hi i was just wondering what exactly in a ds4 pump fails when you get codes for fuel solenoid response time too short everyone just says needs a new i/p just want to understand what has actualy gone wrong with the pump

The closure time has exceeded range (1.75-1.90 ms). The fuel soleniod wears out overtime and without lubricity additive even faster. It is a cap wired to move an armature plate attached to a rod that closes the plunger, allowing fuel to pressure 1 of 8 lines.

so is it a part that is replacable with out rebuilding the pump or does the whole pump have to come apart to work on this piece my cousin's van came up with this code today i understand the logic that if you are going to remove the pump you might as well rebuild it but the mechanic in me wants to play and learn lol:D maby i will have to disect one of these things everything i own is mechanical only thing with a computer i have is my house:lol:

If your asking if you can buy a solenoid and put it on yourself, or repair the one you have, the answer is no. Only place that can repair/replace it is a Diesel shop. And its not likely that they will just fix your Closure Time problem. Lots of updates that may need to be applied, depending on how old the pump is. Not really a 'cheap' way to get out when your talking about DS pumps.

If you get a new cap, armature, rod, screwand orings you can do it but you have to take it off the truck and you have to set the armature travel to .005" or it won't work. A new/rebuilt pump will serve you better in the long run.

There's a lot more pieces inside there too. No doubt yours will need normal wear and tear parts, get a rebuilt and a warranty and then you don't have to worry about it.

By the way, you'll spend atleast $400 if you buy a new solenoid, armature and cap, and then you'll try and put it in yourself and sieze the head, and then you can buy a $900 head and rotor and pay to have your pump rebuilt.

Also caused by bubbles in fuel, as in low tank fuel level, when braking or cornering.

i am not looking for a cheap way out or anything i am just curious about what wears out or what the cause of these issues is it is not even my truck just a quest for knowledge and understanding):h

Fuel solenoid, armature, cap and/or spring. Any one of those that gets worn will throw your CTIME out. It doesn't take much, its only a 0.4ms window (1.5-1.9).