Nissan Repair: 1997 nissan delica diesel, haynes manual, injector pump

Question
Hi, my nissan runs unevenly, especially noticeable at cruising speed. The auto will drop into & out of overdrive regardless of gradient. The engine revs vary from 2600 to 2800 then 3000 then back to 2600 or 2800 for no reason. The computer control on the injector pump has been replaced(this showed up as faulty on the computer diagnostic) & this improved it. (it used to stall going from forward to reverse) but did not fix the problem totally. I have been told the fault could be the accelerator switch but as this is $500 & only available ex japan i am reluctant to spend this without getting more info first. can this switch be fixed or could the fault be something else? Regards, Kevin  

Answer
Kevin,

It could well be the accelerator switch but you need to check out the fuel pressure to make sure the regulator is not plugging up.  Check the fuel pressure and if it is within range next would be the switch.  I would get a manual with the specific values and ohm it out before I spent the money.  Switch is not rebuildable so check it before you spend the money.  A Haynes Manual or a factory service manual will have the values.