Fuel and AC problems

[emil49]

We have two 2001 duramax trucks 200000 to 250000 miles and 2003 with 110000. Trucks are general farm use, plus they pull silage wagons loaded (30000 to 38000#). The trucks don't run hot, but at idle in the field the AC gets really weak or not working. If you idle up to 1200 rpm the AC works pretty good, going down the road it is cold! At $500 to $600 I'm not wild about replacing a fan clutch to see if it would improve the issue. Trucks get thoroughly washed and it doesn't help the AC enough. GM dealer has seen similar problems with work trucks. I'm considering removing stock fan clutch, fan and top radiator shroud and installing electric fans from a junk yard vehicle so I get more air movement at idle. Comments?
One 2001 and the 2003 have issues with getting air in the fuel system or dropping the fuel. It started occasionally on both trucks. the 2003 got so bad that we couldn't hardly get it primed. GM dealer said it could be a bad primer(problem). So we bought a new primer, can prime now but still drops fuel, gets air in system in as little as 20 minutes, and then you will have to prime it at least twice to get to run longer than 15 seconds. Lift pumps? I read about Kennedy. Will a lift pump help when air is getting in the system? Will it help prolong the life of a weak injection pump? As bad as the 2003 is I think we need to find the leak. I read about pressurizing the fuel tank for leak detection or should I let the GM dealer fix? Comments?
Thanks
emil49

[Kennedy]

On the fan clutch how does $175 suit you?

Hauling silage puts you in a lot of dirty, chaff infested air. I know you said the trucks get washed, but have the radiators actually been removed to have the air side cleaned? I suspect lots of tumbleweeds, birdfeathers husks, etc blocking air flow.

A Lift pump is a must have in my opinion. Keep the system fuel of fuel and not air. It is much more difficult to seal against air than a liquid. With a lift pump if there is a leak it will weep and will definitely keep the air out.

[emil49]

The GM part I was told was $500. Where is the $175 one? Does it lock up at low rpm's. We removed the grill not the radiator and washed with Hi pressure washer till water from radiator was clean. With trouble light it looks clean through and through. Where is lift pump installed? Does it come with instructions? Does it show or tell where to get juice for on off operation with the ignition? What about the electric fans?
Thanks
emil49

[Kennedy]

We offer a replacement clutch that has done quite well on our web store.

In order to get the cooling stack clean you need to remove the radiator. The front of the radiator is covered by the intercooler. If any item in the cooling stack gets plugged the air flow is reduced.

Detailed lift pump installation instructions here:

http://www.kennedydiesel.com/docs/BasicLiftPumpInstallation.pdf

I have a control harness that is very simple to install and contains detailed instructions.