My truck has lost power, 70mph wide open and drops to 45mph on a hill(Empty). I have replaced the lift pump 5000 miles ago and fuel filter today. seems to be starving for fuel. The truck has 368,000 miles and I have no idea on the injectors and injection pump. Has no smoke and is getting great milage 28mpg last tank usually 20mpg.

Any ideas on the loss of power

Thanks Jeff

 

Check your timing, also, I can't remember how the 2nd gens stop the fuel to the pump. If it has a cutoff like the 1st gens, make sure it's opening all the way. Second gens also had a problem with the rubber fuel lines swelling, caused loss of power and hard starting. There was a kit available aftermarket that included better and larger lines.

 

I had problems with the fuel shutoff and I put it on a choke cable but it works now. I think they are either off or on.

 

Check the prefilter (in the fuel heater) and it might not hurt to check the in-tank filter also.

 

Sounds to me like you might have a boost leak if the timing hasn't slipped.

 

I'd check for fuel at the filter, then check the overflow valve and pressure to make sure you have at least 20 psi at idle, then I would check the timing.

 

Check your intercooler boots. Especially the lower ones, they can come in contact with the sheet metal on the inner fender well and rub a hole in them. With the great mileage, it sounds like boost leak.
Also, with the age and miles on you truck, I'd replace fuel lines(tank to lift pump) they get old, leak air/fuel. But check you boots first. i got new ones from stylinmotors.com. Cool blue color,new clamps, very HD.

 

If you have gauges, you could diagnosis this better, if you have high EGT and low boost pressure, its probably a boost leak.

 

The most likely causes of a boost leak, clogged prefilter or the fuel shutdown solenoid have been listed above. The easier of the two to check is the shutdown solenoid so I would start there. When the truck is running, see whether you can push it up any farther. Also, try zip tying it up as far as you can get it to go and see whether the symptoms go away. Then next thing I would do is check the prefilter screen. Even if you don't have a new one waiting to go in, you can clean out the old one well enough and it only takes maybe 5 minutes to change. It is in the little puck shaped thing just forward of the lift pump on the driver's side of the engine. If that checks out okay, then start looking for boost leaks. This can be challenging to do but the first place to look is for abrasion on the boots. Then, if that doesn't work, try some soapy water in a spray bottle and look for bubbles with the system pressurized.

Good luck.

 

No smoke, No power. Check for air leak into fuel line. Look very carefully at all of fuel line for damage or deterioration. Sometimes you can apply very light pressure to disconnected line and find leak in reverse.

 

If it was a boost leak, there would be more smoke. You need to get fuel pressure readings. Make sure your throttle cable is within spec. Check the AFC housing. Maybe you need to adjust your governor arm or fuel plate.

 

If you fuel pressure checks out, you could have also ruptured the line that runs to your afc. This line is hooked to a diaphram in the afc which controls the amount of fuel that will be delivered based on your boost pressure. If the line ruptures, it won't see much boost pressure and won't deliver much fuel. Depending on how the afc is adjusted you don't necessarily get a lot of black smoke with a boost leak although you will get some probably.

 

The fuel shut off is definitely not just on/off.

You will have very substantial power loss partway through the levers movable range.