1986 k2500 surging on grades?

[Deserthigh]

greetings truckers

 

I've got a 1986 k2500 long bed with a box stock 5.7, Carb emmissions intact (california emissions, truck lives in Oregon). turbo 3spd auto. 138k miles.

 

It's been running fine until today, it just started surging when going up grades, at 35 mph it surges like it was a fuel delivery problem, surges down then surges back up on the throttle. Like the bowl was going empty but then catching back up?

 

Does fine on the flat out under hard acceleration (or as good as it every was, which is slow at best).

 

no skipping, runs fine till you turn it up hill, does it in any position with the tranny, surges at 35mph regardless of gear.

 

Fuel filter has 10kmiles on it, however it may have been run down to near empty on the right side tank last week (foolishly loaned it to a friend)..coulda sucked in some dirt..

 

I'm thinking I'll fool around with the filter tomorrow then shoot some carb cleaner on everything under the breather...

 

What else should I look for?

 

thanks in advance

[Deserthigh]

greetings truckers

 

I've got a 1986 k2500 long bed with a box stock 5.7, Carb emmissions intact (california emissions, truck lives in Oregon). turbo 3spd auto. 138k miles.

 

It's been running fine until today, it just started surging when going up grades, at 35 mph it surges like it was a fuel delivery problem, surges down then surges back up on the throttle. Like the bowl was going empty but then catching back up?

 

Does fine on the flat out under hard acceleration (or as good as it every was, which is slow at best).

 

no skipping, runs fine till you turn it up hill, does it in any position with the tranny, surges at 35mph regardless of gear.

 

Fuel filter has 10kmiles on it, however it may have been run down to near empty on the right side tank last week (foolishly loaned it to a friend)..coulda sucked in some dirt..

 

I'm thinking I'll fool around with the filter tomorrow then shoot some carb cleaner on everything under the breather...

 

What else should I look for?

 

thanks in advance

 

 

My bad..I probably should have posted in the engine tech section...Still, any input would be appreciated..

 

JON

[Deserthigh]

greetings truckers

 

I've got a 1986 k2500 long bed with a box stock 5.7, Carb emmissions intact (california emissions, truck lives in Oregon). turbo 3spd auto. 138k miles.

 

It's been running fine until today, it just started surging when going up grades, at 35 mph it surges like it was a fuel delivery problem, surges down then surges back up on the throttle. Like the bowl was going empty but then catching back up?

 

Does fine on the flat out under hard acceleration (or as good as it every was, which is slow at best).

 

no skipping, runs fine till you turn it up hill, does it in any position with the tranny, surges at 35mph regardless of gear.

 

Fuel filter has 10kmiles on it, however it may have been run down to near empty on the right side tank last week (foolishly loaned it to a friend)..coulda sucked in some dirt..

 

I'm thinking I'll fool around with the filter tomorrow then shoot some carb cleaner on everything under the breather...

 

What else should I look for?

 

thanks in advance

 

 

My bad..I probably should have posted in the engine tech section...Still, any input would be appreciated..

 

JON

 

 

 

IT WAS THE FUEL FILTER.

 

filter was three years old, less then 9k miles on it. In that the surging was under load, (up hill) I figured it was fuel delivery related. I checked the intake manifold for leaks, (carb cleaner sprayed around it) then I went to the next easiest posible cause..the fuel filter..That was it.

 

JON