2001 2500 starting issue

[Daveb]

Hey guys, did a little searching online and found this website. Maybe someone on here can help. Lately my truck has been making a hissing sound coming from somewhere around the sending unit/fuel lines. When it hisses, the truck cranks over about 10 seconds before it starts, like it's not getting any fuel. 

 

The airdog always runs 15 psi. The truck will always start right up within about 15 minutes of shutting it off. But if I let it sit for a few hours, it may or may not start right up. It also seems like this hissing sounds is related to starting. More of a hiss, the harder the start. Maybe I'm thinking too far into it. Has anyone ever seen this before?

[Mopar1973Man]

The first question have you checked to see if the hissing of the fuel tank is vacuum or pressure related to the fuel tank? If its vacuum your tank vent is most likely plugged with mud and debris. If its pressure than you might have bigger issues like a cracked head. So before I scare you to death with what if's let's check and see if there is a blast of pressure when you release the fuel cap or sudden rush of air into the tank because of vacuum. 

[Daveb]

Well, I just drove it around town. Got home. Instantly pulled fuel cap and nothing. No push or pull. It's now starting to get intermittent. I swear it was under pressure last time I did that and it was hissing. It also was leaking fuel too. Granted I only drove for 10 minutes but that's been enough before. I guess I'll try again tomorrow. 

 

Is there a way to check the rollover valve? I mean this truck has 250k and is like 8 out of ten. I baby this thing since I got it, it looked stock before. No oil leaks. Starts up no issue in negative 15 Fahrenheit weather. I retorqed the head too for the heck of it. Got MAYBE an eighth of a turn on SOME of them. They are all now at 123 foot pounds. 

 

It barely EVER hits 1200 degrees. Only for a short tap once in a while. Usually cruises around at 600. Never given me issues till now. 

[Mopar1973Man]

2 minutes ago, Daveb said:

I swear it was under pressure last time I did that and it was hissing.

 

Typically pressure is caused by a cracked head that is cracked into the return rail. So compression gases are pushed into the fuel tank. I really hoping not to be this. I'm hoping for vacuum hiss.

 

3 minutes ago, Daveb said:

Is there a way to check the rollover valve?

 

Typically you would remove the sender or remove the bed so you can work on the sender. I would use some brake cleaner and attempt to blow the vent clear. Bad part is this will push the dirt into the tank. I would rather remove the whole fuel sender and use compressed air to blow it out. 

 

[Daveb]

Hello there, so all day yesterday there was no pressure either direction from the fuel cap. It started right up at 22f outside with no issues after sitting all night. Drive it ten minutes. Shut off. Started back up perfectly. Drove home. Shut off. Three hours later started back up perfectly. Drove 20 mins. Shut off. Started back up. Shut off.  20 minutes later again and it started right up. 

 

This morning. Had issues starting up again. Drove ten minutes, shut off and heard the hiss again. It was windy outside so I couldn't tell if it sucked in or blew out when I loosed the cap. But there was a gasp of air. An hour later, it started right up!!!!! Erg this is annoying. 

 

To be honest, the issue only started happening when it started getting really cold. So it seemed that it was rubber contracting and leaking air? But then it was 50 out for a couple days and did it too so?? However, that doesn't explain the seemingly random perfect starts such as yesterday morning at 22f. It also started fine last week at random in 12f. 

 

 

[Mopar1973Man]

I'm going to run on the hunch that its a vacuum your fighting. So I would say the vent on the top of the sender is plugging up with mud or ice causing the problem. Typically a cracked head would produce a consistent failure in a short time not like your seeing where it comes and goes.  

 

Do you happen to have a fuel pressure gauge hooked up?

[Daveb]

Thanks for the reply. I do. It's saying I'm getting 15 psi. The other thing is when I got the airdog, it said I was running 19. I adjusted the airdog spring to knock it back to 15. 

 

I blasted out the overflow valve yesterday. It was very dirty and MAY have had ice. 

 

The vp is brand new. Literally. And the overflow valve on the return is too. Second vp, second valve. No change to the issue. I had exposed wires on the other one (had 16k) so I had them fix under warranty a couple weeks ago. Could the airdog valve be leaking off?  When I took the little rubber ball out to adjust the spring I noticed that there was already a little ring on it from being pushed into the housing. It's only been on for a year. 

