Installed water pump on my Volvo 86 740 ZLE and the Volvo engine keeps shutting off. What could be wrong?

Most cars you can do without lifting engine make sure don't do anything wrong for nothing.

Replace your water pump.

fans are designed to run on after you shut engine down as engine temperature rise after switching off . running hot could be caused by the top hose having gone soft when you rev the engine the water pump sucks the hose flat stopping the coolant flow or the radiator is blocked and need flushing out

ok there are two o rings in the water pump one keeps the oil from the timing chain side to come in the water and also keep the water/coolant separate from the oil side the second one keeps from coming out of the engine. i am sure the first o ring i talked about is pinched or damages or is not installed when the water pump was installed.

It has been many years, but I am pretty sure that there is not much that you have to take off. Just the fan and maybe the top plastic timing belt cover.
Be sure to take steel wool and smooth the tip of the water pipe that runs along the exhaust side of the engine block so it gets a smooth seal where it presses in to the new water pump. Also smooth the bottom of the head where the water pump fits up beneath it.
The tough part is keeping the O-ring on top of the water pump from leaking because there is no bolt that holds that seam tight together. What you do is - you snug the bolts that hold on the water pump, then take a lever and pry upward on the water pump to squeeze that O-ring while tightening the bolts the rest of the way.

if the thermostat is broken the fan should keep turning. Check the fan if it spins once you get the car warmed. Otherwise it could be a blown fuse or relay for the fan or the fan itself may be bad. Check the radiator hoses and the radiator cap for loose or worn parts. Steam may escape there decreasing the water in the cooling system. The problem could be also be with the water pump. If you are to replace the timing belt have the water pump replaced since you will spend the same effort getting to both the timing belt and water pump. It is recommended that this be done by a specialist to avoid damaging the engine.

Your Volvo does not have have a problem at all. The feature is what is known as a 'turbo timer' and is an important part of most turbocharged vehicles such as yours.

Your volvo is powered by a 5 cyclinder 2.4 liter engine that is turbocharged. Which means the engine works on the principle of 'forced induction' whcih helps it make more power.

A turbo like yours has a small impellor placed in the early section of the exhaust which is then spun up by heated and expanding exhaust vapors. this power is then transferred back to a 'charger or pump that actually forces additional air into the engine resulting in the ability to burn a more powerful mixture of air to fuel. Unlike your engine which even under very aggressive driving will only sustain forces at most approachign 9 thousand rpm, a turbo charger often spins with speeds in the tens or even hundreds of thousands of revolutions per minute. because of this they depend on a steady stream of engine oil to both lubricate and saturate the very rapidly spinning parts to keep them cool.

when the engine is suddenly shut off after a long or spirited drive the oil pump also stops, this could result in overheating and damage to the turbo.

As a result of this, Volvo was one of the fisrt companies to install a 'turbo timer' mechanism in its T models which as you noticed will continue to operate the fan for a pre calculated amount of time after you shut the car off in order to properly cool down the turbo.

Again your car has no problem whatsoever, this is a good thing and a nice feature to have whcih will definably lend itself to extending the overall life of your engine over time.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_cd01d4e4178e5a11

Hi,
There will be a wire on the injector pump that closes the FUEL SHUT OFF VALVE. The wire may have broken or come disconnected.
You may have to ask someone to help find the injector pump.

Happy Trails.

check the thermostat, it's where the top radiator hose meets the motor in a housing

The best tip I can give---buy the manual---Chilton's is best. This is no job to try blind---you get it wrong---it's a major engine repair!