Why 1991 volvo 940t engine start but without power at all?

No you don't but you may need to remove the radiator if you have big hands like me to get all the space needed

I would try cleaning the Electronic Idle Air Control Valve with a trusted Electrical Cleaner then a Non-Conductive Lubricant.

check the basics like air filter so its getting clean air make sure the throttle body plate is clean change the spark plugs of there old

If the speedometer and odometer are not working the problem is usually lack of signal from the transmission speed sensor.
But if the cruise control works and the speedometer does not, my guess would be a problem inside the cluster.

1991 Volvo 240 Model

This model was fitted with a 2.3 litre 4 cylinder fuel injected engine

Does the current owner of the vehicle have well kept service records? If he does, ask him if the timing belt was changed on this car. And ask him to show you the service records. The timing belt should have already been replaced, but if not, you will need to replace it immediately. Along with water pump, seals, and balance shaft belt. If the vehicle has an interference motor, and the timing belt breaks going down the road, it has the potential to ruin the motor. The timing belt on a Volvo is not for the beginner, and most shops will not even touch it. Tech will need special tools to lock down the cams, or risk even bigger issues. Also, do a visual inspection, paying close attention to the undercarriage, looking for oil leaks. Volvo's are great cars, but the routine maintenance can be costly.
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try adjusting the throttle position switch very hard to adjust right car will hesitate , not idle properly and hesitate when accellerating if not adjusted properly.

The fuel pump is located in the fuel tank beneath the back seat which you can reach by removing the back seat.

Cheers.

I believe this a belt driven engine right? Check the timing belt.

One of those relays supply power to the injectors. They fail, as well as the fuel pump relay, rpm sensor, and the main pump. Have you checked the trouble codes in the engine or ignition computers?

Bret
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