i have just put a new pump on my 98.5 cummins and it started to skip and idol funny. the fule econmy also droped. what could cause this? i have tried every thing i can think of.

 

Welcome to the site. Need you to fill in your signature with your truck information so we know details about what you have. Sometimes this will completely change the answers when we see different things in there.

Just from the info given, I would say that either the pump is bad right out of the box or some sir still in the fuel lines. Do you have a fuel pressure gauge hooked up to the system that you can see at all times and if so what pressures is it runnin and if not you really need one ASAP. This $50 gauge will save you replacing a $1000 plus new pump again.

 

no i do not have a fule pressure gauge on the truck. i have also replaced the apps. but the code on the truck is 215 i think. it has been a while since i have checked it. the truck has ran about a year like this.

 

Did you reset the APPS after the install. The truck has idled funny and skipped for a year now or this is just after the pump install.

Sorry for all the questions but to diagnose over the net means we have to understand details of it or we end up missin some stupid little thing that makes all the difference.

 

yes the truck only skipped after i instaled the pump. do you think it could be the iat sensor or does my truck even have one. my code reader was saying that there was low voltage to the throttle position sensor be for i installed it but after i installed it said high voltage. dont know if this has anything to do whith the problem but it might help.
also the place i bought the pump from has since gotten a bad rep for bum pump computers.

 

Here is a good thread for info on the IAT sensor, how to clean and diagnose it. https://www.dieselbombers.com/24-val...html#post78417

I would also suggest dis-connecting the Superchip just to make sure it's not the problem. Going from your signature I will also tell you that no VP is ever gonna last you to long with just using the stock Lift Pump. In stock configuration these fueling systems and LP are just barely adequate to supply enough fuel at factory horse power levels. When you added that chip to the truck you dramatically increase fuel delivery needs and even in perfect working order the stock LP will not deliver enough fuel to keep you from running the VP dry if your hammerin the go pedal. This is where the Fuel Pressure Guage comes into play, so that you can see when your starving the pump for fuel. The VP-44 not only uses the fuel to make your truck run it also uses extra fuel as the cooling method for it's electronics. So when your not moving enough fuel it overheats and fries the electronics in the pump.