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Fuel pumps... WTH??? |
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CamJam 
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Joined: Jan/04/2014 Location: Arizona Status: Offline Points: 6553 |
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 Posted: Oct/09/2016 at 4:30pm |
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80+ mph today for a few miles and a couple full-throttle acceleration runs. Still no leaks! Keep in mind that this is a pump that leaked before and the only thing that has changed since then is the size of the vent holes. I did not replace or repair the oil seal. If this turns out to be the only thing that is causing these pumps to leak, I think it's very significant. It's a common problem, for SBC owners too. Why this would be a problem now and not back in the day is beyond me. Perhaps the size of the vent hole changed (these pumps all seem to made by one manufacturer now as stated earlier) or the diaphragm design changed resulting in more air displacement now.... I just don't know. I can see from photos of the rebuild kits that the diaphragm design has indeed changed from the original Carters. It does seem funny to me that the manufacturer would not have discovered such a simple fix themselves, which is why I'm reluctant to say that this is the cause. Also note that my pump is the current Airtex 905 (and equivalent pumps from Carter and Precision), which replaced the original Carter M-4656S used in our 1969 cars with electric wipers. I have no idea whether this fix would work with other pumps as well. I'll update this thread down the road if anything changes. |
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amxdreamer
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Joined: Jul/30/2008 Location: Vancouver, BC Status: Offline Points: 8511 |
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Posted: Oct/09/2016 at 6:29pm |
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Thanks for the updates Cam :)
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Tony
Vancouver, BC 1970 AMX 1972 Badassador AMO#10333 |
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CamJam
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Posted: Oct/09/2016 at 6:35pm |
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Took apart another of my four oil-spraying fuel pumps just now, and on this one the crimped oil seal had popped out of it's cavity, which is the other common problem with these junk pumps. It's still under warranty, so I'll put it back together and return it.
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Red20
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Joined: Jan/29/2013 Location: Oceanside CA Status: Offline Points: 1556 |
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Posted: Oct/10/2016 at 10:18am |
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Did you get the one I sent you yet? Is it what you were looking for?
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1969 Javelin SST "Screamin' Banana" - Totaled Feb 2018
1973 Hornet Sportabout X "yellajack" - 360/727/TracLoc DAILY DRIVER |
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CamJam
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Posted: Oct/10/2016 at 12:51pm |
Yes Josh, I did get it. It's not an original Carter, but a replacement Airtex from the 1980s. No worries... I can still rebuild it, and it was interesting to take it apart and see that Airtex was using the same crappy design even back then. |
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CamJam
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Posted: Oct/10/2016 at 7:19pm |
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After today's drive the pump was leaking oil again  . At least this time it didn't spray oil all over the front of the engine... I suppose because the larger vent holes decrease the pressure somewhat. So, I took the pump apart AGAIN with the idea of increasing the size of the vent holes a little more, only to find that the %$#^* oil seal had popped out. Comparing this pump to the Airtex pump from the 80s that Red20 sent me, I can see that the old pump has the oil seal shell "staked" in with a punch, while the new pump does not, so it depends only on a press fit to hold the seal in place. You can see the punch marks at about two and seven o-clock in the photo: Since the shaft moves up and down once with each revolution of the engine, this seems pretty poor, especially since the press fit is not very tight at all. So, I took the top half of the old pump (which includes the oil seal) and put it on the new pump. I just got back from a high-speed run with my hybrid pump and all is good again Other than the McRobb pump, I don't know of any other design that is still available for our '69s. My suggestion before installing one of these pumps is too take it apart and either stake or JB Weld the oil seal shell in place. JB Weld will withstand up to 500 degrees F and claims to be oil resistant, so it should be a good choice provided you get everything really clean with lacquer thinner first. Drilling the vent holes out to 1/8" or 9/64" is probably a good idea too. I still don't know if that is part of the problem or not, but it doesn't hurt, and a minimum it seems to keep the oil from spraying all over the engine bay if the oil seal does let go. In my experience the spray becomes a drip when the vent holes are a little larger. |
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CamJam
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Posted: Nov/17/2016 at 7:53am |
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Update: 5 weeks later and my hybrid pump is still working fine. As a reminder, it has the oil seal "staked" in place and the vent holes drilled out to 1/8". My guess is that JB Weld or PC7 would probably work to hold the seal in place too.
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CamJam
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Joined: Jan/04/2014 Location: Arizona Status: Offline Points: 6553 |
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Posted: Jan/17/2017 at 8:08am |
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Update: It's now a little more than three months after installing the modified fuel pump, and all is well!
Yes, the current aftermarket fuel pumps suck! Suggest you stake or glue in the oil seal if you're going to install one of these pumps. Increasing size of vent holes certainly doesn't hurt either. Edited by CamJam - Jan/18/2017 at 6:22am |
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mramc
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Posted: Jan/17/2017 at 4:52pm |
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I think it is not so much the fuel pumps sucks but that you have old pumps that have sat on the shelf for years on top of the crappy gas we have now days. The high alcohol content acts very like an acid. LRDaum
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LRDaum
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scott
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Joined: Jul/10/2007 Location: Wildwood Pa. Status: Offline Points: 3502 |
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Posted: Jan/17/2017 at 4:57pm |
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Thanks for posting an update Cam. I need to get a new pump & was wondering if your fix on a parts store pump had worked.
Do you have a part # on the pump you have been using?? |
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Red20 wrote: