intermiten idle

[whitehorse]

Hi all have an issue with my 66 mustang about a month ago would start the car up as always first go and the car would idle nicely after driving around for about 20minutes and I come to a set of lights my car would randomly jolt like it has a voltage drop or fuel blockage doesn't die but feels like it might,  this is not always but only happens at operating temp and only when I come to a stop most times I have to put it in neutral to keep idle up.
By the way the car drives well I've replaced the fuel filter on Corby and one after the pump over the past 12months I changed the coil to a yellow top, plugs and leads had the carne cleaned out, new starter solenoid, solid state regulator.
I don't know what's causing this issue and love to drive the car just paranoid about coming to a stop.
Anyone have any thoughts.

[JT_1994]

If it's running points in the distributor, check them. Also check the spark plugs.

Mine were cr@p and the car would occasionally miss (and felt like it was jolting) when stationary, when it got really bad the motor would die and then immediately start running again, even though I didn't do anything to get it going again..
It didn't make sense at the time because it started off by just missing, then it started dying whilst I was driving and it became more and more inconsistent with when it was happening..

[whitehorse]

Points are new  and plugs are healthy

[barnett468]

what carb do you have?

have you tried adjusting the fuel mix screws?

remove the distributor vacuum hose while it is idling and see if the engine rpm reduces.

remove the pcv valve while it is idling and the idle will go up / plug it with your thumb and the idle will go down . see if the idle is slower with it plugged than it is with it stuck in the valve cover.

make sure the gap on the points is .016" - .018"

remove the rotor and grab the top of the dist shaft and try to wiggle t to see if it has any ply.

post results.

[whitehorse]

Interesting I've also just changed the pcv valve and grommet ill try what you mentioned on the weekend also my ditsy was reconditioned and curved at scorcher 2years ago ove also changed rotor, cap and leads.
Something I didn't mention earlier is I've gone from bp98 fuel to bp 95 surely it couldn't be that?

[barnett468]

Interesting I've also just changed the pcv valve and grommet ill try what you mentioned on the weekend also my ditsy was reconditioned and curved at scorcher 2years ago ove also changed rotor, cap and leads.
Something I didn't mention earlier is I've gone from bp98 fuel to bp 95 surely it couldn't be that?

no, the fuel wouldn't do that.

it doesn't matter who recurved it and half the time they are not ideal, you should still test it to see if its correct.

[Ray68]

Might not be your problem however I had the same problem and it took forever to find the cause. In then end it was a bad connection under the hood in the wiring harness for the neutral safety switch. At idle the connection would move making the car appear to miss,jolt and try to stall. Have had no problem since fixing the connection.

If your switch has been bypassed you'll have a piece of wire looped from one side of the connector to the other. If it is loose you'll have the same problem.

[GLENN 70]

Check the float levels .

[whitehorse]

So I finally got some time time to look into my idle issue and it seems that my crab is weeping fuel via the ventures hence why it drives well and but has an issue when I come to a stop, what could be causing this as I had my crab rebuilt 2 years ago.

[GLENN 70]

As I said the float level is to high . Why , could just need adjusting or the needle and seat is leaking causing the same problem . Just a little bit of crap in the needle and seat will hold it open and cause fuel to run into the carby . What type of carb is it ? .

[whitehorse]

2100

[whitehorse]

So I finally got some spare time to look at my above problem but  after checking and replacing fuel pump, blowing out fuel lines and sender replacing fuel filters, checking carburettor I found the issue was a faulty ignition coil ok when cold but after 20+ min of driving it was giving me an intermittent idle so I replaced my yellow top and all is good so far.
Thanks for all the feedback guys.