The acceleration principle was not suitable due to the following reasons:

Temporary Change in Demand
The principle of acceleration only works when there is a permanent change in demand. When the rise in demand is only temporary this does not necessarily induce the entrepreneurs to increase their investment. i.e. to set up new factories. Instead they employ the labourers to work over-time in order to produce additional goods so as to meet the additional demand. Thus, in the case of temporary change in demand principle of acceleration does not work.

Business Expectations
The entrepreneurs make investment keeping in view the expected rate of profitability or the MPC. So business expectations in this sense play a vital role in determining the induced investment rather than the current change in demand for consumer goods as explained by the concept of the accelerator.

Concept of Capital-Output Ratio
The concept of the accelerator explains the Capital-output ratio for the whole economy. However, in reality the Capital output ratio cannot be generated for the whole economy. This is simply because this ratio varies from one industry to another. Hence, the concept of accelerator should be confined to an industry rather than generalizing for the whole economy.

No Change in Aggregate Demand
The increase in demand for a consumer good may lead to a reduction of demand for a substitute. Therefore, with an increase in investment in one industry may reduce the investment in another industry and hence the aggregate demand for the whole economy may remain constant. In this case, the aggregate induced investment will not change and hence the concept of the accelerator does not apply.

Non-Availability of Financial Resources
The acceleration principle emphasizes that induced consumption results in an increase of induced investment. However, entrepreneurs may not always find, the financial resources or loans to increase the investment level. Hence, the acceleration theory cannot take place in spite of the fact that there is an induced consumption.

Difference in Durability of Machines
The concept of accelerator assumes that the machines used for production purposes have equal life-span and durability. However, such a reduction purposes assumption may prove to be wrong as there may be some machines that may last longer than that i.e. as a result of wear and tear.

Lack of Productive Capacity
From the principle of acceleration we find that induced consumption results in an increase in the induced investment. This means that capital goods are assumed to be easily available in the market to materialism the induced investment. But it may be possible that capital goods industries may have already been running at full capacity and the production of additional machines may not be possible i.e. in the short-run. Thus, the theory of accelerator ceases to have any effect.

Long Run Investment Projects
Autonomous investment takes place in long term projects and its known as the income inelastic investment. In the case of these projects the concept of induced investment becomes irrelevant because induced investment is income elastic investment. Thus the concept of accelerator does not have anything to do with long term projects.