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Thread: Symptoms of fuel pump O-ring problem? Reply to Thread
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  Topic Review (Newest First)
07-21-2016 02:45 PM
Sherpaman Could someone post a link to the correct o-ring, I can not get a final answer that i feel good about ordering.




thanks so much


Sherpaman
05-01-2016 04:33 PM
johnny_k All is well with our Subaru, much thanks to you guys. Time to report back my findings and results, as a thank you and in case any other run into similar problems and dig up this thread.

Quote:
Originally Posted by 1 Lucky Texan View Post
yeah - might have wrinkled/doubled back on itself

um - did you SEE any problems with the original? cracked tabs or displaced/ruptured o-ring sticking out?
Bingo, that was the problem. And yes, maybe I forgot to mention, but the original had the typical popped/displaced o-ring and ruptured tab when I first removed the assembly.

Sure enough, I pulled the assembly (a third time!) and opened the cap, and the o-ring and slipped out of place because of how I had put it on. I placed it around the cup instead like is done in the video, put it all back together and that solved it - it started right up on the first try.

What surprised me the most is that the fellow who posted the video to youtube said that he had ran his car without an o-ring for a week and it worked fine, just needed a couple tries starting every time. I was surprised that just with a little kink in the o-ring ours would not start at all, but then again he had put in a brand new pump, where we were using two older pumps (the one we originally had on, with 150k on it, and the one from the junkyard with 100k on it).

The OB is back up and running very well, probably from the combo of the new fuel pump o-ring & cap, and a clean IAC valve and IAC body. The clean throttle body looks nice, but it's so big that I don't think cleaning a tiny bit of carbon off that really makes a big difference on performance. Thanks again all!
04-23-2016 05:12 PM
1 Lucky Texan yeah - might have wrinkled/doubled back on itself

um - did you SEE any problems with the original? cracked tabs or displaced/ruptured o-ring sticking out?
04-23-2016 02:07 PM
johnny_k
Quote:
Originally Posted by johnny_k View Post
That's what I thought - but it was still pumping. I disconnected the quick connect at the top of the fuel pump assembly and had a friend turn the key, got a squirt of fuel. Is it enough... I don't know. But seems like the reasonable amount for the ~2 seconds that it comes on when you turn the key on but don't start the car.

I switched out the pump anyways with the one I got from the junk yard (I know, a little risky). Still nothing!!

As far as the fuel pump the same thing is happening, I hear it getting power and coming on for the couple seconds, and I hear it running when we are trying to start the car. But pull the line coming into the fuel filter and try to to turn the key to 'on' repeatedly and no fuel comes out.

Could it be the relay? It sounds like the pump itself is working - if the relay was the culprit would the pump get any power at all.

I've replaced the cap and o-ring, but didn't take time to check over the rest of the plastic assembly to make sure nothing else is cracked that would cause the pump to lose pressure. Also, when replacing the pump I put the old filter back on the pump - it looked fine but I didn't try to blow through it to check the restriction.
Ok, I just re-watched the good video of this: https://www.youtube.com/watch?v=oXH1A9sHt6M

I noticed that he put the o-ring on the plastic piece itself, where as when I was doing it, it seemed like that would not work well to get the cap back on after, so I put it in the metal cap and threaded the cap with o-ring onto the plastic. Maybe I did this in the wrong order and it popped out of place.

Still, it seems like I should be getting some fuel pressure, at least a little lower, but not NONE. I'm just so hesitant to go and pull the fuel pump assembly a THIRD time and get nowhere...
04-23-2016 01:40 PM
johnny_k
Quote:
Originally Posted by 1 Lucky Texan View Post
weird - I guess a shaft or impeller is broken?
That's what I thought - but it was still pumping. I disconnected the quick connect at the top of the fuel pump assembly and had a friend turn the key, got a squirt of fuel. Is it enough... I don't know. But seems like the reasonable amount for the ~2 seconds that it comes on when you turn the key on but don't start the car.

I switched out the pump anyways with the one I got from the junk yard (I know, a little risky). Still nothing!!

As far as the fuel pump the same thing is happening, I hear it getting power and coming on for the couple seconds, and I hear it running when we are trying to start the car. But pull the line coming into the fuel filter and try to to turn the key to 'on' repeatedly and no fuel comes out.

