Good afternoon, everyone. 1994 f350 XLT, 7.3 idi turbo, E4OD, CCLB 4x4. Purchased this truck last fallwith about 125K on odometer.

Truck has been running great until past couple of weeks. Started by having a hesitation at initial acceleration, then a slight surge in power after the initial hesitation. The truck had the Water In Fuel (WIF) light come on a few times b4 that so I replaced the fuel filter/water separator. Replaced old style filter (w/water pot at bottom) with new style. WIF light issue corrected. Thought the issue resolved.

Left for a trip to CO to return my grandson. Noticed that upon coasting down one of many WY hills, w/cruise control on, engine seemed to buck/jerk a bit. Upon accelerating, bucking ceased. No problem pulling hills or on flat ground.
While in CO, truck began to be hard to start. Initially, truck fires right up like normal. Runs for a few seconds and then shuts down. Trying to restart results in having to crank it for about 15-20 seconds b4 it starts (sometimes twice), blowing white smoke and idling rough. Drives fine locally, still bucks at deceleration on a downhill. Hard to start either warm or cold. Fires right back up after turning it off and immediately restarting. Let it sit for 10 mins and again hard to start. Batteries have a good charge and starter is spinning normally.

Ideas? Need the truck for work, need to visit several work sites in a day and want it to start reliably.

 

Gas motors are my thing.
Based on little experience i've had with my dads truck/IDI non turbo, it sounds like possibly it's sucking air in the fuel system and maybe even an injection pump issue.
All the symptoms you have mentioned are similar to what dads truck has done and those were my diagnosis from getting on the net reading and asking questions. Then people making suggestions telling me where to look.
The hard to start was an o ring at the fuel heater above the fuel filter. It was sucking air from there.

I'm sure some more confident, experienced diesel experts will chime in soon.

 

Also, grab a test light and test the glow plugs for hard to start issue. Dads truck had issue with both sucking air, and bad glow plugs.
Just remove the wiring plug from each tip, then hook test light to a ground and touch the tip of the test light against the top of the glow plug. If it lights up, that gp is good. If it don't it's bad. Replace with motorcraft glow plugs.
Don't have the part# or package with me but will get it out of my shop and post the part #s soon if someone don't beat me to it.

 

if it fires, and does not stay running, the first thing i would look at is my incoming fuel pressure.
are you getting a SOLID AIR FREE stream of fuel through the schrader valve?

by your explanation it sounds like your fuel pump is shattin the bed.

what are your fuel levels?
pickups are known for falling off and creating like symptoms.

if the truck has any fuel leak at all, it will also suck air.

 

lack of fuel issue.
first thing i would look for is wet spots around the tops of the injectors, and fuel filter. the return line caps have o rings in them and when disturbed they can let air into the return line system, which will drain the fuel filter back to the fuel tank. this is why it will start and run for a few seconds and then die. the filter is partially empty and it is only running off the fuel in the injector pump and lines.

easiest way to check for air intrusion besides seeing wet spots is to remove the fuel filter and see if it is still full after sitting. if it is not full, you are getting air into the system .

 

Going out later this evening, after our 100+ *F day cools off, to check GPs and fuel level in filter. Do I check GPs with motor off? May be a rudimentary question but I'm new to diesels.

 

i would not bother with the glow plugs for now, because if they were not working the truck would crank over forever before starting and the wait to start light would only flash on for a second or two.