Enlight Posted November 2, 2021 Share Posted November 2, 2021 I have an AP and didn't know it could log, shows how much I know. Only reason I mention it is because I'm on my own journey to keep my hands off the parts cannon - the logs will probably give you some clues. muFreight.co A JDM Container Sharing Service from Japan to NYC Website | Instagram | Email Bessie II's Thread Link to comment Share on other sites More sharing options...
Tehnation Posted November 2, 2021 Author Share Posted November 2, 2021 (edited) OK! So i was talking with a mechanic friend of mine, and he's like test the pump, just disconnect the line and see what happens, and I'm like YEAAA good idea before I start pulling the pump apart etc. So I started the car today for the 1st time like usual fired right up from like 22-23psi of pressure on the line. I let it run until it dies, then I release the pressure in the system, prime it again and it goes back to the 22-23 psi, but doesn't start. So I disconnect the line again put it in a bottle prime it and it just does one prime, basically it squirted out like an 1/8 or so liter of fuel then just stops. Now my question is why doesn't the pump keep priming? It just does one single push and then no more pressure is in the line after that. Isn't the pump supposed to keep priming? Or is it supposed to do the one push? If its supposed to keep constant pressure while priming then I found my answer! My fuel pump is not pressurizing the line past the one prime it does and then just does nothing after that one gush. Is that the way its supposed to operate? Someone PLEASE tell me this is a fuel pump issue or something is going on in the tank. At least I have narrowed down the problems. I don't want to add fuel until I get a better idea of whats going on. Edited November 2, 2021 by Tehnation Link to comment Share on other sites More sharing options...
Tehnation Posted November 2, 2021 Author Share Posted November 2, 2021 (edited) Does 22psi seem to low to prime the system? If it idles at like 34-37psi, shouldn't it prime around that? Edited November 2, 2021 by Tehnation Link to comment Share on other sites More sharing options...
Infosecdad Posted November 2, 2021 Share Posted November 2, 2021 It idles at 42psi, should prime around 35psi. It might be an o-ring, but if it gets worse as it warms up, could very well be the pump failing. Link to comment Share on other sites More sharing options...
Tehnation Posted November 2, 2021 Author Share Posted November 2, 2021 So I need to test/inspect the fuel pump and fuel pump control module. I think I need to start looking at duty cycles or other fueling stats with the accessport. I gotta figure out how to test the fpcm and pump.... Link to comment Share on other sites More sharing options...
Infosecdad Posted November 2, 2021 Share Posted November 2, 2021 What's the background on your fuel pump? When mine was overheating and losing pressure, I just replaced it. Because by the time I tore into everything, I didn't care if it was just the o-ring, I didn't want to go back any time soon. So new o-rings and new pump. Link to comment Share on other sites More sharing options...
Tehnation Posted November 2, 2021 Author Share Posted November 2, 2021 Its an AEM 50-1215, has less than 150 miles on it and was installed about 1.5 years ago. I did the upgraded wire gauge/direct battery connection mod with the relays etc. Link to comment Share on other sites More sharing options...
Tehnation Posted November 3, 2021 Author Share Posted November 3, 2021 Tuner says if its connected to the fpcm it should only prime once! So thats normal, so I'm thinking its not putting out enough pressure. Link to comment Share on other sites More sharing options...
whitexc Posted November 3, 2021 Share Posted November 3, 2021 No leaks, odors or other signs it may be losing prime or struggling to prime? Sounds like its time to R&R the pump assembly. Sent from my SM-G996U using Tapatalk Link to comment Share on other sites More sharing options...
Tehnation Posted November 3, 2021 Author Share Posted November 3, 2021 so it seems lol. Tuner said it should be 43 psi base pressure thats with the regulator vacuum line disconnected. 22-24 is way to low. I think I don't have enough pressure.... gotta check those o rings! I'm pretty sure I used 2... hmmm maybe not.... Let the gambling begin! Place your bets whether I have 1 or 2 o rings installed! Link to comment Share on other sites More sharing options...
whitexc Posted November 3, 2021 Share Posted November 3, 2021 Following. Not a gambler.....although I do own a Subaru [emoji23] Sent from my SM-G996U using Tapatalk Link to comment Share on other sites More sharing options...
Tehnation Posted November 3, 2021 Author Share Posted November 3, 2021 (edited) Oh god, now I know why I have been trying to avoid messing with the pump. Got it out and have been fiddling with this thing for about an hour trying to get the pump out of the housing..... is there tool? I'm done with this nonsense design. Its beer thirty! Edited November 3, 2021 by Tehnation Link to comment Share on other sites More sharing options...
