Rough Running on an E-Type

The Problem

Michael Frank was experiencing rough running on his E-type. Basically, the car started running rough gradually and got to the point that he couldn't make it back up the hill although the car would seem to idle fine. He posted a message to this list and here are some of the suggestions that were offered as well as his final solution to the problem.

Many thanks to all who answered. The problem has now reached a point where the car isn't idling well. This is actually good, since I can work on it 'as it happens'. I was trying to figure out how to hook up all those meters and gauges and then drive up and down the hill!

Tonight I will begin by checking the electrical system again by the numbers, just to be sure. First, a new set of plugs. Next, I will dress the points. I will inspect all the wiring. I will also try new plug wires. I expect this will not be fruitful, so it's on to the fuel system. First thing I will do is temporarily disconnect the suppression condensor from the fuel pump. If this doesn't't do it, I will drain the tank and check the pickup (this will be the second time, but who knows?). Next, I will replace the fuel filter. If all this fails, it HAS to be the carbs, and they will have to wait until I get new gaskets.

I'll share one interesting thing I have discovered. I wanted to see if there was a high-resistance short to ground in the coil primary. So I blocked the points open and attached an ohmmeter to the positive side of the coil (let's not get into a discussion of coil polarity). When the ignition switch was 'on', the reading was infinity, ie, no short :-). What was odd is that with the key in the 'off' position, the meter read 3.5 ohms, ie, the coil was now shorted to ground. Not sure if this is to prevent theft, or an indication of a problem (ie, it's not a bug, its a feature)- any thoughts?

I have some great clues, thanks to all of you! Here were some of the responses, and my evaluation:

The Diagnosis

The Solution


I should have done this first. I know I should have, but didn't.

I put in a new set of plugs tonight, cranked the engine and.....nothing.

Bypassing a bunch of steps, I replaced the fuel filter. I turned the key without cranking, and listened to the click, click, click of the fuel pump, until it stopped. I then looked at the fuel bowl, it was full of .... air. This is actually OK, as it indicates that the fuel system has integrity, and there are no leaks. Those Grose Jets are working well. I then cranked and watched as the fuel bowl quickly filled up. This told me that the fuel system was basically OK.

Then I tried an old trick. No timing light. No Colortune. Just a spare spark plug. I plugged this into a cable, and set it down on a suitable surface. I then turned out the lights in the garage, and cranked the engine. It is amazing how clear the problem became at this point. The spark was very weak, and frequently non-existent. Bingo! Back to the distributor. I removed the points, dressed them down, washed them in alcohol.

Bill Lyon's Sixth Symphony! :-).

I think that the Mallory distributor has caught a virus from all of the Lucas components which surround it. Any thoughts on electronic conversion?

Thanks again to everyone who responded!

Mike Frank
1969 E-Type 2+2

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