Intermittent engine power loss

[Td5newbie]

THIS IS NOW RESOLVED - MORE NEW NEEDLE VALVES (this time Burlen), NEW FLOAT AND RE-SET FLOAT LEVELS


Help! Am meant to be taking Stag away to
Le Mans but an intermittent fault has reappeared after me thinking it had been fixed.

Stag starts and runs beautifully. Until it occasionally won't rev above 2500 or thereabouts- sounds rough when this happens with a very boomy "farty" exhaust note. Sounds and feels almost as though it is running on 4 cylinders . Car normally OK after restarting or sometimes the problem goes away whilst driving.

What has recently been replaced to cure it:
Carbs rebuilt with new needles and diaphragms- was found that one of the needles occasionally jammed before.
New coil
New dizzy cap
New rotor arm

This was done yesterday. No more problems for 90 mins afterwards. Have just gone for a drive today and 5 minutes in problem is back.


Car has a lumenition electronic ignition system and has run faultlessly for 3400 miles until now.

Could it be a dodgy fuel pump? Occasionally cutting out and then restarting ?

Any help appreciated...

[Arbman Al]

When were the plug leads last changed?

[Phil Stag]

Hi, could it be electrical. Would something as simple as a faulty plug or lead do that? Just a guess.
Good luck

[Td5newbie]

When were the plug leads last changed?

Last year when car was put back on the road but I'll try some new ones- will search the forum for recommendations.

[Td5newbie]

Have just checked- plug leads are the dark green ones from Robsport.

Noticed, when checking leads, dizzy cap is a loose fit. Also noticed that there is oil around top of coil. Coil is in usual place on back of engine. Presume oil means brand new coil is cooked?? Any views?

Many thanks
Andrew

[Arbman Al]

I got my last set of leads from ld parts.

Coil does sound suspect if oil leaking out.
Don't leave the ignition on for too long as it will heat up the coil.

[Td5newbie]

Have just checked the coil again and I can't see a ballast resistor. I have a mk1 car with a new loom made up last year so I'm pretty sure there is no ballast wire. If that is the case how has it cooked new coil in 2 hours when the old coil lasted 3400 miles ?

[Hettiherald]

Sounds like you have a ballast coil(6volt) and if no ballest resistor fitted, it will cook it as it is getting 12volts.
Dave

[Td5newbie]

Replaced with a lumenition mega spark with ballast resistor and new tighter fitting dizzy cap. Fired up fine and, I think, ran better but then had intermittent power loss hat cured itself. When I pulled over to stop later car wouldn't start but I noticed that I hadn't heard fuel pump. Tapped pump and it started up ok. Hopefully this is my issue. Will start a new thread on pump fitting.

[jbuckl]

Make sure the power to the luminition is a separate feed from the fuse box if possible.

[V Mad]

Ignition circuits were not fused originally - I guess the reason is that a blown fuse should not leave you suddenly stranded in the fast lane?

[Td5newbie]

Problem now solved- I think it all came down to duff needle valves which I replaced with Burlen ones, re-set float levels and replaced an old float whilst I was at it.
Would appear my other replacements were all a complete waste of time and money but at least I have a few "spares" now...coil, lumenition, leads, dizzy caps etc!!!!

[jbuckl]

Chris, you are correct....but one side of the fuse box is an un-fused supply, but you knew that.
Julian

Ignition circuits were not fused originally - I guess the reason is that a blown fuse should not leave you suddenly stranded in the fast lane?