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Discussion Starter #1
Gentlemen (and ladies?) i Could really use someones help here. First let me explain the truck, it’s a 2007 chassis with a 2012 front clip upgrade and an 02 24v that is totally stock besides for an edge tuner with (supposedly 120k), the motor runs great with no blowby. I got it for myself as a birthday present in July and for the first couple of months it’s been great, I changed the oil, all filters, water pump, tensioner, belt. I’ve been really easy on the truck.
the starting process for the truck is (always)as follows; hop in the truck, turn the key three quarter ways which wI’ll let the air dog prime constantly for 15 seconds until it beeps, than it’s ready to turn on and it starts first crank when the engine is cold. (The "prime timer" is set off by time not some sort of prime completion switch). Bear in mind this is all when it’s cold. It starts right up and with the exception of being loud because of course it’s straight piped from the turbo back It runs smoothly.
now the problem: whenever the engine is warm usually over 100 degrees it will prime as normal but when I turn the key it;l just crank forever and never turn on. Upon further investigation I found that the air dog pumps right at spec but seems to have power cut whenever I turn the key to run. I can even feel the relay click but it’s such a mess of wires I can’t seem to locate where they run to. ALSO sometimes it’ll stumble or even cut Out but that is very infrequent.

is this characteristic of some issue? If I put the air dog on another switch and just let it run will It work?

i know it’s long but I wanted to put all the info out there. I appreciate any clues/ help it will save me a lot of money and headache. THANK YOU
912818
 

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The timer is for the grid heaters not the "prime" It does run the lift pump but is not needed to start. It does not even need fresh prime to start and pressure should be under about 17-20 lb. If over that whe hot it actually ahs avalvethat shuts of f fuel. that likely your problem. The lift pump is supposed to shut off when the key goes to start. What is the pressure when starting. I bet over near 20lb.
 

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Discussion Starter #3
Than what is the connection between the grid heater and starting the truck? Because it won’t / wouldn’t ever run without waiting for that beep?
It’s supposed to be able to run with only a small push from the lift pump? Because I think I see some sort of check valve, maybe it’s failed? If I were to put one in than it would hold the prime and once the truck starts up the lift pump will resume?
Again I appreciate the help
 

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The fuels system isclosed and should never have air in the lines of VP unless there is an air leak problem. The fuel is in there and instantly sent to the injectors to start and run the motor. Turning the key to/through ON to start gives the 25 second lift pump shot anyway and then takes back over poweing the lift pump when you let the key back to RUN. When key is in start position a lot of other things are turned off to direct all power to the starter. In warm weather above 40* you shound not even have to wait for the grid heaters (WTS ) light off or anythign else, Just turn to start just like gas. They ALL shlould fire on first cylinder. It should start fine in warm temps or after running without ever waiting for the WTS light to go off or Beep. Don't think anything is different on 02 compared to my 99.
 

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Discussion Starter #5
Okay so it’s great to know that it’s normal for the lift pump to shut itself off when starting. Why else do you think it can be giving me this issue? I would expect it to be easier to start when it’s warm. And on top of it all it’ll start with some starting fluid. Is it possible that fuel isn’t staying up by the VP? Someone I spoke to said I might want to put in a check valve by the VP....
is the computer on the VP just going out?
I don’t see what else can be holding the engine up from starting?
 

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Above 40* it should start easy hot o cold. No you do not need any check valves or other mods.
What codes are you getting?
I kind of expect one of tow things, Fuel pressure over about 18lb when hot or you have and circuit board issue some original VP44's got where after so many heat cycles some of the solder connections become loose. When it gets warm it fails to work correctly due to bad connections. That, I suspect is your problem if fuel pressure is not over 18-20 when hot, especially if you have any code for the VP.
 

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Discussion Starter #7
Sorry for the delay- the airdogg makes more of a buzz and is a little loud, I don’t know anyone else with a diesel so I’m not sure if that’s normal.
I’m guessing it’s the vp from what I’m reading but does it make sense that symptoms are so inconsistent? I’d like to determine that it’s definitely it before I take the leap into buying a new one... is their a way of doing that?
Also I can’t read any codes because it’s a swap and it only retains the factory obd2 with a bunch of Ford error codes.
 

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Discussion Starter #8
The truck surges sometimes when it’s coldish and I come to a stop, is that a symptom of a bad vp?
 

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We need fuel pressue before we can say any more about what it is. Don't jump to VP yet.
 

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Discussion Starter #11
It jumps up and stays there, after 5 minutes of running it Fluctuates about 2psi. Just shakes up and down basically
 

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That should not be too much for the valve in the VP. Do you know exactly when it will happen and when not? So yo do not have the OBD plug hooked up? What is the PN on the ECM? Do you have a working WTS light?

If you are into taking it to a shop, Ford used to use our same Cummins in their Medium duty trucks F650 and 750. I would find one of the Commercial Medium Duty Ford dealers and see if their shop can diagnose it for you in an hour or tow.

Other than that internal fuel valve issue with too much pressure shutting it off the only heat rrelated VP issue I am aware of is in both older VP44's adn original ECM's there was a problem with "heat Cycles " on the circuit boards in them where the solder connections would come loose from the heat cycles and bad solder of the 1990's. When they get hot they would loose connection or have too high of resistance to work.
That could be your issue.
You do not have another VP or ECM you can swap out for a test do you?
 

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Discussion Starter #14
Theirs no issue that’s absolutely bound to happen which I find so weird. The biggest and most common ones are not starting after it has warmed up, it’ll shut off the lift pump when starting as you know but will start with some starting fluid. Other than that it might surge or skip after a while and sometimes it goes dead completely and other times it’ll run flawlessly
The ford obd gives me a bunch of open circuit codes but non that relate to the 5.9 at least i think. No wts light but their is a timer that makes a beep from inside the dash but I can’t tell if it’s aftermarket or not.
the heat cycle thing seems to make sense I’d just rather be sure you know, it’s kind of a big expense to take a guess on.
once again thank you for your time
 

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Other than the fuel pressure issue and Heat cycles circuit board issues have no idea. Unless you can figure a way to pull codes I have no idea other than parts swapping, I hate having to buy $1000 parts for that.
Search hot start issues here and Google.
See if you can fnd somethign at Mopar1973man wesite, Join. He/they is really good, Get back when solved.
 

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They are not readily availble dn almost as expensive as the whole thing w/o warranty. Shopw wiht the Bocsch machine can but is is difficult for your orm e without experience and the tools. Where do you live? Do you have a Diesel Injection shop near your?
 

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Discussion Starter #18
No one can say for certain but do you think a new VP you would be a safe bet?
I live in Long Island NYand I’ve been looking everywhere but I can’t seem to find a decent place to do the work. I even stormed outside the cummins distributor and paid one of their techs to come to my house but he never showed.
would you happen to know of anywhere?
 

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Try this one or use Google for others in your area. Don't be afraid to drive a couple of hours for walk in service/test.

 

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Discussion Starter #20
Yea I’d always rather drive for good service- they’ll be able to test the vp for me? Pressures? Or the circuitry?
 
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