intermittant no start?

[WHITEY]

A friend of mine has a 99 2500 with the 24 valve cummins. At times it wont start. If you would turn the ignition to start and crank it, it wont fire. Now if you back of on the ingnition switch towards run it will fire and run. Hmm, Maybe the ignition switch. Not. Replaced the switch and the key tumbler. Still nothing. Replaced the cps on the side of the motor near the starter, still same problem. Ocassionally, while running it will shut off also. Any Ideas?

 

[holtzer1]

so, if you turn the key to the full forward crank position it wont crank/fire,,,but if you back it off a smidge it starts up? if so, your problem is within the column.

 

[Swany]

It will shutdown while running too? Sounds like it's shorting out somewhere or a faulty CPS (even new ones are sometimes bad)

 

[WHITEY]

I can't think of anything else in the column to replace. What are possibilities of a bad ecm, or injector pump? A dodge tech told me to replace all the battery terminals. Did. No go.

 

[haz-mat19]

Mine cranked but would not turn over. It was a bad l/p. But it could be something else. Try checking your fuel pressure. Good luck.

 

[WHITEY]

I have checked fuel pressure and it is normal. That is why I seem to think it is some part of the electrical system or sensor?What is required to start the engine? Sensors, etc. What does the engine rely on to stay running? On the ford, it is the cps. On dodge, what is it referred as?

 

[holtzer1]

ok required to start, ecm, good i/p signal, too much to list actually, heres a common problem i found, take off the under hood fuse box, turn it over and look for corrosion on any terminals, i've found quite a few with bad connections under there, all of your relays and whatnot go through that. does the tach move while cranking during your no start condition? has it been scanned for any dtc's? if not, get it scanned, it may lead you to your problem in less than 5 minutes. try this and let me know, i'll think of some other common probs.

 

[holtzer1]

and to answer your question, what you refer to as a cps...crankshaft position sensor, is internal to the i/p, thats why you need a scanner, or if the tach dont move while cranking...most likely cause is the i/p, thats where your tach signal is derived from.

 

[WHITEY]

well, I scanned the truck and code 1688 came up. Internal injector pump failure. Also while cranking with a no start condition, the tach does not operate. Looks like it is farewell to the injector pump. By the way dodges list on the pump is $4250.00.

 

[Whit]

I would not go to the expense of a VP-44 yet, do the crank positioner first, reason I say this is that if the CPS isnt getting a signal then itcould set a code for the injection pump............so that code may be bogus, also if it doesnt turn out to be the CPS then you could store it for a later date or sell it and maybe get 80% of yer money back

 

[holtzer1]

code 1688..internal i/p failure...thats dead balls accurate, there is no diagnostic procedure for this code except, replace i/p, youll be wasting money on any sensors you buy, with that said, the price you posted for the i/p from dodge also includes the core charge, i would find an aftermarket i/p anyway unless its over 100k, buddahpower.com has a killer pump, i think thats how its spelled,

 

[holtzer1]

under 100k i meant

 

[holtzer1]

any updates on the truck????