Wet hole is a bolt or stud that goes into a threaded hole that penetrates into a coolant passage. So in order to seal the coolant some type of silicone is required. The sealant impedes the metal to metal connection and can be the source of a faulty ground.
As for air (aeration) of the fuel- you should replace the 1/4” diameter ip (injection pump) return hose. It comes out the front top of the ip, is like an upside down “U” shape and is around 5” long. Many of us used the clear hose available at any hardware store sold by the foot. It isn’t really rated as fuel line and needs to be replaced every 3-5 years based on your environment. The better choice is the clear fuel line from fuelline.com. It is rated for 25psi, and can handle any fuel including nitromethane and any alcohols.
With the engine running or attempting to run you simply watch for fuel flow. Any bubbles, or contamination is a sign to repair that problem BEFORE any others diagnosing or issue.
It is a simple job, takes longer to buy the hose than install it and is invaluable long term.
Install it and replace with more clear when needed from it getting hard where it may crack. Never run the black hose again.
The other thing that is a wise investment is something many people (myself included) believe should have been stock:
A tapping port (T fitting) made of metal so you can add a fuel pressure gauge AT THE IP INLET. Many many ip that were good have been misdiagnosed and replaced to only have the same issues- later to find deteriorating fuel lines or weak lift pump.
This is the only place I know of selling the correct fitting and advertising it for the ds4 ip. You could search it out yourself and save a few bucks- but not sure the savings is worth the time.
A fuel pressure gauge is essential to monitoring the health of your fuel delivery system. Mod Mafia makes it easy to add this important gauge to your Hummer / H1…
modmafia.com
Mount the pressure gauge where you see it when driving.
Stanandyne recommends 8-14 psi. Anything below 5 isn’t healthy and getting to zero or negative pressure is massively damaging to the ip. The price of the gauge is basically an insurance policy to save the life of the ip.
I tend to overdo things and am adding a second sensor that will be before the filter so I can see by comparison when the filter needs replacement. I will only use one gauge and have the two wires go to a momentary switch so I can read the pre filter side- then it will default to ip pressure. I used to always run a mechanical gauge in the cab- but simple never considered the fire potential. That was removed and won’t be reinstalled.