I've been driving my 87 (F-250/6.9 5 spd 4x4 4.11 gears 32" tires)around a little since working on it for 2 weeks solid. I have a few observations that I need some skilled advice for.

1. Good power from tip in of throttle to about half. After that it falls on it's face. Isn't rpm dependent, it does it at idle or at 3K rpm. If I back out of it to half, it picks up and runs hard.
Is it the Injection pump? Is it lack of fuel? Is this normal for a completely stock motor with the soup bowl removed?

It has a new big fuel filter. There is an inline before the electric that the prior owner installed. I will check that before any big teardowns.

2. I don't get much black smoke upon hard acceleration. I get enough to see a small trail of light black/gray smoke when you take off hard, but at higher speeds there isn't the characteristic black trail of the N/A diesel when you climb a hill and stick your foot in it. The truck came from high altitude around 5500-6000 ft. Could they have adjusted it for high altitude, since my elevation is between 1800-2200 ft?

3. The engine isn't as noisy as I remember most diesels being. It doesn't have that annoying rattle that I remember most of them having at idle. My G.F. says that it's quieter than my old truck with headers and turbo mufflers. Is this a sign that the timing is off. Occasionally I get a puff of light gray/black smoke on hard acceleration. Could the pump be retarded just a little?

Lots of questions, but I wanted to give the best description of the symptoms that I could. Overall it has lots of torque down low. If falls flat on it's face at about 2500, but that is kinda normal considering the factory exhaust and muffler. The lack of smoke has me worried though. I've been away from these trucks for awhile, but it's making me think that the injectors and pump need $ 1000 shot of maintenance. That would suck considering that I only have a little over 3K in it after buying the truck and working on it for 2 weeks.

Thanks for any info/advice.

 

I'd check the timing, if it's adjusted for high alt. you could advance it a little more.

 

Did it come from someplace like Denver where you have to pass emissions tests?
You did not say how many miles on the engine.
The 6.9 or 7.3 IDI did not have the rattle that the Power Stroke has.
Max torque is just below 2000 RPM.
The inline filter may not be letting enough fuel through.
When you said inline before the electric, are you saying electric fuel pump?
The stock exhaust is the next thing you need to change.

At 2500 you are trying to blow 607 cu.ft. of air a minute through a 2" hole, that is enough air to fill a 10' x 10' x 6' room.
At 3000 you are putting out 729 cu. ft. of air a minute.

If it were mine I would install a 3" exhaust with see through mufflers, turn the fuel up 1 flat and advance the timing two or three degrees. If you start getting a Power Stroke rattle under a load you went to far with the timing.

 

I'd advise you talk to a diesel injector pump rebuilder and have him tell you what he thinks and how to do it. that way you have it done right. I had those same problems and my injector pump need to be recalibrated and I needed all new injectors.

 

Thanks for the help.

The truck doesn't have any of that emissions stuff for no smoking. The guy I bought it from told me that is has about 40K on a re-ring and bearing job. I don't know how good his rebuild was, but most of the other work that he did on the truck was fairly well done. It has an inline electric before the mechanical pump, somebody put on one of those little screw on filters like the ones that came on the front of the old motorcraft 2bbl carbs on the tank side of the pump.
As for the injectors and pump. The guy told me that he was certain that the odometer had turned over 3 times before he bought the truck, since he knew the previous owner. It reads 94K now, so that would put it real close to 400K miles. I pulled an injector the other day for a glow-plug problem. It was original dated 09/87. I doubt that anything has been done to the injectors since new. I seriously doubt that the pump is original, since it's been my experience that the pumps are usually only good for about 100-150k miles then it's time to get a new one. I don't know a whole lot about the pumps, but I think I can figure out how to turn up the fuel a little and advance it a little by reading the forums again. I put in some rotella fuel conditioner/injector-pump lubricant/cleaner. I'm hoping that things will clean up inside if they are dirty.


I plan on doing the exhaust as soon as I straighten out some other things. I was thinking about getting a Y-pipe from summit and running a two chamber flowmaster 3" and running it out the passenger side right in front of the tire. I want to put on a turbo in the future. Do you think that 3" will support a turbo? It might be awhile since I have a lot of other irons in the fire right now. Everybody says to run a straight through muffler, but I've never been real partial to the way they sound. I have a couple of 2 1/2" straight throughs lying around. Maybe a good dual 2 1/2 with a crossover or x-pipe would help things out. It would be cheaper than buying the 3" stuff then having to get it upgraded when I buy a turbo.

Thanks for the help. I can work some pretty good wonders with gas engines, but these oil burners are really making me study and learn a lot.

 

The emission control on a diesel is cut the fuel back.
I would get rid of that inline filter I think.
I can not tell you how many gallons of fuel an hour go back to the tank on a 6.9 but the fuel pump pumps a lot more fuel through the system than the engine burns. The return line normally has a fairly good stream of fuel coming out of it.

The three inch is what is recommended for a 6.9/7.3 turbo. I have a three inch down pipe that goes into a straight through muffler. Then it comes out of that and goes about two feet into a custom Y that feeds two three inch exhaust stacks.
Truck sounds good, looks good, runs great. What more could a guy ask for from his truck.

 

Also, there's no need for two fuel pumps. Use one or the other and get rid of the other. Get rid of that Gasser filter and have the Inj's tested. I've gotten great deals on E bay for 6.9 inj's

 

Adjust timing: set to the middle setting on the notched housing. Buy 40 cetane fuel from a good source that sells several thousand gallons weekly if possible, monthly at worst. Brief black smoke upon acceleration is fine, excessive is over fueling which also puts raw fuel in the crankcase. Bad idea to self adjust w/o proper tools and stuff. Setting timing requires some skill but can be done if set as I indicated. Too much advance will increase fuel consumption, and fry the engine; too little reduces power.

Get rid of the dinky fuel filter, and electric fuel pump. Mickey Mouse belongs at DisneyLand, not your garage. Reinstall a good lift pump, and a good quality primary fuel filter and adaptor for a Detroit Diesel that will cost under $50.00 to DYI. Replacement cans are about $7.50 replaced each 10K interval, and that also adds life to the injection pump and injectors. Put it under the hood in line before the other factory filter. I have mounted several under the bed area along the frame but above the lower frame rail so it would not get knocked off.

Do not starve your engine fuel supply with the junk the previous owner stuck on. While the engine theoretically should run witout the lift pump, some will have low power w/o it. Be sure the supply side is unrestricted as well as the return side.

Emmissions controls determine how the fuel is delivered, not just cut back the amount of fuel. They want people happy with them so that they can sell more. Look at what GM did when their diesel went bad. Nobody wants that kind of rap, especially the Ford people as they have 50% or better of the diesel truck market. They also have to not add to air pollution beyond reason.

Also, it seems I remember that some may have had an issue in the intake that could fall down inside but I can't recall what it was or caused when it did. Check TSB at a local Ford dealer, preferably a Ford Truck dealer. It may have been EGR related. David

 

I believe the lift pump pressure is 7 psi . The timing is marked on the side of the pump flange, driver side/top area. They are set up to be together, advance is taking the top of the pump to the passenger side. The width of the hash mark will be 2 degrees, so dont get nuts and go too far. It is not a case where, if a little works, lots will be better. I'd get that little filter out of the line and start working from there. Keep us posted.