bernie lomax Posted October 6, 2012 Share Posted October 6, 2012 Hi, my stock L28e fuel pump failed & I decided to upgrade to a Walbro GSL-392 unit. Everything else on the car is stock & it is non-turbo (for the time being). My question is what should the proper fuel pressure (psi) be for the Walbro pump? I have a fuel pressure gauge taking readings before the fuel pressure regulator & with the stock pump it was also pretty steady at 30-35psi before it died. With the Walbro installed, I now see readings of 90psi which can fluctuate down to 40 psi. The pump is also making an oscillating, siren like noise as if it is laboring heavily & it is very hot to the touch (hotter on the fuel output side than the input side). Volt reading at pump terminals varies between 9.5 - 10.4vdc when it is making the noise. It may then run quiet for a while with pressure at a steady 40psi & only warm to the touch, with volts at a steady 10.1vdc. It almost seems like the pump is labouring trying to pass a "kidney stone" or some type of blockage. My worry is that I am slowly burning out the pump. I only let it run for approx. 5mins like this in the driveway. Wanted to confirm the psi reading that a Walbro GSL-392 should produce before the regulator. Any help/suggestions is appreciated. Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 7, 2012 Share Posted October 7, 2012 Should be identical to stock pump unless the pumps capacity is overwhelming the line or regulator orifices... Hi flow pumps sometimes have trouble keepin idle pressure low, as low horsepower fueling demands were not in the engineers list! Good luck! Quote Link to comment Share on other sites More sharing options...
NewZed Posted October 7, 2012 Share Posted October 7, 2012 Are you using an aftermarket regulator? You might have the inlet and outlet reversed, at the regulator. That will deadhead the pump as the gasoline pushes on the wrong side of the valve and the pressure will go to maximum, which is about 90 psi for many aftermarket pumps. I did it with an Aeromotive regulator and an Airtex pump. Started and ran really rich before I realized my mistake. Quote Link to comment Share on other sites More sharing options...
Xnke Posted February 1, 2013 Share Posted February 1, 2013 Also sounds like a failed stock regulator...I have no idea how the bosch regulator fails locked closed, but I have had it happen and another member here had it happen...I had exactly the same symptoms but the pump would actually get hot enough to lock up and quit until it cooled off. Quote Link to comment Share on other sites More sharing options...
motomanmike Posted February 1, 2013 Share Posted February 1, 2013 http://forums.hybridz.org/topic/110054-external-walbro-fuel-pump-issues-not-priming-right/ I had a very similar issue an it was the regulator that failed Quote Link to comment Share on other sites More sharing options...
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