Bad Injector Pump? 93' 3500

[spivy30]

I have a 93' C3500 with the 6.5 Turbo Diesel with 97,000 miles that I bought used recently. When I first start it in the morning it misses pretty bad and smokes a lot but once its warmed up (about 10 mins of idling) it runs perfectly fine. If you turn it off and start it again while it is warm it starts perfect(even within a few hours of being turned off). I've been told by a lot of people that it is probably the injector pump or the injectors. Before I purchased the truck the previous owner put new injectors in it.

[DmaxMaverick]

Welcome aboard!

Not the pump, directly. Symptoms sound more like glow plugs and/or injectors (even if you've been told they are "new"), and probably a timing issue (HPCA not engaging when cold). Any combination of the above is indicated by your symptoms. Take one at a time and eliminate them. Start by testing/replacing the glow plugs, then verify the HPCA (timing cold advance) is working. If it starts cold, regardless of how "rough", the pump and injectors are the last to look at. Verify the lift pump is operating as required. Also, if you have an air leak in the fuel system, sitting cold will cause air issues, which can also cause rough starts, and take a while to clear up. Start with replacing the fuel filler cap with a new "Diesel only" cap.

[spivy30]

I noticed today that when I started it the glow plug light flashed when it would miss every once in awhile

[DmaxMaverick]

The problem is the electrical system, then. Once running, the engine won't "miss" in time with glow plug use. The miss could be power interruption at the ESS (fuel supply solenoid), reseting the GP timer. Look to grounds, poor connections, and the ignition switch.

The smoke is probably not related. Failed glow plugs/controller, worn injectors, and/or fuel system air leaks cause rough/smoky cold starts.

[Robyn]

Look over your battery cables really well.

On a 93 the RH side battery supplies power to the junction box above the heater/ac box on the firewall.

A bad battery connection or ground will cause all sorts of grief.

Side terminal battery cables, although they may look really good at first glance can be in horrible shape inside where you can't see whats up.

With the truck running, wiggle the cables a bit and see if you discover the issue.

Grounds at the battery as well as the engine can be of issue.

The crimped end at the block connection can also corrode inside and fail.

If this turns up nothing, then look farther.

Ignition switches have been known to fail internally and cause grief.

Good luck and keep us posted.


Missy

[spivy30]

Thank you im going to start checking things today

[spivy30]

I noticed now that the glow plugs dont stay engauged they just click on for a few seconds and thn go off. It would probably continue to do this all day if I left the ignition on.

[DmaxMaverick]

It's probably a loss of communication with the temp sender. When this happens, the PCM thinks it's -40° all the time. The GP's will cycle all day until it gets a warmer signal. If you have poor connections in the system, engine (and other) vibrations can cause it to be intermittent. If it's never failed to crank during a start, I suggest looking to the at the main power distribution and/or ignition circuit for the problem. This screams ignition switch, or the related circuit.