Challenger Posted June 21, 2010 Share Posted June 21, 2010 (edited) My 81 turbo will be running the stock ecu with the aid of a Begi FMU. In order to run increased fuel pressure I bought a 255lph walbro high pressure fuel pump. Problem that presented itself was a bit of overpressurizing. With the stock regulator and fuel pump I run the correct fuel pressure in boost, about 42 psi. In this condition the engine seems to run well. When the new walbro is put on still using the stock regulator I get fuel pressures in the range of 50 psi. This makes the engine run very rich as expected. Anyone have any ideas on how to fix this? The stock regulator works well with the stock pump, so I dont think its the regulator. Is it possibly the return line going to the tank is too small, or even the lines going to fuel rail? Also, forgot to mention, I havent installed the FMU yet and I dont expect installing it would give me the proper fuel pressures I needed... or would it? Thanks Edited June 21, 2010 by Challenger Quote Link to comment Share on other sites More sharing options...
Zmanco Posted June 21, 2010 Share Posted June 21, 2010 Strange, I'm running with the stock FPR and a walbro 255 and the FPR doesn't have any problem maintaining pressure. Have you double checked that the vacuum line to the regulator is still intact? I don't know what the max input pressure is for the FPR, but it's hard to imagine that the walbro is exceeding that, unless the FPR is defective. Do you have a spare FPR you can swap in? Quote Link to comment Share on other sites More sharing options...
Challenger Posted June 21, 2010 Author Share Posted June 21, 2010 Yeah Ive got another one Ill put on, Im just not sure why it would be the regulator if it works fine but who knows. Now that I think about it, im going to try a different fuel filter. The one on there now is a plastic clear filter meant for carbed cars, aka really low fuel pressures. Ill switched it out with a fuel injection one and see if that helps. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted June 21, 2010 Share Posted June 21, 2010 I can't see how the filter would cause the pressure to be too high, but nonetheless, I wouldn't want a low pressure filter in a FI car. leaking fuel = bad things happening If the other FPR doesn't solve it, you might want to temporarily install the pressure gauge before the FPR to see what the outlet pressure of the walbro is. Quote Link to comment Share on other sites More sharing options...
Challenger Posted June 21, 2010 Author Share Posted June 21, 2010 The current system is fuel pump to filter, to fuel rail, T's off to the gauge and the FPR and then back to the tank through the line that went to the FPR. So it is before the regulator already. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted June 21, 2010 Share Posted June 21, 2010 You're correct, my mistake, I forgot that the FPR is AFTER the injectors on the Z. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted June 21, 2010 Share Posted June 21, 2010 You must have a restriction in the return somewhere, and maybe in the regulator. Quote Link to comment Share on other sites More sharing options...
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