73 Series III lurching...need advice

[ianhunt]

Hey folks-

Have had the truck for about a year now. Love it, except can not figure out why every now and then and more frequently now, the truck loses power when giving it gas and then starts lurching. When I let off gas for a few seconds it recovers and goes back to normal. A month or so ago, it stalled and wouldn't start and fortunately was right across the street from a European mechanic. They checked it out and came to conclusion that fuel pump needed replacing. Brought next day to trusted Rover mechanic and had him replace fuel pump. Still lurching. Carb was worked on a few months ago when I first complained about the lurch but to no avail.

Has anyone had this problem? Any ideas?

Any help is very much appreciated. I am stumped and worry about breaking down when I am running around town.

Thanks!

Ian

[taffhill]

I had a problem like this once, I checked all the usual suspects, filters etc. turned out to be a bad lead ....


just a suggestion and 2c

Mick

[CRiordan01]

Had an issue like this last year; if I remember correctly mine was related to the distributor connections.

[albersj51]

Fuel pick up getting blocked with debris from the tank?

[busboy]

Fuel pick up getting blocked with debris from the tank?

That is a possibility and the next time it won't start squirt some gas down the carb to see if it is fuel related. As you have changed the fuel pump already double check the fuel supply line from the tank at the pump to make sure it's really tight. It doesn't have to leak to let air into the system. Also check the complete line to see if it has rubbed through anywhere and letting air in occasionally. What brand of carb is it?

[chilidavid]

The word "lurching"rings a bell. I drove with my original Zenith for years, but was never happy that it ran rich (black but dry plugs) so I bought a reproduction Zenith from our host, just to try it out. Discovered that the new Zenith runs lean! It produces white plugs: and, when cold, my 2.25 engine seems a bit starved for gas, and starts lurching (mildly, but yes, lurching!). I now drive with a clothes pin attached just under the choke knob, and the lurching stopped. When cold, I simply pull out the choke knob a tad more, and she purrs like a kitten! Love my new Zenith. It just required a little training. No more lurching. (Note: I had already cleaned the tank, added new fuel lines, new fuel pump, and a new in-line fuel filter too, previous to the lurching behavior.)

[willincalgary]

As other people have mentioned it sounds like a fuel issue. I would check to see whether the needle valve in the carb is sticking closed or somehow obstructed. I had the exact sypmptoms you're suffering from. Does it only lurch under moderate to hard acceleration? After a particularly bad lurch-fest one day I disconnected the fuel line at the carb and pulled the top of the carburetor body off to find a very low fuel level in the float bowl (read this almost empty). I suspect the needle valve was sticking and only partially opening. As long as I didn't give'r there was enough fuel. When I stomped on the gas (drag racing with the local street racers) the truck ran into fuel starvation issues.

[jonnyc]

I had similar issues years ago with 2 or 3 Zeniths I worked with. A Rochester solved the problem.