1993 W350 5.9L 360 MPFI
Alright. Still trying to get my truck running perfect. But whenever I'm pulling a hill and I put my foot to the floor, The truck will rev up, and downshift, but I don't get any more power, if anything I actually loose speed. And I'm trying to figure out what the problem is.. Fuel Injectors? Fuel Pump?.. And I was thinking that maybe the fuel filter was plugged or bad? But I traced the fuel lines all the way from the tank to the fuel rail, and I couldn't find the filter? I dont know if I'm stupid or what? Did the fuel filter ever come inside the tank?.. And also I'm starting to get horrible gas milage. Last tank was 5.5 mpg. I've tried sea foam, and a couple other injector cleaners? Any advice appreciated. Thanks!

 

have you checked you plenum and cats. i have read the magnum engines can get very gutless when the cats start to clog from the oil leaked through plenum gasket.
https://dodgeforum.com/forum/2nd-gen...um-thread.html
this is what a blown plenum looks like

 

thanks! I'm pretty sure my Cat is done! I'm about to just chop my whole exhaust off and straight pipe it, it sounds pretty bad *** with the O2 sensor pulled out LOL. And I'll have to check the plenum pretty soon here.

While I have you on the line though... I feel kind of stupid. But I wanted to replace my fuel filter, and I know that its supposed to be along the frame somewhere, and I've traced the fuel lines all the way back from the tank to the fuel rail and I cant find the stupid thing? Could it possibly be inside the tank with the fuel pump? Pic's would be appreciated!

 

i think if your truck has a fuel filter it would be mounted under your bed to the right of your fuel tank.

 

This is actually just the bottom of the intake manifold. Since it is exposed to oil, any intake could look like this underneath. The problem is the plate you see bolted to the bottom of the intake manifold. The gasket between the two can blow out due to having bolts installed from the factory that were too long, causing the gasket to blow out, resulting in a "blown plenum." This causes oil to be sucked in through the new opening, and then sucked into the motor through the intake runners. Since you are now burning oil, the cat can become clogged in short order.

Identifying whether you have the problem is as easy as shining a flashlight down the throttle body to see if you have oil pooling at the bottom of the intake. The solution is shortening the bolts and putting it back together with a fel-pro gasket. Your engine will then produce stronger vacuum, and will not be burning oil (or as much ), so it will run stringer.

EDIR: the second picture in this post is a good picture of what the plenum plate looks like when blown, although this is pretty extreme. https://dodgeforum.com/forum/2700512-post44.html

 

Thanks again guys. So I looked down into the intake through the throttle body with a flashlight and theres no puddling at all. But it does seem to have more power with my O2 sensor pulled. So I'm guessing my Cat is bad? But I traced my fuel lines again and I don't see a fuel filter anywhere. My gas milage has been crap. it went up to 6.5 this tank from 5.5. but still not good enough for my liking. Any more suggestions? Thank you!

 

i think if you fix the plenum, replace the cat and o2 sensor you will see about the best mileage you will be able to out of that setup. without the o2 sensor installed your truck will most likely run a bit rich which will cause it to get crappier fuel mileage. apparently those truck like the ntk ngk o2 sensor the best.