well today i tackled my dual pump install on the evo and befor i did car was single walbro stock lines ams rail and stock fpr and ran great and now after installing my dual set up car goes lean up top now. set up now consist of intake walbro feeding inline walbro and -6 line to ams rail with stock fpr and return line and i drilled the siphon too today with the 9/64 bit. any ideas would be helpful! thanks

 

What have you checked so far and ruled out as a problem?

 

what are you doing for power to each pump?

 

Something is amiss.

The obvious possibilities:

- One pump is not running.
- Power and ground wiring to the pumps is inadequate

 

i have pretty much checked over everything as far as wires and pumps and for leaks but no such luck on finding a problem. the only thing that i can think of right now is befor when tuned on single pump i didnt have the siphon drill with the 9/64 bit like ted b says to do. and now i did that and idk if that would open the return up more as where it would drop the fuel pressure which causing the problem of going lean up top if thats possible.

 

you could have a 2" return and it wouldnt drop fuel pressure.

 

i have them both powered buy 16g power wire from the battery to a relay. both have the stm re-wire kit and wired the same so no pump should be getting more power then the other.

 

A means of viewing the FP at the rail while the engine is under load (boost) would be very helpful in troubleshooting this situation.

At this point, we do not know if you have inadequate pressure now, or, if you had an excess of pressure before.

Also, ground wiring is as important as the power wiring.

 

ya see then that rules out the only thing i could think of. i dont under stand how it ran good with one pump and now with the added pump and bigger line the fuel supply should be there but its not if its going lean. doesnt make sense to me

 

and you are sure both pumps are getting plenty of power? fuel filter good? if you recently switched to e85 the filter could be clogged.

 

car has always been on e85 since single pump...... lookin for more power and thats the reason for adding the second one. as for power i would assume they are gettn the same and good power straight from the battery.


i have never veiwed the fuel pressure on the car since its still stock fpr. i was under the impression i was going to have higher for the dual pump n stock return but i dont see how the second pump would cause it to lean out now with fine befor pump and siphon dill was only thing added.

for the grounding i just took a mini grinder and made a clean bare metel spot under the seat by the pump locaton and self tapped the ground wires down there

 

We're guessing here because we cannot see what is happening with the FP. Until you can do that, it is a bit like feeling in the dark. If you're intent with sticking with the factory FP, you can probably tap that AMS rail for a 1/8 NPT fitting, or, you can fit an inline AN-6 fitting that includes a 1/8 NPT tap (Earl's). That allows you to fit a guage when necessary. And since fuel pumps don't last forever, it's not a bad thing to be able to check the FP under load.

We know that IF both pumps are running (in the same direction anyway), you should not have an FP issue 'at the top', especially if no such issue existed with a single pump.

Also, we don't know anything about your car, nor what your fueling demands are at this moment. That may be helpful.

 

good point!

 

right now car is 2.3 bottom end built head, 280 cams, 1mm oversize valves, springs n retainers, with a forward facing 6262 setup. i have it street tuned right now very safe befor i go the dyno in 2 weeks so for the power im hoping on making on e85 the second pump was guna b a must.

are you think its a pressure problem do to the going lean up top under load?

im jus racken my brain right now how just adding another pump bigger line and drilling out the siphon would cause this since the fuel demand hasnt changed from when was still single pump and now there should be more fuel there at the rail.

 

That shouldn't be the problem, but unless there is a way to view the pressure, there is no way of knowing. Sometimes an extra $25 and an hour or two of time is worth the effort.

I'd think about getting one of these (whichever is appropriate - in stainless if available):
http://www.summitracing.com/search/?...0fitting&dds=1

And something like a Marshall liquid-filled gauge for a permanent fixture:
http://cgi.ebay.com/ebaymotors/Fuel-...Q5fAccessories

You can make an extension line if you need to view the gauge from inside the car while testing.