Change the oil Pump 1999 Chevrolet Express 3500 Van 5.7L 350Cu. In.

2000 Chevrolet Express Cargo fuel pump relay location Bing images

if doesn't engage because is out of freon or low pressure switch is not working or disconnected other then that clutch coil is not good or is disconnected

Is the engine light on? and what are the codes? I think its to do with the MAF mass air flow sensor.

Recommend investing in a Haynes manual for your van:
Chevrolet Express manual

that's internal engine repair so if you are not a mechanic you probably want to take this to a professional.

Probably a 3 out of 5 on my diy difficulty scale, here goes: 1 remove negative battery cable 2 raise and support the van on jack stands 3 remove the motor mount bolts from both sides( do not worry the engine will not fall on you) 4 remove the oil pan retaining bolts 5 unplug oil level sensor if equipped 6 bump oil pan with a RUBBER mallet to break the gasket seal 7 remove oil pan, you might have to raise the engine with a jack placed under the front pulley, use a block of wood to avoid marring the pulley, and raise the engine just enough to allow the oil pan to slip out. 8 remove the oil pump retaining bolt and allow the pump to come straight down. 9 you will have to re use the intermediate shaft, the collar that holds it on will most likely break when you try to remove it, you can get a new one, it will probably come with the new oil pump. You can reuse the oil pump pickup tube, but it is cheap insurance to replace it. reassemble in reverse order, pay attention to the oil pan gasket, be careful and get the corners in correctly, extra time spent here will prevent a leak later.

Illustration 7-4 http://www.daycoproducts.com/daycoweb.nsf/Serp%20Rout%20Guide%20Illus.pdf

if ur replacing it remove front grill disconnect both lines and carefully remove retaining clips from radiator if replacement is original eguipt mount & reconnect --if its a universal follow instructions usually cut off fittings and use clamps and hose to hook up

hi i havw a 3500g 1998 vortec we have no constant spark we need to find a wiring diagram whats the best sie to use not sure if some thing is wrong with the plug to the coil?

454 with ac and a.i.r.