Guess I need some advice here. I am new to diesel but used to working on and rebuilding gas engines. I picked up this 88 F250 7.3L stock in 2010 through a swap. I don't have any history on the truck except a pile of receipts that showed pretty regular dealer maintenance until about 2008.


I had to fix a lot of issues with the truck but the only engine related ones were to fix the various diesel leaks at the seals and fuel filter, fix the continuous oil leak at the valve covers, replace belts, and replace the radiator. Due to the transmission slamming in and out of shift points (still does but will worry about that after fixing this issue), I changed the vacuum switching valve on the side of the injector pump and put in a shift kit neither of which fixed the problem. I have regularly used Diesel Clean and keep the tanks full when it sits to avoid condensation. The truck has always (since I got it) taken three cycles of the glow plugs to start.


So, over the last year I have noticed that once in a while I will get a little surging/missing in cruise control. That has gotten worse in the last few months. Just a few weeks ago I noticed in my mirrors that I would get a pretty good puff of blue smoke while on the highway. Doesn't happen very often so not sure but think it is when letting off on the pedal. The apparent "miss" now has gotten pretty bad just with normal driving around town or at highway speed.


Looking for ideas and suggestions on where to start first on the engine problem and then some follow on steps to part replacement, diagnosing and hopefully repairing it. Once I fix this problem, I will probably change out the transmission or at least get a new valve body.


Thanks...

 

Sounds like you might be due for a set of injectors. Try the ATF in the fuel filter trick first though.

Have you replaced the modulator on the transmission yet? You've covered most of your bases, take a look at vacuum as well.

 

Didn't know about the ATF in the fuel filter trick.. How much do you put in it?


Is it much of a problem to change the injectors? Since I don't know the history all that well, I was thinking of doing that just because (not sure the cost though)..


I tried changing the modulator but that didn't seem to do much for the shift problem.. It's been a while since I checked the vacuum but thought it was ok the last time I checked it.. Will do that again..


Thanks....

 

You pull your fuel filter, drain it, fill it up with ATF, start the truck up for 30 seconds to allow it to get to the injectors, shut it off and let it sit for 24 hours. The high detergent levels in the ATF will clean the innards of the injectors and IP.

Injectors aren't too difficult a job and price isn't excessive; especially compared to the prices of injectors for modern diesels.

 

the hard shifts under full throttle is a thing with the diesel C6. mine does the same thing, really bangs into gear when i am in it. but if i am granny driving i almost don't feel it shift.

 

Hey, thanks for the info on the ATF for the injectors... It will be a while before I can try that as I am out state right now on a job but will do it as soon as I get back.. If that works, then I will know its getting close to time to replace them and, if that doesn't work, I will go with new injectors anyway..


My trans bangs all the time unless I let off on it right before it shifts and even then it does it sometimes.... What do people do if the vacuum valve on the IP goes bad since it is no longer available?.. I am thinking that even though I replaced mine (with another used one) that might be the problem with the shifting..

 

you can still get them new off evilbay.
http://www.ebay.com/itm/NEW-OEM-Ford-Transmission-Vacuum-Throttle-Regulator-Valve-TP-Sensor-7-3-Diesel-/251276815393?pt=Motors_Car_Truck_Parts_Accessories&hash=item3a8143ec21&vxp=mtr

 

Great, thanks for the link.. I gave up looking a couple of years ago but should have tried again... Will go order one...

 

before throwing money away on a part you may not need, have you tried setting/testing it?

 

No, I am out of state right now and will only be at the truck a couple of days in mid-February so thinking of lining things up in advance in the way of parts... Doesn't hurt to have a spare...