M-920 won't run past low idle.

[Barron]

I maintain a nice 920 for a county, and I serviced the truck last summer, they don't drive it much, I went to start it and it would lope at about 450 RPM up to about 750 max no matter what the throttle position. I put on a new fuel filter, and ran a line from a bucket of fuel direct to the pump, and it still wont run right. It'll eventually die from the low idle speed. This truck has a nice big cam III, has low miles and used to run llike a scalded dog. Not sure what happened.

Any ideas?

 

[sandcobra164]

Did you run it's line to the bucket. I'll bet it's old, and the inner portion is collapsing under the suction. It might even look fine on the outside. Change the line from the IP to the fuel filter and post back.

 

[Barron]

I'm sorry, I didn't specify. I ran a new line from the bucket to the pump. Is there a screen at the inlet of the pump perhaps?

 

[cornrichard]

There is a screen in the top of the PT pump. I have seen a hex cap and a slotted cap. It is right on top of the pump near the fuel solenoid.

 

[Barron]

Thank's I'll try that. Definitely a restriction somewhere.

 

[MCTNKR]

You might want to confirm if the manual fuel shut off was pulled and is now not fully open. It needs to be all the way towards the firewall. If not fully to the rear, or if the internal o-ring is bad, you could get the same symptom.

 

[Barron]

Good idea, that'll give me something to work with.