[Rovernet] P5 problem persists

[Tom Rymes]

On 05/24/2015 1:07 PM, Peter King via Rovernet wrote:

> Sitting on the side of the road at the moment, waiting for the P5 to cool down enough to start again. Obviously, running problem persists. Checked timing and compression again. All good: compression 140, 141, 140, 120, 145, 140. New plugs today. Adjusted cold start lever to ensure it closed properly. Checked carburetor tune again. Start quickly, runs beautifully for 20 or so minutes then begins to sputter till it shuts down. Once it cools, all is good for another short trip.
> Now what?  Still fuel delivery?  Not enough pressure from the pump?

Peter,

Have you replaced the ignition rotor? If you haven't, start there, and 
use one of the red rotors sold by Jeff at Advanced Distributors ( 
http://www.advanceddistributors.com ). It may not solve your problem, 
but this is a common source of trouble due to MANY bad replacement parts 
manufactured over the years. If this isn't your problem, it might avert 
a future problem, and at worst you'll have a good spare for the boot.

Having said that, your first step really ought to be to diagnose your 
problem. First, figure out how to crank the engine from under the 
bonnet, and when it fails, check for spark (leave the ignition on):

1.) From the plugs - Remove a plug wire and plug from the engine. Then 
ground the plug against something and crank the engine. If you get a 
spark, then your problem is not in the ignition system. If you don't get 
a spark, then check it...
2.) From the Coil - If you have no spark at the plugs, disconnect the 
lead from the center of the dizzy cap and hold the metal contact near a 
ground (leave a gap about the size of the gap on the plugs). If you see 
a spark jumping the gap as you crank, then your problem lies between 
that wire and the plugs, leaving the cap, the rotor, the wires and the 
plugs. If not, then your problem is somewhere in the coil, the 
low-voltage ignition wiring, or the distributor itself.

When you have a problem like this the first step should be to eliminate 
areas of concern. Following this process should at least let you know if 
the fault lies in the ignition system or elsewhere.

Tom

PS: If you haven't had the distributor rebuilt and re-curved at some 
point, make plans to send it to Jeff at Advanced in the off-season. It 
will come back better-than-new. Many, many issues people have with their 
ignition systems can be solved by proper servicing of the distributor.