Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Severe engine stuttering

Well, it was a nice try. Stuttering came back along with the Check Engine light, then the light went out, stuttering stopped then the light lit up and stuttering returned.

When my TPS went bad I found I could alleviate the symptoms for a while by 'exercising' the throttle pedal 10 times before starting the engine. Theory is that this cleaned up the sensor potentiometer a bit, much like fixing a scratchy volume knob on a transistor radio. It usually gave me an hour of so of stutter-free running before I had to repeat the procedure.

JMD asked about fuel pump type - did you replace previous one with an MMC one or a Walbro?
If standard MMC then suggest try changing to a Walbro to see if it cures the issue - you might get 58 psi at idle but under load it may not cope and fuel pumps don't always fail straightway, they can take 100's of miles to finally fail completely as your first pump did.

I did not replace the fuel pump with the stock Morgan unit. The fuel pump, at a quick guess, is not the culprit. I made sure, at the time, that the unit going in was able to handle the occasional ethanol without self destructing. I do feel that the Throttle Position Sensor may be the culprit.

When the engine was running without the Check Engine light it was smooth and strong all the way up the range. It idled smoothly as well.

This beastie has over 55,000 miles on it and moving parts have been failing since the beginning.

I have an old Windows laptop that never connects to the internet, still thinks it's 2009 and is only used for Protune 2. I am sure you could get something similar for a few $$$. It would save you a lot of time and money with diagnosis.

If you have a fault code P0122 "Throttle Position Sensor low/short circuit" that will confirm the TPS as the problem. You can set the new one up easily and accurately using the Protune instrument read out for throttle position. Cheap(er) TPS can be bought via AliExpress, info on Alternative Parts List.

Back to basics. It was. found that the spark plug leads had corroded so much that they were shorting out and causing all kinds of electrical mayhem. New leads and plugs and the stuttering stopped.

Good to hear you are sorted!