Engine pick up/Rough Running

[Pete1965]

Hi There,
Bit of help please people if you would be so kind.

73 plus 2, Running on Webers with Lumination elec/ign. I have a recurring problem, car starts and runs beautifully for 30 mins/40 mins. Then starts to splutter, and fail to pick up, gets progressively worse then virtually undriveable and have to stop. Pull over for 10 - 15 mins, car starts and runs fine, for further 5-10 mins then problem reoccurs.
Mechanic, initially thought problem had been solved by cleaning out tank, which had bits of silicon floating around in it from a previous bodge he said and bit of snail shell wedged in banjo bolt!

Now thinks it may be a failing fuel pump (standard mechanical) that is giving out after the car has been running a while. Was thinking of installing Facet Silver top fuel pump, but just have a feeling it may be something else!

Any thoughts?

[collins_dan]

Sounds like the coil might be overheating. I replaced my Lumination with Petronix a while ago because it didn't get along with my coil or tach. Check what kind of coil you have and post here. Others may be able to tell you if that is the problem. Good Luck, Dan

[mbell]

Sounds like the coil might be overheating.

I second that, quite a few have posted with similar problems.

[Quart Meg Miles]

I had that problem and it was the alcohol in the petrol causing vapourisation leaving the fuel pump dry. If you peer closely at the pump bowl next time you conk out and find it is empty then that is your problem too. If so fit a Facet in the boot and the problem will go away but fit a regulator after the mechanical pump. I can PM you photos if you need them though mine is not a +2.

My engine pump had perfect valves and the car only started having the problem a few years ago though not as severely as you describe unless it was very hot weather. I don't have electronic ignition.

[Sea Ranch]

Another vote for coil (and easy to test: find another running twin cam and borrow coil for a couple hours. Even better than buying a new one to test, cause the new one might not be very compatible, and they're not returnable

And the stock fuel pump is easy to check levels in.

Good luck, let us know how it turns out

Randy

[mbell]

Also worth checking coil voltage (9/12) and if you have a ballast resistor fitted. Either resistor fasten to the coil which I think is standard or restive wire in the wiring.

My 73 should have the balast resistor but it's been removed and the two coil supply lines (run and start connections) joined together, therefore I run a 12v coil.

If you have a 9v coil running on 12v it would overheat....

[Chancer]

Spot on!

Overheats after 10-15 minutes, runs agan when cool but re-heats even quicker.

The same can be said for a Lumenition power module made circa 1991 due to non existant heat sinking of the darlington driver, you cant verify this as the electronics are potted, when the manufacture was subbed out the supplier stuck the component down with double sided tape instead of a mechanical fixing with heat sink compound.

Same symptoms but more likely to play up around 2-3K revs. Unlikely to have lasted all these years but the car could have been off the road or new old stock used.

[alan.barker]

+1 for Coil.
If you do fit an electric pump i have just fitted a Huco low pressure next to petrol tank 133000 (on my tvr 3000m). Much quieter than facet and you can orientate the inlet and outlet.
Alan

[ericbushby]

Pete.
Mine did that!
It would leave home running well and after 30 to 40 minutes start to misfire and then stop and refuse to start again.
After being recovered and back home it would start instantly.
Turned out to be the rotor arm short circuiting to the shaft when it became hot.
Under a lens I could just see a tiny bubble on the plastic inside.
Eric in Burnley
1967 S3SE DHC

[Pete1965]

Thanks for all the replies guys, I will work through the list, starting with the coil as that seems to the popular choice! Move onto the fuel pump next and take it from there. I'll report back in a couple of weeks when I've had a bit of time on it. Many thanks all!