feifongwong3 Posted March 27, 2012 Share Posted March 27, 2012 Ok, RB gurus, I have an 83 S130 with a brand new walbro 255, RB20, and nismo adj. fpr. The problem is when I key up, the fuel pump comes on, but as soon as I lower the pressure as read by the gauge, the needle goes wild from about 20 psi to 50 psi. My filter is new also, but my fpr might be fubar. The "top hat" section of said fpr spins, so I'm figuring that it might be the prob. Please advise. Quote Link to comment Share on other sites More sharing options...
djz Posted March 27, 2012 Share Posted March 27, 2012 What are you trying to set the pressure to? Quote Link to comment Share on other sites More sharing options...
feifongwong3 Posted March 27, 2012 Author Share Posted March 27, 2012 Just 3 bar, you know stock pressure. Quote Link to comment Share on other sites More sharing options...
wrcbonk Posted March 27, 2012 Share Posted March 27, 2012 Sounds like the pump is getting jerked around by either the ignition signal or the fpr. I think your Walbro pump is fine. Assuming the Walbro Pump adjusts automatically for the required pressure (3 bar) like the Bosch 044. Pumps are pretty simple, they either work or they don't, I doubt there is anything going on there. So either the fpr regulator is bad or the signal coming from the ignition system powering the pump is bad (doesn't jive with the pump). Are you using any part of the Z31 harness to drive the pump? If so I would research how the stock (Z31) ignition system operated the oem electronic fuel pump. See if there are differences in how your system operates. I am using the stock fpr that came with my engine (R33 RB25). I am running a stock replacement (ebay cheapy) nissan RB fuel pump. I am powering the fuel pump through the RB harness and relays. No problems YET! Also check your ignition switch at the key (volt meter). Those switches do go bad. Bonk Quote Link to comment Share on other sites More sharing options...
feifongwong3 Posted March 27, 2012 Author Share Posted March 27, 2012 No, I'm not using the original harness to run the pump. It had to be modified, but I have a full 12v at the pump. But, otherwise I agree and think its the fpr and I'll have to make a trip to Courtesy Nissan and pick up another fpr or source a different one. Any recommendations on a different fpr? Quote Link to comment Share on other sites More sharing options...
wrcbonk Posted March 28, 2012 Share Posted March 28, 2012 I would create a "Parts Wanted" thread for a used stock fpr. You want to get a fpr from someone who used it in their car and then replaced it with an adjustable. You want something that you know has worked before. You can use it to eliminate the fpr from the problem. I went to RockAuto.com and searched for the fpr for a 1994 300zx, it looks strangly similar to the one on my car. The infiniti J30 is listed as a car using the same part. Prices varied from $60 to $90. I would confirm the part # before ordering, but I will be surprised if it isn't the same on used on RBs. Your other option is to go Aermotive. You will need to invest in some pricey AN fittings and replumb some stuff. It is adjustable. I will probably buy one some day after I buy a programable ECU, but until that day, its stock parts for me. Bonk Quote Link to comment Share on other sites More sharing options...
feifongwong3 Posted March 28, 2012 Author Share Posted March 28, 2012 The only problem with that is the fpr for the 25 is definitely different from the 20. No bracket on the 20 fpr, well not like the 25's. Check out the Nismo type a adjustable compared to the type b and you'll see what I mean. But I do see your point in posting in the wanted section. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 28, 2012 Share Posted March 28, 2012 The S30 EFI cars have a fuel damper that absorbs high frequency pressure variations. S130s probably do also. They are adjustable. Maybe yours needs a tweak to match the non-OEM pump. It's in the same vicinity as the pump and looks kind of like an FPR, with a bolt on the top. Quote Link to comment Share on other sites More sharing options...
feifongwong3 Posted March 28, 2012 Author Share Posted March 28, 2012 Yeah, my s130 has one,but I was under the assumption that they were set at the factory and not adjustable. That was one of my thoughts, but had pushed it aside when I found out that changing the damper setting could be detrimental to my fuel system. Quote Link to comment Share on other sites More sharing options...
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