A friend of mine has a 94 2500 2wd dodge diesel pickup that has trouble cold starting. When it is below 40 or so it will start but it will smoke alot of bluish smoke and will barely stay runnung. When you step on the throttle it is like it is not even connected, the engine shows no sign of increasing rpm. Once it warms up for 20 or so minutes it runs great but for the first 20 minutes or so it really runs bad. We changed the fuel and air filter and those made no difference. Any help here would be appreciated thanks

 

Maybe start checking fuel pressure and check for vacuum in the return line. The Haynes manual covers alot of diag info.

 

Hard starting usually has one of two causes. The easier one to check is the grid heaters. Take a voltmeter and measure voltage from each lug on the heaters to ground while the key is in the on position. Each of the two lugs should show 9 or 10 volts to ground. If they don't, the most likely cause is that your grid heater relays have gone bad.

The other possibility is that there is an air leak somewhere in the fuel system. These can be hard to diagnose because they are so small that you can't see them. THe most likely causes of this would be old fuel lines, a burned up fuel heater or an improperly installed fuel filter.

There are other things that this could be but these are the two most common. Checking the grid heater relays is really easy so start there and let us know what you find.

 

he is plugging the block heater in, right?

 

I will check that this weekend and yes he is plugging the block heater in

 

Are you sure the heater is working? Just because it plugged in doesn't mean it working. I had to replace my plug end. Is there heat coming from the block or top radiator hose? Thats a good way to check.

 

At 40 degrees, running the block heater should not be necessary at all. It will help some if the truck really doesn't want to start but there is something else going on.

 

There is a filter screen in the fuel heater bowl- cost around $10 last time I changed mine- might also be a good idea to change it. (I did mine at around 80K)

Sounds like it may be burning oil?? Blue smoke, as opposed to white smoke (from cold cylinders). Really, sounds like the manifold heaters are not working- I knew someone with a Freightliner that had the B series and no manifold heaters, it was really cold blooded until it warmed up, and would fill the yard with smoke (mostly white) on a cold start.

 

Agreed - I don't use mine until it's below 5*F. I wonder if it's a low compression issue?

 

I still have not had a chance too look at this problem further but I dont know about compression it only has 120,000 miles