High FP after installing new Wally 255 hp.

[Staytuned]

Today I took out my old non rewired Wally 255 lph fuel pump....it just wasn't up to the task of 30 psi anymore. So in goes the new 255 lph hp pump and a rewire kit. Now I can't get my FP to drop below 45-46 psi. I have the AEM universal fuel pressure regulator with the largest return orifice in it. I have -6 fuel lines from the pump up to an Aeromotive fuel filter, which then leads through a stock fuel rail then onto the FPR. I have stock return lines back to the tank.

The fuel pressure was very adjustable before the swap.


Are the stock return lines that restrictive or have I missed something else here??

 

[romeen]

Did your FPR come with two different springs? Maybe the spring you are using is too stiff.

Also, when you did the install did you alter anything with the EVAP system? If there is too much pressure in the fuel tank it might cause increased pressure in the entire system. Remove the fuel filler cap and see if releasing the pressure makes any difference.

Make sure there are no kinks in the return line.

 

[1992awdlaser]

2g awd with high fuel pressure and adjustable regulator= siphon tube in the tank.

The siphon needs to be drilled out. Even if you put on a -10an return it would still have high pressure. The 2g awd's have a saddle tank and the siphon is what helps gas get from one side to the other to keep it level in both sides.

 

[Staytuned]

Did your FPR come with two different springs? Maybe the spring you are using is too stiff.

Also, when you did the install did you alter anything with the EVAP system? If there is too much pressure in the fuel tank it might cause increased pressure in the entire system. Remove the fuel filler cap and see if releasing the pressure makes any difference.

Make sure there are no kinks in the return line.

One spring only with this kit......no pressure in the tank at all because I had the gas cap loosened off when installing everything.

No kinks in the return line at all.

2g awd with high fuel pressure and adjustable regulator= siphon tube in the tank.

The siphon needs to be drilled out. Even if you put on a -10an return it would still have high pressure. The 2g awd's have a saddle tank and the siphon is what helps gas get from one side to the other to keep it level in both sides.

This I will have to investigate.

 

[Burnett03]

Like said above, remove the fuel pump and drill out the siphon with a 1/8 bit.. I believe it's 1/8 it's been a while since i did mine.. It made my fuel pressure drop.

 

[gsxtasy]

2g awd with high fuel pressure and adjustable regulator= siphon tube in the tank.

The siphon needs to be drilled out. Even if you put on a -10an return it would still have high pressure. The 2g awd's have a saddle tank and the siphon is what helps gas get from one side to the other to keep it level in both sides.

This is the problem. Although, I could run stock pressure with my single rewired 255... however with my inline pump as well I couldn't. I drilled out the siphon with an 1/8'' drill bit and now i can run as low as 30psi.

Edit: Burnett beat me to it.

 

[Staytuned]

Ok where is the siphon tube exactly ...... bottom of the fuel pump assembly unit?


Any pics of what I am looking for would be great?

 

[DSMunknown]

http://www.dsmtuners.com/forums/newbie-forum/259430-fuel-tank-must-hold-pressured-vapors.html

 

[Staytuned]

http://www.dsmtuners.com/forums/newbie-forum/259430-fuel-tank-must-hold-pressured-vapors.html

The tank holds pressure fine, that's not the problem. The problem lies in the fact that my return line is too restrictive now or that siphon tube is too small.

 

[gsxtasy]

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**These pics are courtesy of newdsmman on the dsmlink forums, hope he doesn't mind.**

You drill out the side that goes straight through, if it wasn't obvious from the pics. It's located right next to the fuel pump, if you take out your assembly, you will easily see it.

 

[Staytuned]

Thanks so much for your help .... I will get at that next week when I get a chance.

Any harm in drilling it out larger than that you think?

 

[gsxtasy]

Thanks so much for your help .... I will get at that next week when I get a chance.

Any harm in drilling it out larger than that you think?

Yes, you will lose the proper ratio of fuel coming in to create a good enough vacuum to suck any fuel out of the driver side saddle. Pretty much if you go too big you'll run out of fuel at a quarter tank or so on the gauge.

Use a 1/8'' drill bit, that's about as big as you want to go, and it will be more than enough.

 

[Staytuned]

Cool thanks again gsxtasy.

 

[gsxtasy]

No problem, glad to help!

 

[Staytuned]

Well almost a year to the day I finally got around to drilling out the siphon tube and it for sure solved my issue, I now have a base FP of 43.5 psi without issues at all.

Thanks again GSXtasy.

 

[turboglenn]

I agre with everyone else about he siphon tube, but one other thing you might want to do while you're playing in gas next time is to use the factory feed line as a return, I cut mine off a few inches past the OEM filter hook up then put fuel hose on it and ran it to the AFPR. Then at the rear of the tank you have the option of either adapting over with metric to AN fittings or just cutting the end off the OEM line that hooked to the fuel out on the hanger and clamping it over the return line in the hanger.

I have a FWD so i didn't have to worry about the siphon tube, but i was getting too high of pressure due to the OEM return line it's self and solved it as described above

 

[Staytuned]

Way too late to do that as I took the factory feed line out completely when putting in the -6 line.

Thanks though for the advice.