Odd engine activity

[dazzza]

Hi,
My '83 wagon has completed 300K+ kilometres from new, and apart from a wee bit of pinging, has not missed a beat.

PROBLEM: the motor starts up immediately; idles without a hiccup; BUT, after a few kilometres the engine starts jerking, sometimes quite vigourously (almost as though there is a fuel issue).
On one ocasion I travelled 41 kilometres without any issues, but on the return journey the problems begin; on average after 5 - 8km the issues start.

My mechanic has checked the fuel flow (pump working well); we have drained the fuel; replaced the fuel filter; we have checked and rechecked the timing; replaced spark plugs and leads; replaced the fuel cap ('ventilation'); changed the coil; (I do have some spare parts from an 84 model). oil change shows no water in the engine (I do have a small radiator leak, with some 'mousse' like slurry at the top???; the engine is not smoking.....
My mechanic, of long standing, also owns a Subaru.
I have not got enough hair to pull out any more, and have drawn a blank on the problem.
Would someone have any thoughts or solutions to the problem? Ta

[TOONGA]

Check the phenolic plate on the bottom of the carby, these have a knack of cracking and letting water seep into the intake manifold. I was just recently stumped by a vey similar problem and it wasn't until the plate fell apart in my hands, that I realised what the problem was

Then pressure test the system as it could be the intake gaskets leaking as well.

TOONGA

[steptoe]

Ooh, I wonder..... fusible/fuseable links just a bit iffy, corroding?? I have had this twice now with old subes around their 23rd birthday but whole thing eventually dies and cannot start it at all bar hotwiring. Maybe if you hook up a hotwire with a switch to enable when the problem occurs with the hot wire bypassing the ignition switch and fuse links ??

[steptoe]

Or...even though fuel flow has been checked....the first few months of ownership of my Brumby was wrought with havoc, saw me rebuild the carby after the usual leads, plugs, rotor, fuel filters (there is two on Brumby), witness a chang always in the cold of the night in summer causing me to have to drive home downhill way first rather than uphill, refuel gave new lease on life. It was only when I blew compressed air from rear fuel pump and filter back through tank of just the lines no components that a thoonk of rust crud build up blew into the near empty tank - problem resolved. been a good fix for a few others in here in recent years too!!

[Alex]

Ooh, I wonder..... fusible/fuseable links just a bit iffy, corroding?? I have had this twice now with old subes around their 23rd birthday but whole thing eventually dies and cannot start it at all bar hotwiring. Maybe if you hook up a hotwire with a switch to enable when the problem occurs with the hot wire bypassing the ignition switch and fuse links ??

YES. I had similar problems with my l-series once upon a time.

[El_Freddo]

I've had the fusible link issue, but it would die before I got home and I'm lucky I haven't fried the ECU or something important due to the lack of proper power supply in the system...

I've also hear the fuel line blow back has helped quite a few members on here.

Cheers

Bennie

[Smokey]

My mechanic has checked the fuel flow (pump working well)

I had a similar sounding problem with my fuel pump. It appeared to work well but I changed it anyway and the problem disappeared. So I either had a intermittent fuel pump issue or a blockage on one of the two pipes I replaced with the pump. Pump was from an older doner car.

Re mouse in the rad, leak down test by your mechanic may help to confirm that theory. Though form my recent issue w a blown HG, the car ran fine even with a moderately bad HG.