My 1987 F250 with the 6.9 N/A truck has been acting a little off for the last few weeks. At startup she takes longer to start and runs rough for awhile but cleans up after awhile like the engine is loaded up but cleans out. Also she will speed up and slow down while cruising without me getting on the fuel. I changed the fuel filter and filled it with seafoam and a little tranny fluid, new of course. Now I"m not getting any start. I checked the injector lines at the injector and nothing. I also checked for fuel going into the injector pump and she's getting fuel. I"m figuring injector pump died or the cleaner did to good of a job inside the pump and something is plugged. I ordered an injection pump Friday. While I"m at it I"m thinking about new injectors. Is my thinking on the pump right and also the new injectors? I replaced the injection pump a few years back and haven't had any problem till now. That was over 100K miles, maybe 200K and I"m still using the same injectors that came with the truck. Does Pensacola Diesel have good rebuilt injectors?

 

Slow start and running rough for a while could be one or more bad glowplugs but could also be an air intrusion problem or fuel supply problem. Surging at steady throttle is usually a fuel delivery problem. Therefore I would check that the lift pump is not sucking air from anywhere (water seperator canister for instance) and that the lift pump is not weak.
Also check that, with key on, you get a click when you plug and unplug the wire to the FSS (fuel shutoff solenoid) on the injector pump.

 

Your symptoms, especially the surging while driving, might be the same as mine-

The pick-up tubes inside my front and back tanks were broke off so anytime fuel went low (1/4 tank or so), or when going uphill/downhill, the engine would surge or sometimes try to cut out if idling.
And I had a air leak where the return line hooked to the first tank.

I would check the tanks and lines for air leaks.

Surging while going up a steep hill is a definite sign of air in the system due to pick-up tubes or air leak...as is stalling at a light, etc when it's facing uphill/downhill.

And mine would oftentimes have idling problems at start due to air leak...

It's really easy to check the glow plugs with a multi-meter, I also had a burst Autolite glow-plug, make sure you get Motorcraft ZD9 glow plugs to replace whatever you have.

 

The WTS light stays on for the full time. Both tanks, front and back are from full to 1/2 tank and happened after filling up at the station at times. I have an electric fuel pump just in front of the front tank. The water seperator was removed before I got the truck. I checked the FSS and it is working fine. The gloplugs are all motorcraft/Beru. I"m flat around here and very seldom go up any hills. The surging happened on a level road and would feel like I floored it for just a second then it would die till the truck slowed back to where it was before.