12ht high idle issue (1 Viewer)

[troopie]

I have this weird high idle on my freshly rebuild 12ht. Even when the throttle cable is disconnected and the high idle actuator is not hooked up to a vacuum source it runs at around 1500 rpm.
I already had this injection pump on my old 12ht (which broke the crank amongst other things....) and it worked fine. It was rebuild and calibrated a few years ago.
I triple checked the timing already.
Also the throttle linkage on the pump doesn't stick.

I really don't know where to start looking tot fix this.

Any help is appriciated

Mark

 

[chappohj47]

Get the motor up to operating temp and set the idle with the idle screw mine was set to idle with the hand throttle so I set it with the screw to 650rpm but most of the time it idles at 1000rpm some sort of auto idle kicks in

 

[chappohj47]

The idle set screw is the one closest to the block undo the lock nut on the firewall side and use a screw driver to turn it in or out will change the idle and set it to what you want or factory spec

 

[troopie]

Unfortunately it's neither of those.
It seems something inside the pump keeps the idle up. I can't even force the throttle lever down to get the idle lower.
I'm stumped...

 

[duncanrm]

Diaphragm ruptured?

 

[troopie]

The boost compensator compensates just fine. And there is no diaphragm like there is in a 2H pump... But i just found out that the new block is cracked big time. So the injection pump is now the least of my problems....