My '75 has factory fuel injection. All of the components as well as the wiring harness have recently been replaced. It starts up easily when cold and idles as it should. After driving for about 5 minutes, it starts to cut out and bucks badly. Once the engine is warmed up (oil at 180 degrees), it runs and idles fine. Thoughts?

Temp heat sensor?

Yes. I thought of that and will check that out. I replaced most of the components in the fuel injection but need to check that one out.

Do you have the knob on the top of the ECU?
If so, what is it's position right now, before you turn it?

No. Mine doesn't have that. I don't think the '75s have that.

What does it idle at when you first start it cold?
Or, does the AAR work properly?

Is the ambient air temp sensor working?
Is the CHT working properly?

Certainly sounds heat related, or it's too rich (which can be from a sensor)

Also, unplug the cold start injector, might be adding too much fuel...may also be stuck open so you may not fix it by unplugging it.....


Look at your plugs, look at your tailpipe...see if it is running rich

Sorry, I assumed ( because you did not say) you had djet.
I read in another thread that you have ljet...

So, with ljet, you may have air leak issues, so check all the vacuum lines, and the large rubber hose that goes to the AFM.

Also, verify your valves are not too tight.

Check injector seals to make sure they are installed correctly.

Basically, look for air leaks everywhere, that is why they stall.

In the future, it helps to state what fuel system you have, just makes the information you get much more on point.

Thanks. I will check for leaks. It doesn't "stall" as much as it cuts out.