On a separate note, which '280 cams' are these?

 

bc 280s

and ill double check the fuel lines again for any kinks or tight bents to make sure theres nothing like that happing. i have a fitting like that for a gauge i found in my shop that a buddy has so ill pick up a gauge n see if there is a pressure problem.

do you think the tune needs to be changed to fix the problem or do you think its more serious then that. it was a good 11.8 afr under wot now its about 13.3-13.5 ...... i dont wanna just tune around it so then wen its dyno time n the next 2 weeks im not cut short or disappointed cuz there problem was more then that. but i wouldnt think this should be happening from adding the things i did

 

There is no way anyone can know the answer to that question from this perspective. If the FP does not keep up with manifold pressure, it's a fueling issue. If it rises as expected, it would appear to be a tuning matter. I'd guess the former, but who knows? At least with a pressure gauge, you will know one way or another, both now and in the future.


I was afraid you might say that. Fueling isn't the only thing that's going to keep you from making power up top. - Just FYI

 

ya i know they arent the best 280s out there but there gunna have to do for now.

on a side note i double checked over everything befor taking the car out and i noticed befor that on my volt gauge on a pull and higher rpms would read 16volts and now that i have the power from the battery going to both pumps car hold a consistent 14 all the way through the pull to redline. could the differnce in volts effect the injectors/tune up top by chance??

 

Just keep in mind that there will likely be another 50whp or so to be found with a better cam set.

Will a difference in voltage at the pump create a change in pump output? Absolutely.

Will it make a difference?

That depends. If the original setup overran the return system, yes.

 

what do you suggest for a set of cams then?

with the high voltage the car did befor at higher rpms which it doesnt now with 2 pumps you think a single walbro could over run the stock return? siphon wasnt drilled then either i just did that when 2nd pump was installed

 

For a 2.3-2.4, I suggest a set of GSC S2 or Kelford 280.

A Walbro 255lph HP pump at 20psi boost flows about 290lph at 16.5V.

A Walbro 255lph HP pump at 20psi boost flows about 235lph at 13.5V.


I'm not saying that represents the difference, but neither can I say that it wouldn't be a factor.

I'm not sure how/why you'd be seeing 16V on the gauge, but that isn't necessarily what the pump is seeing. One thing you can do on a dyno, or with someone in the back while making a road test, is check the voltage and ground at the pumps while under load. That is where you'll find how capable your power/ground wiring is.

 

How were you seeing 16V before? You didn't have a boost-a-pump or something like that, did you?

The difference in voltage may be your isse, but as Ted mentioned, there are too many other variables to know for sure.

 

you know once i put the motor back in the car after the build i just noticed on the volt gauge it would climb that high as rpms wen up for some reason.

there was no pump rewire or booster wiring when it was single pump i just sis that stuff wen installing dual pump now volt hold at 13.5-14ish all the time. so i kinda leaning towards that is my issue.

 

Yeah, as TedB says get a fuel pressure gauge. Either run one off a fuelrail shraeder valve fitting and duct tape it to your windshield or install it in the cabin with an electronic sender.

Test both pumps individually and then both together inline to see if they each deliver the requisite 255 LPH. Disconnect the feed line and puke it into a meaured bucket. How many Liters per minute?

 

Are you using the stock fuel feed return line or did you run a separate AN-6 line? Have you considered that if you're using the stock return line; which is pretty small, you might be creating back pressure and thus the lean condition. Wondering if excessive back pressure would cause your lean condition. Just a thought... 30% more fuel with E85, 30% larger fuel lines. More pressure up top, more flow.

 

all this thread needs is a fuel pressure gauge... and then go from there

 

well, I installed a fuel pressure gauge and it read right around 40psi at idle then dropped as low as 20psi under boost. I can upload a vid if need be.

 

I don't see why making a video would be necessary. It's obvious that something is FUBAR.

This is a new installation, so the likelihood that human error is the cause is high. It would seem that one pump isn't running, there is inadequate voltage to at least one of the pumps, there is an obstruction in the line, or the FPR is toast (least likely).

I'm not sure what else anyone here can do. If no obvious answer can be found upon visual inspection, you'd want to read voltage going to the pumps while under load.

 

is there anyway i ****ed **** up drilling the siphon somehow thats causing this issue??? tested the pumps and both are 13.0-13.5 volts at idle i didnt have time tonight to check while doing a pull i will do that tomorrow