I have a 1998 12Valve 3500 Automatic. On the weekend I was pulling a gooseneck trailer with an approximate combined weight of 8,000 pounds.

I was traveling through pretty hilly terrain, but on some uphill climbs, I couldn't do more than 25 MPH. Everywhere I read, people are commenting on how happy they are with the uphill pulling power of their Cummins powered truck, so I am assuming there must be something wrong with mine. No problems when I am not pulling.

Any suggestions?

Thanks
Tom

 

In stock form I was not happy with my cummins at all for pulling. With a couple simple mods it was like a different truck. When it was stock there were some hills that I had the same problem as you. 25-30 mph over the top pulling 12k. 180hp isn't much power to pull 18-20k around. Put in a 10 plate and 3k gsk. and it will be a different truck. But I would slide the 10 plate a little back from the stock location. You will be at around 250hp so you will need to be carefull about your transmission. To be on the safe side I would up your line pressure on the automatic so you will have a little more holding power on you clutches and you tc lockup. I think DTT has the directions for increasing line pressure on thier site.

 

I had the same problem with mine in stock form. By jus slidin the stock plate it helpped mine out on the hills some.

 

Thanks for the replies. How do you know how much to slide the plate? What do you look for?

 

Do a search all kinds of good info here.

 

If you get a new fuel plate it will come with a plastic locator that will locate it off of the cover holes. You set it with that locator then remove the locator then put a couple light scribe lines on the body to mark the plate location. Then you can loosen the plate and move it tward the fire wall . I would try about 1/32 or 1/16 of an inch. This will give you less fuel thus less power than it would if it were in template position. If you beef up your trany then you can move it tward the front of the vehical to give it more fuel thus more power. The #10 plate is recommended for the 5 speed truck but it works great for the auto too. It will not give you as much power as they claim for the 5 speed. I have had it in my truck for about 5 years and I like it. It gives good power without super high egt's. I would estimate the power in the stock location at about 275hp, slid back about 1/16th at about 250hp if slid forward about 1/16 it is near 300hp. This is just a guess. I don't think there has been any dyno measurements of this for this plate. All I know is your trans is only good for about 250hp in stock form. I toasted mine in about a month after putting the 10 plate in at the stock location. The fuel plate also comes with a boost fooler that will increase your boost. In stock form your governor starts to defuel at about 2400 rpm, with an automatic that makes it fall on its face at the wrong time for the gear ratios. the 3k gsk will let it keep fueling and make the truck a lot more driveable. It won't add any hp it will just give you more room for the power to build. Make sure you increase your trans line pressure, if you don't then don't blame me if you destroy it. This is a good combo for all around use. It is not a combo for max power and torque. If you want a race truck someone else will have to help you . If you want a truck that will pull a load good and still have good power this is it. You will want to have a boost and an egt gage if you start increasing fuel delivery because thy can rise fast. I would make that a top priority if you do anything at all to increase your hp and torque. After I did these mods my milage increased about 2mpg. You will want to look at opening up your intake and exhaust too. If you look at what is in my sig you will see what I have done. You can increase timing also to give the truck more power. Just remember that the more you advance the timing the higher in the rpm range your power will be. So if you want to use the truck to tow I would keep it conservative. I have mine at 15 deg. I could have more hp If I went to 16 1/2 but I tow all the time so that is where I keep it. I am not saying you can't tow with more timing I just want to make the torque at a low rpm. Stock timing is about 13.5 or 14 deg.

 

lifer - thank you for the notes. As you, I only want the maximum available power and mileage for towing and all around driving. I have other mopars for go fast playing. I just ordered some gauges for monitoring egt, boost and trans temp.

I have been reading all sorts of posts, to try and get some handle on the theory of how the plates, starwheel, governor arm etc all work together so that I can have a little understanding on what happens and why, when any of those get changed/adjusted, I still don't really understand it all.

Are there any good writeups on adjusting the trans line pressure and on changing the timing?

Thank you and all the others for answering.

Tom

 

Where were you? Stock they are not the most powerful trucks, but I had friends that towed way more than that, and never had a problem with having to slow down that much. It sounds like there is some other problem...

Is the fuel filter fresh?

 

Northern California - Yosemite area. Fuel filter probably has about 15k on it.

Would that cause that much power loss?

Tom

 

I'm racking my brain. Do you have any smoke at all? If so what color?

Sounds like a fuel supply issue. Can you check the fuel pressure? Do you have any gauges?

 

I do have gauges, but would have to tap into the fuel supply somewhere. Where would be the best place?

The only time I have smoke is when I apply full throttle at lower speeds. If I apply full throttle at any RPM after about 1800, I have no smoke at all.

Tom

 

Are boost & EGTs normal?

Not sure the best place to check FP... But if you get black smoke at low RPM it sounds like you are getting fuel...

 

Here is some info on diagnosing fuel supply problems-
http://dodgeram.info/tsb/1996/14-07-96.htm

 

I'm not sure about the boost and EGT as I do not have gauges. I have just ordered some.

 

Sorry, I misread your post...