91' F250 7.3 I.D.I. coughing.

[mikeboggess]

My truck has recently started coughing after the high speed idle cuts off. It also has a grayish smoke coming from the tail pipe. It has also cranks over way too long before it starts. Water in fuel question has been eliminated. Could it be glow plugs? Glow plug regulator? Smoke disappears after truck is driven down the highway. My mechanic has it now and is thinking one or more glow plugs. G.P.'s have not been changed in years.

 

[bbjordan]

When was the last time the fuel filter was changed?

A restricted fuel filter can lower the fuel pressure at the IP which will retard the timing. Gray smoke is an indication of retarded timing.
The coughing when the high idle kicks out is not a glow plug or regulator issue. The temp of the engine is 120* when the the high idle kicks out. The glow plugs should be off long before that.

 

[Trevtron]

Was thinking air and fuel filters are a good start