Tehnation Posted November 3, 2021 Author Share Posted November 3, 2021 There really isn't a tool out there, wow! You would figure some nerd would have come up with something years ago, being that the fuel pump is a major mod, and one of those parts that always seems to fail. Link to comment Share on other sites More sharing options...
Infosecdad Posted November 3, 2021 Share Posted November 3, 2021 Oh god, now I know why I have been trying to avoid messing with the pump. Got it out and have been fiddling with this thing for about an hour trying to get the pump out of the housing..... is there tool? I'm done with this nonsense design. Its beer thirty! https://cobbtuning.atlassian.net/wiki/spaces/PRS/pages/51839019/315400+-+COBB+TUNING+HIGH+FLOW+FUEL+PUMP That should help you with getting it out and back in again. Link to comment Share on other sites More sharing options...
Tehnation Posted November 3, 2021 Author Share Posted November 3, 2021 I was just stuck on the stupid clips, learned that two small flat heads works the best and easiest, the smaller the better. I think I found the problem. Not even gonna risk it, going to put in the new one, and send the other back to aem cause it should be in warranty. Link to comment Share on other sites More sharing options...
Tehnation Posted November 3, 2021 Author Share Posted November 3, 2021 A god damn o ring failure........ really...... a 2 cent item...... Link to comment Share on other sites More sharing options...
rhino6303 Posted November 3, 2021 Share Posted November 3, 2021 I've found that you have to be very delicate when installing the pump in the housing or the o-rings break upon install. Who knows, that could have been the reason for previous engine issues. Link to comment Share on other sites More sharing options...
Infosecdad Posted November 3, 2021 Share Posted November 3, 2021 Yup, that is one shot o-ring… Don’t blame you on replacing while there, that’s not my favorite thing to do for sure. Link to comment Share on other sites More sharing options...
Tehnation Posted November 3, 2021 Author Share Posted November 3, 2021 I've found that you have to be very delicate when installing the pump in the housing or the o-rings break upon install. Who knows, that could have been the reason for previous engine issues. It was fine last year, sat for a year, worked fine this year for 20 miles then failed miserably. I've been through a bunch of pumps prior, Walbro, DW and the AEM, haven't had any issues with install, so I don't think that was the issue. It blew out right at the seam. The previous issue was just the tune, as soon as I got the accessport, the tuner was able to give me a nice base tune for the stage 3 cams, and the car ran great until the tensioner went. They said they couldn't tune using opensource with my cams, which is why I bought the accessport. Link to comment Share on other sites More sharing options...
Tehnation Posted November 3, 2021 Author Share Posted November 3, 2021 (edited) Now everything smells like gasoline.... Looks like sitting for a while made the washer brittle, cracked in 2 places. Edited November 4, 2021 by Tehnation Link to comment Share on other sites More sharing options...
Tehnation Posted November 4, 2021 Author Share Posted November 4, 2021 (edited) Whats funny is I have never used 2 o rings prior to the AEM pump, and never had an o ring failure. For all the other pumps I only used one. The pump doesn't go in flush, the plastic piece it goes into has 4 nubs which is another spacer for the head of pump. So if you subtract that height + the height of the spacer from the height of the pump head shaft, we should be able to determine whether 1 or 2 washers should be used. 2 o rings might be putting to much tension/compression on the system causing them to stretch/deform out of spec. Example, if you have 3 mm of space, and a 2 mm O ring, rather than just leave the 1mm of space, we are putting 4 mm worth of O ring, if that makes sense. That O ring in my opinion is supposed to act as a simple seal and is not meant to be compressed. Just a thought, I emailed tuner to ask how many o rings they use. Conclusion, I think the flaw in that pump design is the spacer. Edited November 4, 2021 by Tehnation Link to comment Share on other sites More sharing options...
Infosecdad Posted November 4, 2021 Share Posted November 4, 2021 I'm pretty sure I just used one with mine, both times. I felt like two was too much with the spacer. Link to comment Share on other sites More sharing options...
Tehnation Posted November 4, 2021 Author Share Posted November 4, 2021 (edited) And the pump didnt fix the problem...... same thing, the saga continues. I'm going to look at the fpr and fpcm next. First I'm going to try one o ring, I primed it 1st time and it was at 30 psi, stalled and wouldn't start, then primed back to the 22 psi like before. Edited November 4, 2021 by Tehnation Link to comment Share on other sites More sharing options...
Tehnation Posted November 4, 2021 Author Share Posted November 4, 2021 My fuel pressure is to low...... can't be a leak I would smell gas, maybe clogged lines? Link to comment Share on other sites More sharing options...
whitexc Posted November 4, 2021 Share Posted November 4, 2021 And you put a new/different pump in during this saga? Sent from my SM-G996U using Tapatalk Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now