Mechanical fuel pump

I believe mine is going out or has lost some psi. I'm concernd with weather or not I should replace it with a filter style or a non filter style. The fuel tank is original and prolly isn't the cleanest thing inside so I'm debating. Have any of you with an older cc switched to a filter less model and if you have how did it work out?

It looks like that would work perfect. Thanks!

I did this just today, I pulled the tank and tilted it to one end to suck out all the junk. It really wasn't as dirty as I thought it was going to be. Also I found a new mechanical fuel pump with the filter on it for $44 that I just installed this evening. It works great and my motor seems to idle a lot better now as well. Thanks for the info fellas!

Advanced auto parts! Napa Auto has them as well.

Pete,
    First off how's it going? I haven't been on here for awhile hopefully you remember me. To answer your question no it is not, reason being is because the carter pump I pulled off of it wasn't either! The new pump is a Airtex 4990 and is almost an exact replica from the carter it's just alittle taller.

Thanks for the info Joby! And yes I think you are correct!

Joby1969 wrote: arent the only difference on the pumps the little bypass nipple in case of diaphragm failure.

Well basically. A marine pump for sure has a seal on the diaphragm push rod in case the diaphragm ruptures. If not there the,overflow fuel will just fill up the crankcase and may also come out the the arm pivot rather than go up the sight tube. When I rebuilt my old '69 pump I added the overflow too, but it did have a seal too. Some pumps in the past had a dual diaphragm and a sight tube or a glass bowl between them to see the overflow if the main diaphragm went bad.

Tomj72mus wrote: Thanks for the info Joby! And yes I think you are correct!

He's not totally correct. Besides the nipple to connect the hose back up to the carb incase of a diaphragm leak. the true marine fuel pump is a double diaphragm.

BTW, just because the bad pump wasn't marine doesn't mean you have to put another non marine back on the engine. For a few more $$ than the $44, it sure would be safer!

8122pbrainard wrote: He's not totally correct. Besides the nipple to connect the hose back up to the carb incase of a diaphragm leak. the true marine fuel pump is a double diaphragm.

Not any more Pete, I believe in a Windsor powered boat the only true dual diaphragm pump had the fuel bowl on them. I think it has a diaphragm a spacer then another diaphragm. The glass bowl mounts into that spacer. If the bottom diaphragm leaks it fills the bowl,the second diaphragm keeps it from flowing into the engine or bilge. Since they went with the hose I have never seen 2 diaphragm pump. When I rebuilt my pump it had a seal on the diaphragm rod and one diaphragm,I added a fitting for the overflow when I found that it had the 2nd seal. I bought a new Carter marine pump from Skidim as a spare,it has the same upper housing as my original and one diaphragm.
New Carter-



Old Carter on HM-



If you look you can see just the one diaphragm on both pumps,it's the one under the series of screws,the other protruding one is a gasket

Here's a picture of an AC on the left and a Carter on the right.

im running the carter if i remember right, it didnt come with the nipple so i took the old nipple and used it in the new carb.I think the spot for nipple was already on the upper side of diaphragm. I have 4 daughters ranging from 5 -30, sometimes i forget and need a little reminder and thats why the woman is here. she keeps reminding me of what i have invested in toys.

Here's the link Keith. They need the numbers that are on the mounting flange. I don't think you can look it up yourself there seems to be alot of pages,might be easier to email or call them. At the time new screws for the pump halfs were not included in the kit but were available,they help make it look like new. Hope this helps.

Guys the bad news on Mechanical Fuel pumps is that all the major manufacturers quit making them due to very low volume sales. Carter and AC both quit manufacturing and farmed out the mechanicals I believe to Blackstone who makes them for Carter.
I think Airtex may still make some mechanicals and may even supply Carter with some of them. When Fuel Injection and electric pumps took over the market in the mid 1980's the volume of Mechanical pumps fell so low so fast that most manufacturers just exited the manufacturing and one or two now supply everybody.   There are some China manufactured pumps coming in also.
If I had a good old pump I would consider rebuilding the old one. Maybe some company still offers new diaphragms for them.
In the classic car world fuel pump issues are a problem, the original Carter pumps lasted years and years the replacements sometimes don't last long at all unfortunately.