Truck starts and dies repeatedly

2002nightmare

2002nightmare

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Jul 1, 2011
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133
Upon completion of having the head rebuilt, 115# valve springs, 188/220 Cam, extreme duty pushrods, 7 x .012" injectors I'm having what appears to be a fueling issue. The Air Dog pump did not have a ground through it's own wiring harness so I cut the ground at the relay and wired it directly to the battery. The truck ran perfectly for about 2 hrs total run time, with several start ups in that time and no issues. Now it dies, starts right back up sometimes and idles fine but eventually dies. Sometimes it starts hard and idles rough before dying again. I have checked and cleaned both grounds and wondering about a cam sensor. I always have a tach signal and no codes whatsoever with a Smarty. Can a cam sensor allow a truck to run and have a tach but still be bad by chance? Also, will the ECM command the lift pump to cycle EVERYTIME the starter is engaged or are there times when it will not cycle even after engaging the starter? There are times when I can not get the Air Dog to run after cycling the key. Electrical gremlins are not my specialty but changing the cam sensor isn't an issue being they are fairly cheap. I just second guess the VP being bad as I had no issues prior and the truck always runs again although sometimes it takes a minute. I should also mention I have a new Timbo APPS already on.


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I've know a few people who have had bad experience with Air dog motors going out, but also know alot of people who have no problems. Maybe yours gets hot after it runs for a little bit then cuts off. I don't know, but just an idea. Try running it and test the volts to the hot wire going into the motor as it runs to see if there's a drop or not.

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Air Dog is brand new as well as filter and separator are brand new. I have a fuel pressure gauge hooked up under the hood and a low pressure warning light. I'm not going to rule it out because this is my third pump in 2 years on this truck, but it doesn't seem like it's the Air Dog at this point.


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When my truck's cam sensor was going bad/was bad my truck would start run fine about half the time. But the other half I would be driving and my tach would fall to 0 and it would be in limp mode. It would also die going down the road and i'd have to throw it in neutral and restart it.
 
From my experience, Airdog and Raptor DO NOT need to cycle every time the key is turned to the on or "bumped"

I recently went through a spell with AIR in my fuel system and thought it weird that in testing various things the Raptor didnt always cycle. It would, then I would shut it down and wait 30 seconds or so and go to bump and it wouldnt, wait a min then it would. So and and so fourth.

Called my mechanic and he said that this is normal. They don't always cycle.

NorCal.

Have you ruled out AIR in the fuel somewhere??? After a larger job like that maybe you are sucking air. Or leaky injector...rough start or hard start IMO and limited knowledge suggests AIR or Injector...
 
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I am not well versed in fuel systems so to speak, but I have good pressure to the VP and a full tank of fuel. Pull the quick disconnect off the VP inlet and I can get more fuel than I can catch. I changed the cam sensor tonight with no good results. Cut the VP plug off another wiring harness, using pin #6 and #7 to replicate the "hot wire test" as Blue Chip describes and the truck runs the same. Hard to start, rough idle and dies. I believe this to rule out any other possibilities so it looks like a Monster pump will be going on this week or next.


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Air in the fuel?

Just because open line flow large amount doesn't mean under working pressure it meets the requirements.

Any error codes currently?
 
I never did have any codes (according to Smarty) and at times the truck would idle for long enough to move the truck to different sides of the shop. Installed a Monster Mike pump 2 weeks ago, and the truck runs exceptional. I haven't had a single issue in almost 600 miles.


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I only have an Autometer mechanical gauge and it holds 15-16psi always. Almost 700 miles with the Monster now and not one issue.


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