Let's Talk About
Corvair FUEL PUMPS
IMPORTANT NOTE - As of 1-15-17 our reliable supplier of mechanical pumps has quit producing. Whether this is permanent or not is unknown at this time. Because I am a firm believer in mechanical pumps I am working on finding a replacement supplier. The comments below still hold true but I will try and keep you all updated as to our progress. Lon Wall
(Want a mechanical fuel pump that works great and can be depended on? Check out our special at the end of this article)
This is always a controversial subject amongst Corvair owners. But a great deal of the controversy is self inflicted. Mechanical or electric fuel pumps? Let's try and sort this out.
MECHANICAL FUEL PUMPS - These are the pumps that came standard with all Corvairs from the factory. The mechanical pump is a simple diaphragm type that is operated by a push rod which rides on an eccentric on the crankshaft. The pump develops suction which draws gas from the fuel tank and distributes it to the carburetors.
It would be simple to say that all mechanical Corvair pumps are the same - but alas, that is not the case. The original 1960 models had a pump that appears to be the same but has a longer rod exiting the bottom of the pump. In turn a shorter pump pushrod was obviously used. This design was carried over into 1961 models for an uncertain period of time. This is why if you own a 1960 or 1961 you should always measure the overall length of your pushrod before you replace the pump.
In that same vein I would highly suggest that if you find you have one of these earlier pumps you should convert it to the 62-69 type. Why? because it's easy and cheap to do and there is never a question in the future as to which pump you're using. If you should be unlucky enough to find an NOS earlier pump do not be tempted to use it!
These 60-61 pumps were last produced well over 30 years ago and that pump will be too old to reply on. To make the conversion simply get one of our part number U-481 pump pushrods.
Now let's go back 18 years ago to 1992. One of the largest makers of Corvair fuel pumps got a defective batch of diaphragms. THIS HAPPENED ONCE and only in 1992. But the repercussions have lasted ever since. The problem was corrected within a few months BUT because this manufacturer sold to many different retailers it made it appear that numerous manufacturers were putting defective pumps on the market. To make matters worse, some of those retailers moved very few Corvair pumps, so for years (even to the present) some "brands" (labels, really) still sell defective Corvair pumps - all ones made in that original batch 18 years ago.
Well, bad enough you say. Oh it can always get worse - and it did. Back in the early 90's a small parts vendor saw an opportunity. Because everyone at the time was in a virtual panic this vendor saw an opportunity to promote their fuel pumps. An abnormal amount of negative advertising and outright nonesense permeated the Corvair grapevine. The claim, of course, was that this vendors fuel pumps were perfect while everyone elses were bad. But there was an irony here.
As time went on it became more than apparent that the vendors fuel pumps were actually worse than everyone elses. Where their pumps came from were anyone's guess, but by hundreds of defective pumps and 3 different, but failing, revisions later the matter was dropped.
But that wasn't enough. During this timeframe numerous Corvair experts (some real some self-proclaimed) wrote articles that only clouded the issue even worse.
Some claimed that rebuild kits were the only answer. Ironic again, because the few remaining rebuild kits also suffered from the diaphragm problem, possibly because they had been the original supplier for this part from the beginning. Some claimed that certain visible features could warn you of doom. Visible reinforcement fibers in the diaphragm, the type of screws holding the pump body together, even the precise length of the lower diaphragm rod were all to be worshipped. While it's true that some of these identities sometimes had validity none of them were absolute. The issue of the diaphragm rod length was especially absurd.
It's true that the rod length has to fall within certain parameters, but the miniscule measuring of this rod was misleading overkill. The amount the rod protrudes from the pump casting can still vary up to at least 1/4 of an inch and still be within specs.
Take all of the above and horsewhip it to death from 1992 to the present and what can you expect? If you study the psychology of panics most of them look a lot like our fuel pump example. An issue can be twisted and confused so much for so long there is no way to untangle it.
Then we have to think that many people quit driving their Corvairs? No, a "white knight" came to some owners rescue. The electric fuel pump is used on nearly all modern cars. Electric pumps are generally reliable, and are readily available. So why isn't that the end of the story?
I have said since Day One that I would never talk a happy electric fuel pump owner out of their pump. That has never really been the issue. The issue are new Corvair owners and what they should feel compelled to do. I think it's irresponsible to tell a new owner that he has to get rid of a perfectly functioning mechanical pump and replace it with an electric.
Electric fuel pumps cost more than mechanical pumps, especially when set up safely, take a bit of work and knowledge to retrofit and have their own problems (as do all mechanical devices). Bottom line - they are unnecessary, but if you really WANT one (as opposed to being convinced that you MUST have one) then that's your decision.
But what if your mechanical pump has failed?
FIRST - Make sure it HAS failed. I believe that many fuel pump "failures" have nothing directly to do with the pump. The most common of these is when you develop an air leak in the incoming fuel line. Spots to look for trouble include the rubber connecting line just behind the firewall (old cracked hose or loose fittings are the culprit) and make sure the fittings where the incoming line connect to the pump are good. These air leaks can be transient or very specific and repeatable - all related to ambient temperature. If you think your fuel pump has quit pumping check these spots first.
And then there's leaks, both internal and external. Of course the biggest boogeyman is the internal leak that pumps gas into your crankcase causing everything from noisy lifters all the way to a trashed engine. This can be serious and I have seen it happen - with both mechanical AND electric fuel pumps - but it isn't so common that you have to spend every day immersed in paranoia about it.
External leaks can happen but they are usually the result of incorrect installation or other misuse of the pump OR you may have purchased one of the brands of pumps that never got sent back from the 1992 recall.
One important point about electric pumps is that if you chose to use one make sure to remember that the incoming line system was not designed to be pressurized.
MECHANICAL FUEL PUMPS - CALL pn U-480 As mentioned above I will be working on finding suitable replacements. Stay tuned....
New Fuel pump pushrod (does not include spring) - $ 12.50 U-481
My own fuel pumps leak stories Proper Fuel pump installation Electric fuel pump precautions.
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