i have a couple post on here and origanly my map sensor said it was bad but truck would still start i have not had time to fix map sensor but now truck wont even start is this cause of bad map sensor or do i have other issues my obd2 came up with 1688

A 1688 code is for your fuel pump. First, we need to know what year odf truck you have and all of the "extra" you have. Some thongs you can do to get started are: Bump the starter, you should be able to hear the pump run for about 25 seconds. Next, disconnect the fuel line from the pump to the injector pump. Bump the starter, fuel should be pumping out of the line. If you have no positive action on these two steps it is time for a new fuel pump most likely. But, we need to know more about your truck for a definate diagnosis. This will get you started. Repost wth all of the info!

P1688 is a injection pump failure... Replace the injection pump to get it running... http://forum.mopar1973man.com/showthread.php/2627-P1688-Internal-Fuel-Injection-Pump-Controller-Failure?highlight=p1688 But it would be nice to know what your fuel pressure is too... As for the MAP sensor it will run still with a bad MAP sensor it will even run without but in limp mode for both...

when i turn key on i have 15lbs of fuel i have the cater campiagn pump my truck is 01 have 4inch exhuast edge comp bd toque lock and pac brake fuel,pyro,boost,and trans temp guages i thought i put all this on my sig