Could it be the relay? It sounds like the pump itself is working - if the relay was the culprit would the pump get any power at all.

I've replaced the cap and o-ring, but didn't take time to check over the rest of the plastic assembly to make sure nothing else is cracked that would cause the pump to lose pressure. Also, when replacing the pump I put the old filter back on the pump - it looked fine but I didn't try to blow through it to check the restriction.
04-23-2016 12:00 PM
1 Lucky Texan weird - I guess a shaft or impeller is broken?
04-23-2016 01:12 AM
johnny_k
Quote:
Originally Posted by 1 Lucky Texan View Post
not sure on the durometer of the 928 I used(it was sent to me by a forum member - long story) - I did lube it with a film of oil.
I was able to find some viton #928 in the 75 durometer. I had picked up a 90 durometer as well as I had found it first, but the 75 felt closer to the OEM o-ring. Glad I went with the softer one, as the cap was already tight and tough to get on without trying to compress a harder seal. I was able to find a cap at a junkyard - got the whole fuel pump assembly as backup, good thing too as it looks like I might need it.

I got the assembly with new seal and cap in and back together, turned the key at least 5 times and tried to start it a few times, nothing. I can hear the fuel pump cycling on, but now I'm thinking maybe it has failed and the motor isn't actually turning the pump. I pulled out the supply hose to the fuel filter and had my wife turn the key a few times - not a drop.

Should I go straight to replacing the fuel pump with the spare pump I have off the assembly? (can't use the entire assembly, as the quick connects are broken) Or would it be wise to check anything else first? I can't really see there being a problem with the hoses, but should I maybe disconnect one of the hoses at the pump and see if I'm getting any pressure there? There are two quick connects and one clamped hose leaving the pump assembly, I don't know which one is the pumped line.

On a side note, Murphy's law, I had JUST filled the gas tank. Where the pump sits must be slightly lower than the tank itself, as at least a gallon of gas slowly overfilled and poured out. For anybody doing this in the future that has a full gas tank. you will save yourself more time and hassle in cleanup if you can siphon at least 2-3 gallons off first!
04-22-2016 02:24 PM
1 Lucky Texan not sure on the durometer of the 928 I used(it was sent to me by a forum member - long story) - I did lube it with a film of oil.
04-22-2016 02:14 PM
johnny_k From your brilliant investigation on page 2 of the thread:

Quote:
Originally Posted by Oo-v-oO View Post
Amazon currently has a 12-pack of 75 durometer Viton -928 O-rings listed for $12 or a 5-pack of 70 durometer nitrile (Buna) listed for a buck. They also list EPDM O-rings in that size, don't use them as EPDM is NOT compatible with gas!
And yes, this entire thread has been HUGELY helpful! Thanks to Oo-v-oO and Texan especially so far.

I've only gotten to page 4 of this thread, so apologies if this has already been answered:

You mentioned 75 durometer viton (fluorocarbon o-rings) or 70-durometer nitrile (Buna) o-rings - is this hardness critical? So far, I've only found one store locally that carries the same Viton 928 o-ring in stock, but only in a 90 durometer. Will the extra hardness make it that much more difficult to put the cap back on, and maybe more likely to crack/break the tabs if they haven't already been jeopardized?

I think they also said they had a 90 durometer nitrile o-ring, is one of those better than the other in a fuel environment?

I was hoping to be able to get the car at least up and running this weekend (using hose clamps if I have to depending on the state of the cap, which I have not seen yet. The Acklands Grainger stores in Canada do not carry the Viton o-rings even though their US branches do (classic problem in Canada).
04-17-2016 12:39 PM
Tall Bald and Ugly
Hah!

You folks were absolutely CORRECT! Two of the three tabs on the fuel pump are cracked and the o-ring is squeezed out on one side. I'm going to try the jury rigged hose clamp fix and see if that will get it going until I can arrange something more permanent.
Again, thank you, thank you, THANK YOU! If I still had hair on my head, I'd have been ripping it out by now, so thanks for this. I will get back to you on how it works and with pictures to boot.
peace
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