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

[1madgumby]

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

it is A 255 liter pump.
checked at the pump & the volts only read 3.8 volts with the key on for the 8-10 sec. prime period.
fuel filter is good checked it out yesterday.
3/4 tank of gas.

Would the pump even run with 3.8 volts? Not 13.8 ( 3.8 )

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

 

[Ty 1885]

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

Had 7 volts on mine. I had to run new wires from ecm to relay to pump. Now its 13.5 volts.

 

[turboj91]

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

Converting LPH to GPH, you should be just over 1.1 gallons in 1 min. The low voltage makes it run slow. Bet when you find the voltage drop and correct it, you problem will be gone.

 

[Beavis]

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

If you have a racetronics harness, is that voltage at the harness or the pump? You might just have a bad ground on the hearness or loose/poor connection with the harness. Bypass the harness and check your voltage through the stock wiring to see where the problem is.....:2cents:

 

[1madgumby]

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

Checked on both sides same volts on both sides 3.8 going to try with it running tomrrow.

If you have a racetronics harness, is that voltage at the harness or the pump? You might just have a bad ground on the hearness or loose/poor connection with the harness. Bypass the harness and check your voltage through the stock wiring to see where the problem is.....:2cents:

 

[1madgumby]

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

sounds like A volt problum to me. 3.8 volts is way low.. When I was at the track, seems like it kept getting worse, but the ET. times stayed constent, except for the last pass it started breaking up worse then it did before so I got out of it.

Had 7 volts on mine. I had to run new wires from ecm to relay to pump. Now its 13.5 volts.

 

[Big Mike]

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

Did you measure the voltage with the truck running if not measure the voltage with truck running? Your meter may be slow acting for those 8-10 seconds when you took your readings. Are you sure your meter had a good ground? Is the meter your using digital or analog? Is your racetronix relay hot wire coming off the back of the alternator? Do you have any way to measure your fuel pressure under WOT so you can see if it is going up with boost?

 

[1madgumby]

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

just checked it with it running, shows 14.6 volts to the pump. battery was down so it might be that much with the Alt. charging the battery. Yes it has A good ground. digital meter. Hot wire stright to the battery in the back. getting A line made tomrrow to do the WOT fuel test this weekend.

Did you measure the voltage with the truck running if not measure the voltage with truck running? Your meter may be slow acting for those 8-10 seconds when you took your readings. Are you sure your meter had a good ground? Is the meter your using digital or analog? Is your racetronix relay hot wire coming off the back of the alternator? Do you have any way to measure your fuel pressure under WOT so you can see if it is going up with boost?

 

[JSM]

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

I would suspect fuel flow with no pressure (line unhooked test method) -vs- one under pressure would be 2 different animals. not sure your loose line tests are valid IMO.

 

[1madgumby]

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

going to try to do the WOT test sometime this weekend to see if it falls off. calling for rain all weekend. sucks. truck does not see the rain, snow or ice.

I would suspect fuel flow with no pressure (line unhooked test method) -vs- one under pressure would be 2 different animals. not sure your loose line tests are valid IMO.

 

[Quickstop [UK]]

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

bummer dude - hope you get it fixed

 

[1madgumby]

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

Took it for A ride today. Was at 50 psi. until like 10 pounds of boost then the fuel psi dropped back down to 50 and stayed there. PUMP ??

 

[BoostedSUV]

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

Definitely a fuel volume issue. Could be pump or regulator... Definitely an issue if you're losing fuel pressure under power.

 

[1madgumby]

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

what do you think, pump or Reg. or both.?

Definitely a fuel volume issue. Could be pump or regulator... Definitely an issue if you're losing fuel pressure under power.

 

[BoostedSUV]

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

what do you think, pump or Reg. or both.?

I would think pump but test the regulator. If you have the ability connect the fuel pump test lead to power with the truck off and watch the gauge. Take an air compressor with a regulator and set air PSI to 20 and connect it to the vac port on the regulator. The fuel pressure should raise 20lbs... That's a good way to test the regulator since the injectors won't be firing so the fuel pump be able to sustain pressure and volume. That could potentially eliminate the AFPR as the problem.

You didn't kink a line on the sending unit when changed the pump did you?

 

[1madgumby]

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

Did not think of that will try that tomrrow, no I did not kink anything.

I would think pump but test the regulator. If you have the ability connect the fuel pump test lead to power with the truck off and watch the gauge. Take an air compressor with a regulator and set air PSI to 20 and connect it to the vac port on the regulator. The fuel pressure should raise 20lbs... That's a good way to test the regulator since the injectors won't be firing so the fuel pump be able to sustain pressure and volume. That could potentially eliminate the AFPR as the problem.

You didn't kink a line on the sending unit when changed the pump did you?

 

[BoostedSUV]

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

That's exactly how I tested my regulator.... Creates the same effect as being under boost with out risking motor damage. However if your fuel pressure did rise and fell off as boost increased I would think its a fuel pump delivery issue. Check the regulator anyway before you start throwing money at guessing.

 

[dgoodhue]

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

Usually when FP regulator dies, the bladder inside them rips, you will smell fuel in the vacuum line going to it. I would put money on the fuel pump if you don't smell gas in you vacuum line.

 

[BoostedSUV]

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

^i agree but it doesn't hurt to take 5 mins to be sure the AFPR is functioning properly. Like I said, if the fuel pressure did rise intitially then started tapering off as boost increased I would say the pump is not providing enough fuel for the motors demands. Obvioulsy the higher the boost and more throttle you give, the more fuel the truck is going to use. It appears to me that the pump is not pumping enough volume to keep up with demands....