Top speed is killing me!

[Lee Majors]

My 91.5 auto trans 5.9 is killing me on the backroads and highway....something must be wrong.

It will NOT smoke no matter what throttle position. When you free rev there isnt even a puff of smoke out of the exhaust pipe. One would say then its burning its fuel correctly. I beg to differ as I think its running out of fuel!

its a dually so I can understand ther is a gearing difference from most trucks. But its top speed with peddle to floor board is around 68-70MPH

When I come off a stop light the truck is decently fast until 30MPH then it falls on its face. It could take well over a minute to go grom 30mph to 60ish.

I have tried to mess with the full fuel screw but with fear of a runaway condition I think I will leave that one alone. I did however screw it as far in as I could until it hit that welded on sleeve. Along with turning the star wheel a couple of clicks. With no results so I left that stuff alone

What can I do to add some decent power? I just want to be able to atleast keep up with traffic.

New fuel filter & fresh oil so I know its not that

[CumminsPride]

Fuel screw needs a few more turns after the collar is removed. I would pull the pump top to install the 3200rpm governor spring and remove the collar while the top's off. You will need a pyro for saftey though.

Next, try to find a 16cm or someones used 18.5 exhaust housing for your truck. My 91.5 had the 21cm housing on it. These do add the time to get up to speed.

My next thought is throttle linkage travel, I doubt you have enough. It sounds like the kickdown cable isn't holding the each gear long enough. My pump was pretty fresh and when they set the high idle, it would not kick down and threw itself through the gears before you even heard the turbo spool. I was in third so fast that I had no guts to pull the truck. I backed the high idle out and tighted the throttle linkage and it cured this issue.

[Lee Majors]

How much will the govenor spring change the driving of this truck? I have one on order as we speak.

[Lee Majors]

Well with the BHAF filter on the truck....I can't hear anything from the turbo...its a wonder its still there LOL

As soon as my fiance gets home I want her to mash the pedal so I can see if the throttle is getting full play. My RPM's never raise much when you mash the pedal. I know its an old truck and I don't expect it to do a heck of alot im just used to a truck that when you mash the pedal it will down shift and the rpm's will raise. In my case there is nothing I can do to get the rpm's to raise.

What position this puts me in is I can never pass someone going down the road. Besides the fact that im usually the slow traffic that's getting passed but that will be changed soon.

what is a kickdown cable? is that in the tranny?

[Begle1]

If you follow the throttle cable, the kickdown cable T's off it on a bracket behind the injection pump. When the pedal is floored it pulls the kickdown cable, and that tells the transmission to downshift.

I'd strongly suspect throttle travel. If it takes a minute to go from 30 to 60, something big isn't right. That's just wrong.

It might be another fuel delivery issue. Maybe the lift pump is totally dead or you have a big restriction somewhere.

[seeker1056]

thoughts

My truck couldnt hardly pull itself when i got it.
The lift pump was dead almost and couldnt supply enough fuel at road speed.
The timing was slightlyy off
Adjusting the fuel screw after the collar was off was a HUGE difference
The linkage from the thorttle cable to the pump was very sloppy and after taking the slop out of it that too made a huge difference

you might check any and all of these

O and what condition is your fuel filter in and when was the last time you purged the water outa it

The one i took off mine when i first got it weighed about 5 lbs it was so full of crap, and the valve was stuck so you couldnt get the water out of it.

good luck

[Lee Majors]

The fuel filter was replaced today. Since then I have not been able to start the truck and it started a huge downfall for my truck. If you read in the electrical & engine forums you can see just how deep my issue goes for today!

My truck must have a bad fuel issue....for the last couple of days it has been terrible to get it to fire over for the first time in the morning. After that its fine! im talking 3-4 sets of 15 seconds of crank time plus a healthy dose of Ether.

Thismorning I made a deadly mistake I decided to change the fuel filter before I started it the first time in the day. With it being hard to start + not having any fuel from a fresh filter posed a serious issue. Now my truck is not starting period due to this combo. And on top of that my ignition switch or something electrical is shot. When I turn the key I get nothing...no click no nothing. Headlights don't work,brake lights dont work nothing wortks. Its like something cut the wires to my battery! cables are tight and all fuses under the dash are fine.

I had to call in to work today because of this and more than likely it will take the remander of the week just to figure out whats wrong and replace it.

[Lee Majors]

Which cable coming off the injection pump goes to the transmission the middle one?

[GO OVRIT]

Check all the fusible links on the drivers inner fender. Its sounds like you've been getting air in your fuel system. Also check the vacum line that goes from the injection pump to the intake. Might want to check the valve adjustment too.

[Lee Majors]

Where are the fusable links on the driver side fender well? My fender well is pretty empty. Is it the little 3"X3" rubber covered unit attached to the fire wall with the huge cable going into it?

[PToombs]

Check the battery terminals and grounds. When everything goes dead at once it's usually a main connection. If a fusible link goes bad, you should have power to other stuff.