps at 14 volts at all times which puts out a higher flow/pressure.

You can also raise your fuel pressure to 45 - 50 lbs as your starting point to get more out of your injectors (if the pump can handle it), If you raise the starting fuel pressure you will half to retune your tables.

John

 

[BoostedSUV]

Re: 100% duty cly.o2 corr. 25% WHY ???

I don't see why you would need an A1000 pump or a double pumper? The truck will only use the amount of fuel it needs no matter what Engine management is controlling it. With 75# injectors and a 255 walbro you should not be maxing out the injectors IMO.

 

[1madgumby]

Re: 100% duty cly.o2 corr. 25% WHY ???

Will know more after this weekend.

I don't see why you would need an A1000 pump or a double pumper? The truck will only use the amount of fuel it needs no matter what Engine management is controlling it. With 75# injectors and a 255 walbro you should not be maxing out the injectors IMO.

 

[turboj91]

Re: 100% duty cly.o2 corr. 25% WHY ???

AJ, break open your fuel line and jump your pump relay and let it run into a 5 or 6 gallon can. 255 gph should run 4.25 gal in one minute with no load. see if the pump is at spec and then go from there.

 

[1madgumby]

Re: 100% duty cly.o2 corr. 25% WHY ???

ok, will try it today.

Thanks.

 

[1madgumby]

Re: 100% duty cly.o2 corr. 25% WHY ???

All lines good. not kinked checked from front to rear

Fuel volume could also be an issue if you kinked a feed or return line.

 

[1madgumby]

Re: 100% duty cly.o2 corr. 25% WHY ???

Did it off the fuel rail with A -4 n2o line got 3/4 gal. in 1 min.

AJ, break open your fuel line and jump your pump relay and let it run into a 5 or 6 gallon can. 255 gph should run 4.25 gal in one minute with no load. see if the pump is at spec and then go from there.