I see by your sig that you have an 86 F250 diesel.

I have an 86 F250 diesel as well and I have a couple of question that I hope you can help me with.

I have only had the truck for a short while and I am totally unimpressed with its performance. It has very little power and I only get about 10 mpg out of it.

I have a 4-speed trans and 4.10 gearing. Everything is stock as far as I know.

The problem is that the truck can't even get out of its own way going up a hill and if I put any kind of load on it (camping gear, canoe and a trailer with a couple of Sea-Doos on it) it is slow going indeed. We just took it on a camping trip and I have never been passed by so many semis goling up hills in my life!

Is this normal for an 86 F250?

It runs fine. Engine seems nice and smooth. No roughness or lurching. It just has no power. Are there some adjustments I should check?

Until now I have had no experience with diesel powered vehicles so I don't really know what to expect but I surely expected this truck to have a bit more umph and if this is as good as it gets I will need to get rid of this POS and find something else.

Also, the clutch (hydraulic) doesn't seem to disengage completely after the truck has been driven for a while. It seems to work alright for the first few minutes but then it gets hard to shift and getting into reverse is dang near inpossible sometimes without shutting the engine off first.

I have looked for some way to adjust the clutch but there doesn't seem to be any adjustment.

Any help/info you may be able to provide will be appreciated.

Thanks for your time.

Init

 

Init, I have good luck with mine, I haul heavy trailers around, so I have the power, but the economy could be better, but it is better than yours, as that's what I get with the trailer behind me, I can generally expect 13 to 15 running empty. It sounds like you may need your injection pump tuned or timed, one of the two. I also fought my clutch when I first got it, and found out through this forum that the firewall is weak and can crack allowing the firewall to flex. Ford has a repair kit to fix this problem for about $15, if that is your case too. You will have to have someone push the clutch in while you observe the firewall. Mine moved about 1/2" to 1", so that takes away from the clutch fork movement. After putting the kit in, it works fine, but the synchros are damaged for 4th I think, as I HAVE to use the clutch to shift in, rather than rpm match to shift.
When my dad has his 84 new from the factory, it was a bad pooch, 45 uphill with a medium load. Later, after the injection pump failed, many miles later, we had a local diesel shop put the pump on, and it was like they gave us the wrong truck back, it had all kinds of power. Does it smoke, or is the exhaust always clear? It should lightly smoke at full throttle, but not really any other time. If it isn't, the fuel is too lean and will make it a gutless beast. My max speed is at 75, and it runs right up there. The way mine is set up, it really likes to run at 65, it pulls best there, and runs down the road nicely. I was running down the interstate a couple days ago, and I lost no speed on the hills, no trailer.
For more info and suggestions, come check out the Pre Powerstroke forum, there's plenty of guys who can help you even more than I can.

 

Fellro,

Thank-you for your prompt response.

My truck runs fine on the flat and, as you say, it seems to like running about 65mph. It will do more but not much.

The exhaust is pretty black. Extremely thick and black when going uphill. To the point that I pity anyone behind me and I can only imagine what they are saying about my trail of black smoke (but, at least it keeps the mosquitos at bay).

I'll check out the situation with the firewall and the clutch. I'll also check in at the pre-power stroke forum to see what advice they can give me.

Thanks for your time. I appreciate it.

Init

 

The black like that is overfuel, wasted diesel. First, check the air filter, these diesels need good airflow. After that, it may get a little more spendy, but my dad's 84 is over 300,000 and that isn't uncommon for these motors to do.Mine has a fresh engine in it, done before I bought the truck, it was a real selling point for me not to mention the body's pretty clean except the box. Just gotta get the paint taken care of...