 

The other thing i noticed was that when this all started, the truck at first was flooding during starting. White creamy smoke with airdog at 19 psi. Although it ran fine all summer at 19. I adjusted the airdog to 15 psi, and now no smoke but still lots of cranking. 

 

One last thing you should know is that when I gas hard, the engine wants to die afterwards if I don't give it a little fuel for a couple seconds. Like there's no recovery from a hard pull. Do you think it could have anything to do with MAP or crank sensor?

 

Thanks again for the help. 

[Mopar1973Man]

What is the cranking pressure? Running pressures are fine. 

[Daveb]

I do not yet know. The gague says 15 from the second the cranking starts. But that's not an analog gague running off the fuel psi port. I'd rather check with a shop gague.  It started up fine today. This is the first time I drove it since cleaning the breather last night. Let's see what happens. 

[trreed]

How is your AirDog wired in?  Is it wired to the ECM lead through a relay? Or is it wired to a key on power source?

[Daveb]

I did it per the instructions. Been a while. Lol. It has a relay and bit as for connecting to the truck simply runs off the alternator wires and then the plug for the stock lift pump if I remember correctly. 

*but as for connecting to the truck. 

[trreed]

The ECM will control voltage to the pump while cranking to lower pressures, so it's odd that you're having full pressure right away.

[Daveb]

Well I mean as soon as you bump the starter to get the lift pump going the gauge says 15. Then if you crank it it still has the issue. What I will say though is it has started fine today three times. Let's see how tomorrow goes.  It's never ran fine two days in a row since the issue started but last night I cleaned the breather and this is Michigan so it got down to -20 a couple times and has been mostly below freezing since December. 

[Mopar1973Man]

1 minute ago, Daveb said:

Well I mean as soon as you bump the starter to get the lift pump going the gauge says 15.

 

All truck will supply constant power to the lift pump on a starter bump that is part of the programming. 

 

What happens during your long cranking events what is the fuel pressure showing? Is it bouncing and showing 7-12 PSI or what? It should be bouncing. 

 

 

[Daveb]

I will look closer tomorrow. It's been a few weeks since I checked that part of it. 

[Mopar1973Man]

Let us know. 

[Daveb]

I will look closer tomorrow. It's been a few weeks since I checked that part of it. 

[Daveb]

Sorry didn't mean to send that. So I bumped the key and it went to 15 psi and stayed there while cranking too. And then during starting. 

 

I think that the issue has been resolved though. It has started the last two days and this morning as well didn't even turn over

for half a second before it started. Lol stupid dodge. Always something simple. Gotta love em. 

 

While the post is open, ever since I put the comp on the truck, if you are over about 2k rpm and are pulling pretty hard and instantly let off, it will die. If you slowly let off, it will run on a few cylinders, if you keep your foot on the throttle just a little bit till it goes to idle, it's fine. Maybe MAP sensor?

[Mopar1973Man]

Could you fill in your signature with your modifications and year and model of truck?

 

What's your fuel pressure like during this stalling moment?

 

What kind of boost pressure are you seeing?

 

How many miles are on your injectors? 

[Daveb]

14-15psi

 

sometimes drops to 11 then instantly picks back up to 14 while cruising around. 

 

32 psi boost pressure. Strangely enough 32 psi with stock turbo too. Didn't change when I added 64mm silver bullet or the 120 injectors. Definitely feel more power though. I wonder if it's truly hitting 500+hp. 

 

So apart from stock it's a six speed with a standard comp, 5 inch turbo back with hx 40 downpipe (so 4 inch), 120 injectors, and a 64mm silver bullet. The injectors and the silver bullet have been on since nov. the turbo hardley ever gets lit. Too much for a 6 speed. I just put this thing to work and back in town. Looking for a decent used 62mm or stock one to put back on to make the move to Utah. Gonna put the silver bullet on my built auto when I get it. 

 

 

Not sure about the injector miles. Pulled them from another truck with blown head gasket. Seems to idle super smooth and clean. The box for the injectors was still in the truck so I'm guessing not super high miles. Plus the fact that truck was working fine for over a month with no changes in mods points to something else...  

 

it seems to be good now after blasting out the breather.