To the Tucker wizards: Why 2 fuel pumps?

Why does my 1984, 1344 Tucker with 318, have an electric fuel pump, on the frame, connected with a canister suction filter, then connected to the manual fuel pump on the engine? When I used to mechanic for Dodge back in the 70's, one of the best engines they ever had was the 318. The only problem we ever had was someone would put an electric fuel pump on them, they either quit on the side of the road or pumped the crank case full of gas. There's a switch on the dash that shuts the electric pump off, can the manual pump suck thru the electric? What's the point of this electric pump at all? I bought this Tucker from Sno Trans last February, why does it not have a vented fuel cap? Before I went to start it this fall I open the fuel tank cap, it still had vacuum on it from last spring! The 318 does burn alot of fuel, heck of a strain on fuel pumps and tanks with not having a vented cap. Thoughts?

although not tucker specific, I have been known to add an electric fuel pump to seasonally used equipment.


Strange about the vacuum. My international experience (scouts mostly) had some strange fuel venting, I was told the closed venting system was to remain intact upon roll over. Nonvented cap. only way it got air was from the air cleaner via a charcoal filter. the filter housing was always under slight vacuum.

Mike

I spoke with one of my buddies, he told me the the old swather on the farm had a sealed fuel system as well for on the hills so the fuel didn't run out. He also said that the swather would not run climbing hills once the fuel tank got below half a tank, because the manual pump couldn't suck the fuel once gravity got to much for it. Once they put an electric pump on it, or kept the fuel tank full, it would climb regardless of the amount of fuel or the steepness of the hill. He also said that as long as the electric pump is an impeller type you should be able to shut it off & the manual will suck thru it on leveler ground. Thoughts?

I have no special knowledge, I'm just speculating...

Tuckers are used at more extreme angles both in terms of pitch and roll than typical automotive applications. I suspect the auxiliary fuel pump is to provide fuel under positive pressure to the mechanical pump. That way the mechanical pump doesn't have to overcome the associated gravitational forces under more extreme angles.

As far as the fuel cap, I would not assume the machine left the factory with that cap. I've seen the results of many "mechanical morons" attempts to maintain/repair a Tucker. Their motto seems to be "Why use the right part if a wrong one will fit?"

In my experience unvented caps are associated with the emissions control systems and the charcoal canister. Perhaps a previous owner lost the original cap and had one of the wrong type sitting around?

here's what the scoop may be the electric fuel pump may be an addition some one put on to overcome a vapor lock condition, also I have run into some instances where the mechanical fuel pump sits too far from the tank to be efficient, I don't think this would be the problem with a tucker. as for vacuum in the tank I would guess you have a closed system required to meet emission standards of the day. remember that is about the time frame we started to put an end to allowing hydrocarbons to escape in to the atmosphere.

I have run electric assist pumps on my equipment and hot rods for 40 years and never had a problem. I always put the electric pump to the rear close to the fuel tank. The thing you have to watch out for is matching the electric pump pressure with the mechanical pump. the old equipment is about 1/2 to 1 pound of pressure. You have to be careful getting the right pump for the job. Hope this helps. Clair

My 85 1344 has the same thing. I was thinking the electric to assist manual.

Could be to prime and start? My 75 1644 has not got an electric pump it looks like it may have had one at one time. her is a switch in the dash but no wire near where the pump would have mounted on the frame. There are two lines coming out of he tank on in the back for climbing and one in the front for decent.
the cat climbs great but some times stalls it I give it too much peddle coming off Idle on starting up a steep up hill it was over come when my leaning curve kicked in
my tank has a vent hose that runs up into the floor of the cab behind the back seat on the RH side and exits the cab on the right side just below the roof it has a 1 1/2 inch round stainless screen with a trim bezel. you could call tucker and ask Sterling about it.