74 sportster lower bypass cover

[jtjt]

I recently aquired a 1974 25hp evinrude with a toasted fuel pump, the engine has seen salt water and the screws holding the pump on were seized, unfortunatly while trying to remove them one of the mounting tabs snapped off the lower by-pass cover. I tried JB weld but its just not holding and upon trying to remove another lower cover from a parts motor that cover was seized in so hard it broke in half while trying to remove it, so i have a few questions if someone out there can help me?
1- Are all these lower covers generally stuck on this hard after this many years and if so is there a special tool or procedure i can do to safely remove it from the good motor so it doesent become a junker.
2- I ve pondered the idea of converting it to one of those three spiget style pumps being that one of them is a pulse line i could run a fitting from the lower cover and just mount the pump elsewhere, it could save me a major headache being that i have to buy a pump anyways. If anyone has played around with this idea aswell any help would be great. Thanks!

 

[1946Zephyr]

Re: 74 sportster lower bypass cover

I would just find a new bypass cover and keep it factory. There's lots of them available. In the Top Secret File, you will find a list of Salvage yards or, you can post a want ad on the AOMCI website. That should be the same bypass cover used on 18's, 20's and 25's from 1960 - 76. Just make sure the casting numbers match up.

 

[jtjt]

Re: 74 sportster lower bypass cover

My only fear being getting the old one out without damaging the block sealing surface or having half the cover stuck inside the block cause thats what happened when i tried to pull one off a parts motor, i mean it was seriously corroded in there and once it broke theres almost no way to get it out, im gonna try to rig up some kind of puller before i attempt it if i go that route. thx for the reply

 

[jtjt]

Re: 74 sportster fuel issues PLEASE HELP!

Re: 74 sportster fuel issues PLEASE HELP!

I put a new fuel pump on this motor and it still wont pull fuel, i ve covered all the basics like ignition and carb, i hooked the pulse line up to a spiget style with a hose instead of being bolted to the block so the seal is nice and tight, i ran the motor shortly with it disconnected from the block to see how strong the pulse was and its seemed weak, is this normal? The engine is running on a stand in a large garbage can and as long as the fuel tank is above the motor it runs fine cause its siphoning from the tank but as soon as you put it on the ground it runs its self dry. I ve tried several different styles of pumps and configurations and im definatly pulling my hair out, as long as this thing gets fuel it runs like a top, it really purrs, starts first pull, it pees water and never gets hot. Could the cylinder be dead or a reed gone bad? im all so using a mystery tank that i got hooked up, im a good auto mechanic but not super familliar with marine applications, my question being do certain motors require certain fuel pickups in the tank, the one im using is a three gallon fuel cell with a coupler like an air fitting but the pick up hose going into the tank is massive! i havent measured it but it must be over an inch. maybe the pump wont suck through it? Im going out on a limb here any HELP would be so apprieciated!

 

[AlTn]

Re: 74 sportster fuel issues PLEASE HELP!

Re: 74 sportster fuel issues PLEASE HELP!

suggest using a clear fuel line from the pump to the carb <vinyl hose works as a temporary one>..assuming you are using a j/e fuel line with the arrow on the primer bulb pointed towards the engine, you pump the bulb until you can see that the fuel is filling the carb bowl. The motor should start now and the fuel pump takes over. The primer bulb will become soft as it merely becomes part of the fuel line. On initial pumping of the primer bulb you may have to point it straight up before it'll pump properly. The fuel tank needs to be vented so no vaccumn is created in it. The pump has a gasket between it and the bypass cover.
With your gravity feed in place....run the hose from the pump to the carb into a clear container at about the same height as the the carb. Does it seem to be pumping enough fuel to keep the bowl full?..

 

[F_R]

Re: 74 sportster fuel issues PLEASE HELP!

Re: 74 sportster fuel issues PLEASE HELP!

There is a limit on how far the pump an lidt fuel, but a garbage can should be within that limit, albeit about max.

There are a few reasons for not lifting fuel.

1. Pump no good (you've pretty well covered that)
2. Pump mounted upside down
3. AIR LEAK anywhere between the pump and the level of the gas in the tank. Even a small air leak.
4. A high restriction anti-siphon valve in the tank outlet, or a restriction in the hose or primer fittings.
5. The size of the tank pickup has nothing to do with it. Well, maybe one that is too SMALL.
6. That motor will lift gas out of a bucket. Which brings up this: As a tempory test, just try that, eliminating the tank completely.
7. Of course, no pulse to the pump is a possibility. But if the motor runs on both cylinders, that isn't it. A very long pulse hose MIGHT e a problem.

It's interesting that you couldn't get that bypass cover off. In all my years, and thousands of motors, I've never seen that. Well if it was a complete junker retrieved off the sea floor, maybe.

 

[jtjt]

Re: 74 sportster fuel issues PLEASE HELP!

Re: 74 sportster fuel issues PLEASE HELP!

thanks for replying, im gonna check for air leaks today and do a compression test. im thinking the connection at the tank could be suspect of a leak its like an air fitting coupler and its old, my be an O ring is gone or something. Ya that lower cover i couldnt get off was on my parts motor and it was so stuck in there it actually snapped in half, it has become one with the motor, there is no f*ckin way it was coming off although the top cover popped off quite easily, so this experience made me really leary on taking the one off my good motor cause it would render any motor complete junk. both motors were run in tandem on saltwater for many years so there history is nearly identical. Which gets back to why i left the old cover on and converted the new pump to a spiget instead, the original pump was toast and one of the screws was really stuck, a very long battle ensued which broke one of the mounting tabs off and jb weld would not hold it together. This project has been a real pain in the ***. need more help!

 

[F_R]

Re: 74 sportster fuel issues PLEASE HELP!

Re: 74 sportster fuel issues PLEASE HELP!

It's still very odd that the bypass cover was stuck in there. Salt water can't get in there (past the gasket). The only thing supposed to be in the bypass chamber area is clean gas/fuel mix. Oh well, I believe you anyway.

 

[jtjt]

Re: 74 sportster fuel issues PLEASE HELP!

Re: 74 sportster fuel issues PLEASE HELP!

Well its good that you think that cause it gives me more confidence on changing out the one on my good motor, if its good! Reason i say this? Yes there was a leak at the tank, i cut the line before the fitting and got my dad to just stick the hose in the fuel and the bulb stayed nice and full, way better cause it kinda sucked before, any luck? No! compression test finally showed only 65 lbs in the cylinders and its a snap on gauge and i tested it on my air compressor and the gauges match perfectly. Probably why i thought the pulse was weak, im amazed it idled so well it had me fooled. im guessing at that compression its not producing enough vaccum/pressure to operate the pump efficiently. Im guessing your familliar with these engines and am really curious on throwing rings and bearings at it cause the engine really suites my application well, it also seems very easy to work on and parts are very cheap. i ve hand built a 350hp 350 and several dirt bike engines with good luck, whats your opinion?