My buddy just bought me his 1999 5 spd 2WD truck and said it quit after leaving a stop sign and going into 3rd gear made a POP sound and died. wont start anymore.
The only code is P1688.

I think that is injection pump related but that doesn't explain the POP he said he heard.

This thing will not stat and run at all.
Any suggestions?

 

The pop he heard could have been the effect of altered pump timing, delivering fuel at just the right time to cause a backfire, or perhaps a late shot that went out the exhaust.

P1688 is a death code for the pump. Period. See that one, and the rodeo is over.

Good luck with it

 

Mine popped really loud when the pump went, there was a small cloud of smoke. When I say loud I was expecting to see a hole in the block, I was in the process of passing a car.

 

Thanks for the quick replies.

 

With everything being new I would check the connection(electrical) on everything, also I would make sure you are getting fuel to the IP, if you bump the start you should hear the lift pump run, if you don't you need to check the relay on the fire wall. Its the on that goes to the small grey connect that use to connect to the LP on the side of the block. After you know the fuel pump runs, then I would make sure fuel is getting to the IP, crack the line on the side of the IP and bump the start, you should have fuel everywhere. After that, I would crack a few injector lines and see if you get fuel at the injectors, you should get alot of fuel after a few second of cranking.

 

Holy crap!!!
These thing are spendy.
Where is the best place to get one of these things?

 

Disregard the last post.

Just got off the phone with Thoroughbred Diesel.
Thanks again for the quick replies.