[DieselRacer75]

If you guys have any idea what my truck is doing please let me know. It has done this for about a year now and it is very random about doing it. It might be fine for two months and all the sudden it will do it for a few days and then back to normal. Watch the video and tell me what you think... :thumbsup: Startup001.flv video by DieselRacer75 - Photobucket

 

[huuhcummins09]

Do you have an aftermarket lift pump cuz i do not see one inyour sig?

 

[12vrichh1989]

huh kinda baffles me. my dads 24v does that if its parked flat, it its parked forward starts right up. sounds like somethings plugged then it clears out. could be a few diff things, mines never done that but when we did the 12v swap everything was new so i havent had this happen to me. the pumps all stock? brand wise

 

[DieselRacer75]

Do you have an aftermarket lift pump cuz i do not see one inyour sig?

Its a new/stock lift pump. Do you think that could be the prob??

 

[DieselRacer75]

huh kinda baffles me.the pumps all stock? brand wise

Ya it baffles me to!!! What pump are you talking about? Lift or Injection?

 

[huuhcummins09]

Well I do know that a stock lift pump is not going to be able to supply the proper amount of fuel to your P7100 with the list of mods. that you have. So yes it could possibley be the problem. If I were you I wold go aheas and get an Air Dog or FASS.:headbang:

 

[12vbigkermit]

check your return lines. make sure you are not leaking. i had the same prolbem on my truck after i put my head on and it was a line going to the fuel filter. If you drive it does it drive fine? after the sitting for an hour or the night is it hard to start?

 

[DieselRacer75]

check your return lines. make sure you are not leaking. i had the same prolbem on my truck after i put my head on and it was a line going to the fuel filter. If you drive it does it drive fine? after the sitting for an hour or the night is it hard to start?

I just replaced the lines and there are no leaks but yes if it sets over night it will do this. :banghead: Sometimes it will do it if it sits for about 3 hours but normally its win it sets overnight.... Keep the comment coming... Every little bit of info helps. :thumbsup:

 

[Watchdog]

Sounds like your draining fuel back to your fuel tank possibly a bad filler cap vent alowing the tank to go into a vacuum then when shut down pull the fuel from the lines back to the tank. Only a guess but having to prime the pump says that the fuel is running back when you shut it off. Does your lift pump come on when you turn the key on it should run for a few seconds then stop?

 

[ykdave]

I would make another vote on it loosing prime. Definately sounds like its running out of fuel.

Have you checked/removed the fuel preheater? It is a common source of an air leak on the suction side of the lift pump.

Check out joeGs writeup for some info on the common leaks

http://www.cumminsforum.com/forum/94-98-tech-articles/58777-joe-g-s-fuel-system-writeup.html

 

[12vbigkermit]

look on the return lines of the injector. see if you are leaking there. and look on driver side of bock to see if its leaking check will running.

 

[simplyred67]

sounds like what my Dodge is doing ...only diff is mine isn't starting at all now...drained my batts trying to start it ...probably am cooking my starter also!

 

[fro10987]

You are defintely running out of fuel plain and simple. Weather it is due to a plugged filter in the tank or a plugged filter on the motor sounds like time to do some diagnostic work. I would start with a hose stright from the lift pump inlet to a 5 gal diesel can. I am assuming your tank is not plum full as the return will overfill the tank if it is. This will tell you if the problem is in the tank or after the LP. If you still have the preheater hooked up follow Joe G's advice to remove it. If it does run fine from the diesel can it is either something in the tank or lines to the tank, unless you still have the preheater in there then it could be in there as well, but like all good 12 valvers that is long gone right!!! From what I have read if it runs good from the diesel can it is probably a crack in the line or a bad connection in the fitting at the tank. When you take the rubber line off of the steel line at the front under the driver door you should get fuel coming out relatively easy and steady. No chance anyone reversed the supply and return lines under the truck correct?

If it does not run fine from the diesel can then I would have to pint towards the fuel filter on the motor which I would guess has already beed drained and changed and has been run long enough to bleed the air out of!

Joe G's fuel write up is very clear and easy to understand if you have not yet read it do so from start to finish. The fuel system is very simple.

 

[DieselRacer75]

Well i cant really do a test on it because it's so random about doing this. when i posted this about a week ago it was doing it every day.. Now it has completely stopped.... But I'm going to look at the lines as soon as I can. One other thang. Every time I pull my gas cap off there is CRAZY amounts of vacuum in the tank. Its like my cap isn't venting. Could that have any thing to do with it?? I know it sounds stupid but my dirt bike wont run if you plug off the gas cap. So is it the same for my truck?

 

[jknowles4]

My truck was doing this exact thing a few weeks ago. I changed the fuel filter and cleaned the pre-filter and have not had a problem since. When was the last time you changed the fuel filter? Even if it is new you could have gotten some really bad fuel or sucked up something that was in the bottom of the tank. I would start there.

 

[fro10987]

see post #9. The fuel cap must allow the tank top vent properly otherwise it will cause a vaccum which will restict the fuel greatly and once you put a vaccum like that on it it can crack the plastic lines that are still in the system. Easy fix try running with the cap off or loose. When you take the cap off you should have a very minor vaccum sound that last a short second. a new cap is only about $10.00 from autozone or shove a rag in it for a trip down the road. If its erratic like you say that would make more sense than a cracked line, unless you drive the same route prety much everyday with stops in the same point. when the fuel is shaken and heated from the daytime it will expand and when it cools it will contract which would cause it to draw from the engine bay causing the hard starts in the AM. next time it does it try removing the fuel cap and restarting. AMke sure you post so anyone else with this problem benfits ..

 

[illflem]

Definitely running out of fuel.
I'd start here http://www.cumminsforum.com/forum/94-98-tech-articles/137589-check-fuel-pressure-12-valve.html

 

[Dodge789]

If you guys have any idea what my truck is doing please let me know. It has done this for about a year now and it is very random about doing it. It might be fine for two months and all the sudden it will do it for a few days and then back to normal. Watch the video and tell me what you think... :thumbsup: Startup001.flv video by DieselRacer75 - Photobucket

I can not help you. I do not have a headset should i do not understand what is going on. :confused013:

 

[ykdave]

Well i cant really do a test on it because it's so random about doing this. when i posted this about a week ago it was doing it every day.. Now it has completely stopped.... But I'm going to look at the lines as soon as I can. One other thang. Every time I pull my gas cap off there is CRAZY amounts of vacuum in the tank. Its like my cap isn't venting. Could that have any thing to do with it?? I know it sounds stupid but my dirt bike wont run if you plug off the gas cap. So is it the same for my truck?

Sounds like your vent line on the tank is plugged or kinked up.

Their should not be any vac in the tank at all, that is likely your problem. try running around with the cap loose so that it will vent and see what happens

 

[DieselRacer75]

Ok... I will check the vent line on my tank. I will also just keep my gas cap loose. I have been letting the the vacuum out of the tank before I start it the past two day's and so far so good.... I tell y'all if this fixes it I will be amazed at the power of a gas cap.....