Forgive me in advance...I'm a newb and I'm not near the truck right now.

OK, I used to have a '90 / I-6 / M5OD / not sure about the rear end.

I sold that truck and bought a '95 / I-6 / M5OD / not sure of rear end in it either. However, I do know that the gearing is "shorter". Meaning the 95 won't go as fast in each gear as the 90.

The 95 idles, accellerates and cruises smooth, gets about 16-17 mpg on the hwy (I think) but, it doesn't accellearate as fast as the old truck. The difference is really noticable to me. So I cleaned the injectors (several rounds of seafoam), plugs, wires, filter. I could tell it helped it idle and run smoother but it is still slower. Checked the brakes, they're not dragging.

I kindof forgot about it and learned to live with it till this weekend when a friend borrowed it and said somethng about it.

So what do you think guys? Let the ideas flow.

I wonder if the cat is "plugged" a little, not letting it breath. That's about the only thing my newbie mind can come up with....which might not be possible. I thought I might cut the cat out, install a temporary straight pipe and see if that helps ? ? ?


Thanks in advance ! !

 

What size tires do you have on the truck?? Look at the VIN sticker on the driver's side door jam-near the striker plate and see what the axle code is. Should be a two character code.

Those 4.9 sixes should have good low speed torque-unless the overall gearing is too high because of tire size or axle gearing.

 

check timing. remove the spout connector first. alot of the 4.9 are shearing off the roll pin in the distributer gear and the timing slowly gets further off. if its off a ways, set it and drive it awhile and recheck. if it move again its the roll pin. While your setting the timing try it at about 13 or 14 degrees. just make sure it dosent spark knock. it will wake it up some.

 

Thanks for the ideas so far.

OK, I checked the axle code, it's 17. The sticker calls for 235-75-15 tires, which is what's on the truck.

I've got a Haynes manual at home, I'm sure it can walk me through checking the timing. I guess I need to pick up a timing light on the way home? If it is that pin sheered off, would that mean a new distributor, or just a pin, gear? And, what do you mean by the "spout connector"? WIll that be identified in the manual? Thanks guys....

 

That code 17 means that the axle ratio is 3.31 with an open differential. It could be that your other 4.9 truck had a 3.55 axle. But you said that this present truck has lower speed in each gear of the transmission. The 235 tires are short and wouldnt be the cause of low power.

May want to check the initial timing like the previous poster suggested.

 

haynes manual should cover the spout conector. it should be near the ignition module on the drivers inner fender. if it is the pin in the dist. gear, you can match it up at a parts store for less than $1.

 

OK....nice. If anyone has any other ideas feel free to jump in. I'll "attempt" to check the timing tomorrow and report back......

 

Timing is most likely your problem, but check fuel pressure anyway it should be upwards of 50psi with vacuum removed from the FPR.

 

I've been trying to borrow a timing light from someone. Not as easy as you might think. I flashed back to this old post of mine:

https://www.ford-trucks.com/forums/7...t-is-this.html

So I decided to take it out....to try and get the truck back to it's original state. It seemed the 4 bolts holding the throttle body on were not really tight. Anyways, I took the spacer out, put the throttle body back on and....HOLY COW. It runs like it should ! ! I'm kicking myself for not taking that thing off a year ago. Was it the spacer? Was it the loose bolts? I don't know.. I'm still trying to find a timing light as well. Thanks for everyone's suggestions. Nice to have good folks like ya'll around!!!!