Cummins Diesel Forum banner

well i got a problem. needs some input

1K views 18 replies 5 participants last post by  tylerjwitty 
#1 ·
i have a 1990 5.9 4x4 and a 1993 5.9 2wd. both I got in the last two months and have been the first I have ever driven.

The 1990 always seems lazy and I figured that was just an old cummins and how they work.

Than I finally got the 1993 on the road and frig, she sets you back a wee bit when you stomp on it.

1990 seems to get more and more lazy the hotter the temp is outside.

so my concern is this, is the 1990 got some issues or performing as it should and the 1993 has had mods done or ..

basically what are these trucks suppose to do
 
#2 ·
It's the free mods that give it more power, look to see if the tamper proof covers are on the power screws. That will tell you if they have been turned.

As the pumps get some miles on them you sometimes need to turn them up so it will move.
 
#3 ·
Sorry forgot to add

I turned the fuel pin . Star wheel bottomed and smoke screw turned in .

1990 looks likes the pumps been into before as everything was millwright wire .

1993 all adjustments covers are on .

I wish I knew the history on these machines. I don't anything about the injectors , gov spring turbo ... Ect
 
#4 ·
Which one did you make the adjustments on?
 
#7 ·
So your saying you bottomed the starwheel and turned the smoke screw in on both of them?
 
#8 ·
Oui senior . The fuel pin , star wheel, and screw are both adjusted to the same point . How would I confirm a 366 spring is in the the 93 .

The difference between the two is enough that my wife comment on it and she doesn't care that much.

The 93 is more peppy on a tap to the go pedal while the 1990 takes about .5 - 1 sec to work up to it ..

Maybe air filter on 90 is slightly plugged
 
#10 ·
The gov. spring doesn't make it peppier it only gives it more RPM up high.

Are you blowing alot of smoke on either truck?

Alot of things can cause a slow truck, dirty filters, bad injectors, a badly tuned IP, a bad LP.
 
#11 ·
No I wouldn't say I'm blowing a lot of smoke . On start up in minus 2 c we have had the last few days


1990.
New fuel filter
Installed electric fuel pump(wondered if the lp was bad )
I should try a run without the air filter on it to see if anything changes

For example the 1990 on the mat on a medium grade hill might gain slight speed and the 1993 will gain a good amount
 
#12 ·
Do both of them have the same trans., tire size, gear ratios in the axles?

Are they both 2 wd's or 4x4's?

It would be hard to compare the both of them unless they are identical trucks.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top