Ben's Z Posted August 19, 2013 Share Posted August 19, 2013 I finally got my AEM UEGO hooked up yesterday and my AFR's were initially a little erratic. As the car runs for a few seconds the wide band shows AFR's between about 14.5-16, and sometimes it completely stops reading momentarily (goes way lean) and then goes back to that same readings. I just put my fuel pressure gauge on and it was reading 21 psi with the vacuum hose attached and 30 psi with it off. Obviously this is symptomatic of a bad FPR. However could a vacuum leak cause this low of pressure? I thought I saw somewhere that a NA FPR was the same as a Turbo, however the FPR off my 77 set up has two feed lines and the Turbo one on the car now has 1 feed, 1 return and 1 vacuum. Quote Link to comment Share on other sites More sharing options...
Ben's Z Posted August 19, 2013 Author Share Posted August 19, 2013 I am going to pull the sending unit tonight to get a peak inside the tank. I suspect it could be crusty in there. I am also going to clean the pump strainer and blow air through the lines to see if this ups the fuel pressure. Quote Link to comment Share on other sites More sharing options...
Akira Posted August 19, 2013 Share Posted August 19, 2013 I just put my fuel pressure gauge on and it was reading 21 psi with the vacuum hose attached and 30 psi with it off. Obviously this is symptomatic of a bad FPR. Isn't this normal? You set the FPR with the vacuum off. It should read lower with the vacuum on. Quote Link to comment Share on other sites More sharing options...
ryan95i4 Posted August 19, 2013 Share Posted August 19, 2013 Isn't this normal? You set the FPR with the vacuum off. It should read lower with the vacuum on. The stock FPR isnt adjustable, there isnt anything to set. I *think* the concern is the low fp, not the difference b/t pressure w/ and w/o vacuum. If the there are no blockages in the line and you suspect the FPR, i have a like new stock fpr I dont need, shoot me a PM. Quote Link to comment Share on other sites More sharing options...
Ben's Z Posted August 20, 2013 Author Share Posted August 20, 2013 (edited) Tank was pretty yucky inside. Oddly enough the tank must have been repaired or boiled out before because it had a metal tag on top of the tank of a radiator repair shop here in Houston. I am going to call them tomorrow to see if they can tell me what they did and when. Edited August 20, 2013 by Ben's Z Quote Link to comment Share on other sites More sharing options...
mattb3562 Posted August 30, 2013 Share Posted August 30, 2013 If the chemical used is not catalyzed, it will, from what I've seen, breakdown over time by the fuel and either turn gummy, or break off in chunks in the tank. Make sure you have a clear filter installed between the tank and pump. And if the fuel looks odd, have it tested. The tank may need 'recleaned' and properly coated. Like anything else, there are quality chemicals vs cheap chemicals that coulda been used in your tank. Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 30, 2013 Share Posted August 30, 2013 "Obviously this is symptomatic of a bad FPR." Thanks for that. Made my night! You kill me man... Quote Link to comment Share on other sites More sharing options...
Ben's Z Posted September 1, 2013 Author Share Posted September 1, 2013 (edited) "Obviously this is symptomatic of a bad FPR." Thanks for that. Made my night! You kill me man... Hey *EDIT*, Thought you had me blocked. Anyhow, I called the radiator shop and they said they would have coated the tank internally. I flushed it out with purple power and let it dry. (Their advice) I put in all new rubber EFI line and blew compressed air with paint thinner through the feed line from the engine bay to the rear of the car. I installed a Wix clear inline fuel filter between the tank and pump and a new filter in the engine bay. Interestingly my pump was much quieter however my fuel pressure remained unchanged with all this work. I believe the pump might be a little weak. It took about 10 times of cycling the ignition to get enough fuel to fire the engine. Even the clear inline filter was barely filling after a fuel ignition cycles. I may order a Walbro 255 which is necessary for my power goals anyhow and a new OE FPR. Still showing 21psi at idle with 30 psi with the vacuum line removed. Edited September 2, 2013 by RB26powered74zcar Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.