Installed Walbro now some problems!

[Angry7M]

So yesterday morning at work, I installed my brand new Walbro 255lph fuel pump that I bought from horsepowerfreaks. At that time I hadnt bypassed the Jtube, so after a 30 min drive home, as soon as I slowed down to about 10 mph in first gear, I noticed that the car started to yank back N forth a little. And also during my 30 minute drive home If I accelerated I noticed a little lack of throttle response, althoufh at WOT I felt fine. It didnt do that when I disconnected the vaccum source from the fpr, with the old pump.

So today I decided to check the Fuel Pressure with my gauge, before bypassing the Jtube. After hooking up my gauge I noticed that all the fuel reading were the same as before with the old pump which was good. But as soon as I unhooked the vaccum line to the Stock FPR the PSI just went down and started fluctiating from 25 to 28 psi, and it didnt go up.

Also I didnt do the 12 Volt mod, I take it this is my problem, and its probably that it needs the 12 volt mod to work correctly?

FP and B+ jumped (engine off)= 38 PSI

Idle= 28 PSI

Idle with Fuel pressure regulator dissconnected= Fluctuating from 24-28 psi.

Is this my fuel pump wiring?

Thanks

(Edit: Today I bypassed the Jtube and the Fuel pressure at idle went down to 24 psi)

BTW my fuel system is basically stock....

 

[jdub]

FP and B+ jumped (engine off) - FP should be 33-40 psi.

Engine on, vac line removed from FPR - FP should be 33-40 psi.
(this sounds like the main problem)

Engine on, vac line attached to FPR - FP should be 23-30 psi.

FP should stay at 21 psi or above for 5 minutes after the engine is shut down.

I've read where the Walbro does not like to run at 12V, but have not experienced that issue myself...my Walbro runs fine with the resistor supplying 9V. A easy way to check is to pull the resistor connector and jump it on the harness side with a 12GA wire....you'll have to flatten the wire with a hammer and file to make it fit the pin connectors. The FP will run at 12V at all times with this connector jumped.

Personally, I suspect your FPR is having a problem handling the additional flow from the Walbro.

How/where are you checking FP?

 

[Angry7M]

Well today i did the 12V mod I jumped the Fuel Pump Relay and eliminated the Resistor just to test and see what happens. So I hooked up the Fuel Pressure Gauge and at idle it read 31 psi (higher then normal). Then I unhooked the Vaccum source from the FPR and the psi went up (which is good, I dont remember how much though).

Ok, so at this point im like "cool". But then I pinched the FPR return line and the PSi went from 31 psi to 51 psi, then after I unpinched the Return line the PSI stayed at 51 psi and didnt go down. So basically I need a new Few Pressure Regulator, im looking for a AFPR hopefully i can find one for cheap.

And hopefully I dont have to use this 12Vmod after I get the FPR.

All these test were done with the Jtube bypassed

Also when I shut off the engine I loose Fuel Pressure very fast, this has happend even before the walbro install, its probably the FPR.

And I was measuring the fuel pressure with a hose hooked up to the rail, to where the CSI line goes.

 

[shaeff]

Are you sure the gauge wasn't sticking?

 

[Angry7M]

Are you sure the gauge wasn't sticking?

Yup im sure, when I hooked up the relay and resistor, it went down to 20 something PSI at idle (again).