Will federal borrowing be too low for eager investors?

Interest rates are misbehaving.

Many on Wall Street have said the huge federal budget deficits are the cause of high rates. The federal government's sale of debt, or the expectation of such borrowing, will crowd out private borrowers and shove up rates, it is often argued.

But that is not the way it's been happening. In the last month, interest rates have dropped 1 to 3 percent, depending on the specific instrument (Treasury bills, certificate of deposit, prime rate, or whatever). But expectations for the fiscal 1983 deficit have escalated from around $120 billion to $140 billion or $150 billion or worse.

''That,'' says Peter Crawford, a Citibank economist, ''raises severe questions as to whether the markets are motivated by deficit expectations.''

Arnold X. Moskowitz, a vice-president and economist with Dean Witter Reynolds Inc., adds, ''Perhaps markets have got used to the idea.''

Looking further back, Mr. Crawford sees ''a roughly inverse relationship between rates and deficits. Rates rose rapidly in the last half of 1980 when deficit fears were mild. They dropped sharply in the last half of 1981 when, as Crawford put it, ''people were going wild about the deficit.'' Estimates for fiscal 1983, starting Oct. 1, were as high as $180 billion, assuming no changes in government programs or taxes.

Citibank guesses the fiscal 1983 deficit will be $140 billion to $160 billion , higher than the Treasury's own estimate of $115 billion. But the New York bank's James R. Lothian, in an effort to put the deficits ''in perspective,'' notes that a $130 billion deficit would be slightly less than 4 percent of gross national product, the nation's total output of goods and services. That's about the same as in 1976, when the economy was still emerging from the very deep 1974 -75 recession and interest rates were much lower.

''By that measure, allowing for the stage of the cycle, the prospective deficit is not nearly so alarming,'' Mr. Lothian writes in Citibank's Economic Week.

He also points out that inflation has been depreciating the value of the national debt. He expects this shrinkage to be something on the order of $60 billion to $70 billion in fiscal 1983, or about half of the bank's projection of the deficit. That reduces the ''real'' deficit to 2 percent of GNP, below the comparable 1976 figure of 2.8 percent.

Mr. Lothian concludes that ''anxieties over crowding out may be playing a role in the financial markets, but if so, it's a bit-part.''

His colleague, Mr. Crawford, adds that government spending as a percentage of GNP should be declining under the Reagan administration. GNP in current dollars will be growing about 9 percent a year over the next three years, he suggests. Federal spending will increase only about 7 percent. The Office of Management and Budget estimates that federal expenditures will shrink from 24.1 percent of GNP in 1982 to 22.8 percent in 1983.

Further, despite the ''indexing'' of income taxes to inflation rates, starting in mid-decade under the 1981 tax law, federal revenues should grow somewhat faster than GNP. This, combined with the effects of economic recovery, should push down the ''basic deficit,'' Crawford says.

Dean Witter's Mr. Moskowitz tosses off some more ideas contrary to popular thinking. He suggests there will be a shortage of Treasury debt in the nation, that the money markets will be eager to buy government bills and debts. His argument goes like this:

Federal deficit financing will run between $115 billion and $140 billion over the next three years. That is not an insignificant amount, but neither is it horrendous. One reason is that much private borrowing has already been crowded out of the money markets. Housing starts are running below a 1 million annual rate. They will recover, perhaps to 1.6 million by 1984. But this is less than the boom year of 1973, when they were 2.5 million. So housing will not need unusual amounts of financing.

Similarly, automobile sales are running in the 6 million-a-year zone, compared with a more normal 10 million. And capital spending has been declining for three to six months, and should decline for six to nine months more. When corporate spending on plant and equipment picks up, business will be more profitable and able to afford it. But Mr. Moskowitz does not expect industry to reach an 80 percent utilization of its capacity until 1984. Industry doesn't usually start to spend heavily on new plant and equipment until that figure reaches about 84 percent. So again, none of these areas will be borrowing heavily.

''The major borrower will be the Treasury,'' Moskowitz says. ''We think that more likely than not there will be a shortage of Treasury debt over the next several years, rather than an oversupply.''

The Dean Witter economist expects long-term Treasury bond rates to drop from about an average of 13.5 percent in the first half of this year to an average of 13 percent in the second half, 12.5 percent in the first half of 1983, and 12 percent in the second half. Mortgage rates should come down about 1 percent per year, from 17 or 18 percent now to 14 percent by 1984, and the commercial bank prime rate from 15 percent now to 12 percent in 1984.

Those remain high rates. But the drop would still be some relief for borrowers.