I am stumped, my 1986 240 will start and idle OK, as soon as you give it gas the engine shuts down. I have replaced the in tank fuel pump, fuel filter with no improvement. Initial checks of the fuel pressure regulator looks good, amm seems ok. If you gently apply the throttle the engine will rev up OK, but normal appication of throttle kills the engine. All vacumn lines check good, Could this be an ignition issue. Any suggestions on where to troubleshoot next or hint at what I am dealing with would be greatly appreciated

Mystery solved, turns out it was a bad AMM, replaced the unit and problem went away thanks for the help

Do the AMM checks, then check out the vacuum line from the intake manifold to the ICM.

That line is easy to find on the passenger side. It is white nylon (I think) and connects to a diaphragm on the ignition contrul module (ICM).

On its other end, it comes up between #1 and #2 intake manifold rails. There is goes into a rubber 90-degree elbow that fits onto the manifold.

If that hose is off or open, the IGM doesn't see the drop in manifold vaccuum when the throttle is opens, so it doesn't advance the spark timing - and you have to "sneak up" on higher revs. Also seems to have no power.

Also check the accordian air intake hose. They are prone to getting holes on the bottom side - hard to see so you might need to feel under there or use a mirror and flashlight. A new one is around $20, a good DIY job.

Good Luck,

Bob

:>)

It could be a bad AMM or the connector to the AMM needs cleaning and re-connection. I've had both of these give the symptoms you describe. Try disconnecting the AMM (engine OFF) then start the engine. If it has the same symptoms, the AMM or its connector are probably the problem.

My daughter's '86 would idle but not accelerate. I pulled off the AMM connector afew times then made sure it was fully seated. The problem went away.

If you can "sneak" up to a higher rpm without a problem, could there be a loose ground which pulls away when the engine moves under torque?

Klaus
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98 V70Rawd(101Kmi), 95 854T(85K mi), 75 164E(173K mi)