I just bought a 1991 1 ton dually 2 wheel drive and its completely stock. I just went on a trip and pulled a 8,000 pound camper and I had no power up hills. Max speed on the interestate on level ground was 55-60 mph and my mileage went from 18 mpg empty to 7.5 mpg pulling only a 8,000 pound camper.

What can I do for more power and better fuel economy on this engine? Any suggestions?

Thanks

 

Sounds like the 97 in your sig is more than set up to pull the camper, so I'd just use that In all seriousness, check the sticky at the top of the 1st gen forum. All the tips and tricks you need to make your '91 perform bertter are right there. Is it an auto? Intercooled?

 

what gears do you have? Have you turned your pump up yet? If you do make sure you get gauges. You could always upgrade to a bigger down pipe exhaust, injectors and turbo.

 

Get it breathing good and add a little fuel

Most importantly, is it an auto or 5spd?

If its an auto you no doubt should upgrade the torque converter before anything else.

 

Something is definitely wrong with your truck. I also have a bone stock 93 D350 and have used it to haul a 4,000 pound truck camper and a 8,200 pound 5th wheel. Never had any of the problems you descibe. Acheived 22 mpg empty, 14 mpg with the camper and 11-12 mpg with the 5th wheel. Only issue is with transmission slipage going up long grades and then I would punch it out of overdrive.

 

Yes the truck is an automatic. Yes the 97 is set-up for pulling but now I will be useing the 91 also and so I need to modify it.

I am thinking of putting a P7100 pump on the 91 as one of my mods and a bigger intake setup and aftermarket air filter.

The pump on this truck isn't turned up at all. It doesn't even pump out any black smoke out the exhaust. What can I do to turn the pump up until I put the P7100 pump on?

What injectors and turbo do you guys suggest? This will be for pulling a variety of things and sizes all over the country.

thanks

 

Sounds like a non-intercooled truck? No need for injectors, they are already plenty big. You need a better torque converter, and if you want to run fast on the highway and get good mileage you are gonna need overdrive.

 

The truck is intercooled. and i believe it does have overdrive as there is an OD on/off switch on it.

 

if it's intercooled it's a late model 91 which means smaller injectors, intercooler, 4spd auto (4th is OD) and either 3.55 or 4.10 gears.

First thing I would do is make sure you're getting full throttle travel and rotate the fuel pin. Make sure all filters are good and clean too.
My truck was a turd until I did that. Apparently I wasn't getting full throttle because the pedal cable stretched.

I wouldn't bother with the p7100 pump unless you want big hp, the VE is a great pump.

 

Really there is NO point in a P-pump with a stock trans.

Something you may not realize because you own a 2nd gen. Is the 1st gen automatics are non-lockup, so the converter is always slipping and it just so happens the factory one is a POS unefficient high stall turd that is the total opposite of what they should have put behind the cummins.

A 5 speed swap or a good converter ($600-$1000) will help alot, or you could swap in a 94-95 47RH lockup auto out of a 2nd gen. And buy a good converter for that and you'd have lockup. right now with the 91 trans you have just overdrive.

Check out the sticky and look at the videos in there on how to turn up the pump. The links will take you to my youtube where i show how to turn up the pump..