Maybe someone can help with the "haints" in the motor. It's been running Ok, but just didn't have the giddy up and go it used to, I thought maybe the pods where starting to get gooped up. But I noticed earlier this week, when I "smashed" the pedal, it ran like a scolded dog. Even leaving a redlight, all I had to do was barely mash the pedal and it was gone. It's done this a few times earlier, but I just thought it was due to winter fuel, but now it's pretty hot during the day, 92-96*, and Friday while coming home from work, it seemed sluggish again. Could the overflow valve on the injector pump be screwing up, dumping fuel back to the tank and not to the injectors where it should be. Fuel filter only has 1500 miles on it since last change, I drain them and look for boogers, air filter only has 5000 miles, but I've also noticed the boost at wot being from 28 psi to as high as 31 psi. I have also noticed that the exhaust ROAR is louder when it runs better.

 

I also notice a significant difference with performance, sound, fuel mileage, and feel with my truck. Though, I can't find a pattern to predetermine better or worse running conditions in my favor.

I thought it might be variance in the fuel or humid air. By the way, how will humidity affect the air/fuel mixture??????

 

humidity means denser air, denser air means more fuel especialy if you run an intercooler to cool the the air. But i dont think that would be something that is really obvious as to performance.

 

The density of air (nitrogen, oxygen, carbon dioxide, argon, etc.) would remain the same, the density of mositure content within the air would increase as humidity increases.

When the humid air/fuel mixture enters the combustion chamber it doesn't fire as good as dry air/fuel mixture. Water doesn't fire or explode in a favorable way to create energy. Thus, more water (humidity) less power.

 

I don't believe the humidity would play that big a factor, the air temp would play into it as far as density. The colder, the more dense, hotter, less dense. But as I stated, the truck ran like a raped ape, then goes back to so so, then back to the ape. This morning going to work, I pulled the same hill I always do, but used less pedal to do it, same speed, same everything.

 

Sticking pin in the AFC? Or a sticky governor assembly. Do you run any fuel additive -- if not, it could be some fuel you buy is more or less slippery, affecting how well the governor works . . .

It also might just be the fuel filter, there could be crud floating around in it, making its flow rate vary, or worse yet, the screen in the tank . . . It really sounds to me as though the amount of fuel you are getting is varying. Try throwing a fuel pressure guage on her, between the filter and the injector pump. Bet you will see a correlation between pressure and performance. I suppose it could also be a bad lift pump.

 

I was thinking the same thing as Alec on the pin thing. In my old 89 it was jumpy like that and I found that I didn't use enough grease on the pin. After I pulled the AFC cone and cleaned the bore in the pump I put on some lithium grease (higher temp) and made sure it floated in the pump before I put it back together.

The thing is though it was just jumpy not all together slow.

 

I use the powerservice, I think that's the name of it, at every fill up. I've never had it up high enough to bump the gov, it always shifts and hauls butt, and by the time I'm running 90 or so, it's still not near the gov. When you say sticking pin in the AFC, that's the little booger sticking out the side of the hole? right. I did notice when I pulled the plunger out, there was was some "crud" on the cone area. Can you reach in there and pull the pin out, lube it up and put it back in, with out screwing things up. The "bean counter" just found out I slid a set of 5000lb air bags and compressor system by her in April, and she ain't too happy. We're building a new house and she's really trying to watch the beans so we can pay for everything on time. There goes my playing money I fueled up this afternoon at the same place I always buy my fuel, so do a lot of big trucks and tricycle dumps, it ran just fine. I have heard that the 92 models had a pump recall, how can I find out if it's still elidgeable for a new pump, I would think if it's safety related, it would not matter what's been done to the pump.

 

No matter what speed the engine is running, or what position your right foot is in, the governor is controlling how much fuel the engine is getting. So, if it is sticky inside, the truck will not perform correctly.

Yup. I don't think that you want to pull it all the way out -- just take the AFC apart, and pull back on the accelerator linkage (engine off). The pin should pop out, at which point you can dust it and give it a gentle lube with some high temperature grease.

As for the recall on the pump, you can call a 1-800 number and give them your VIN and they will tell you if your truck is eligible for recall, and if the recall work has been performed. I don't know if that number is in our tech faq or not, though . . .