Engine/Transmission (1998.5 - 2002) Frustrating hard start condition

[Camp]

Normally it fires right up with a bump of the starter, but I have an intermittent condition where it behaves like it's out of fuel. Then suddenly it's fine for a few days.



The symptoms:

Engine turns over for several seconds (5-10) before it fires, then idles rough for a few more seconds before returning to normal. Otherwise runs and drives just fine. Seems to be aggravated by parking the truck with the nose uphill, although this alone won't guarantee that it'll occur. The condition has appeared when the truck is sitting level, just not as frequently, but it has NEVER occured when the nose is parked downhill. The truck has to sit for a bit for this to happen, but it seems to come in groups. Won't have a problem for weeks then bam, several starts in a row are like it's out of fuel.



The truck:

2002 HO 6spd 2500 w/ 65k miles.



When it started:

First instance was after the dealer replaced the VP44.



What I've done to try and fix this:

• Took it to the dealer several times but they weren't able to replicate it. Again this is an intermittent thing. Once I took it to them nearly empty of fuel because at the time it seemed like it was dependant on the fuel level, but that's not the case. It has happened with nearly a full tank, so a leak in the pickup in the tank is unlikely.
  
• Removed and cleaned the fuel tank vent, although it has never had a vacuum when removing the cap. Worth a shot, but wasn't the problem.
  
• New fuel filter and o-ring. No effect.
  
• Replaced the overflow valve (check valve banjo and washers) on the VP44 return line. No effect
  

Fuel Pressure info:

Since I suspect a fuel starvation problem, here's some info regarding the fuel pressure on startup. When I turn the key on the fuel psi immediately (albeit briefly) goes to about 5psi and then usually drops to zero by the time the "wait to start" light goes out. If it doesn't fire in a couple turns I know it's acting up, so I let off the starter and let the lift pump run. Fuel PSI goes right to 15 psi and I wait a few seconds and try again. Repeat until it fires (usually two or three times with some coughing and sputtering along the way). If I don't let off the starter it takes 5-10 seconds to cough to life which feels like an eternity when I just know that VP44 is turning over dry. Again on a "normal" day I bump the starter and it fires right up, no coughing, no sputtering.



IMO it appears the fuel is draining out of the VP44 when it sits, but why this is intermittent is beyond me. I thought the intermittent behaviour clearly pointed to either the fuel tank vent or the check valve (sometimes it seats, sometimes it doesn't) but I was wrong. I'm at a loss for what to try next. All I can come up with is A) replace all of the fuel lines or B) replace the VP44. Is it possible it's leaking into the engine instead of back to the tank? I've monitored the oil level, it doesn't appear to be changing and it doesn't smell like it's contaminated with fuel. Would a faulty injector cause this?



Help??

 

[JR2]

Here is a shot in the dark, replace the overflow vavle on the VP44. If it was sticking open it would cause the VP44 to loose prime.



To see where it is: http://dodgeram.org/tech/dsl/mt_2_feb98/fuel_sys_comp.htm



Do a search for overflow valve in the 24v engine forum and you should be able to find a part number.

 

[Camp]

Here is a shot in the dark, replace the overflow vavle on the VP44. If it was sticking open it would cause the VP44 to loose prime.



To see where it is: http://dodgeram.org/tech/dsl/mt_2_feb98/fuel_sys_comp.htm



Do a search for overflow valve in the 24v engine forum and you should be able to find a part number.

Sorry, I didn't realize it was called an overflow valve, I just called it a check valve. I replaced that this weekend (last bullet in the above list) and the problem still exists Thanks for the suggestion though!

 

[Camp]

Well at least I'm not the only one stumped by this. It seems I have no choice but to take it in for service once again and hope that this time they can replicate and repair the problem.

 

[Bob Wagner]

Truck is bone stock? no modifications at all?

 

[Camp]

Truck is bone stock? no modifications at all?

Bone stock fuel system except for the fuel pressure gauge (using the tapped banjo from Geno's at the filter outlet). Other mods are K&N filter, 4" exhaust, and TTPM (problem exists with or without the TTPM). Everything else is stock.



This problem showed up within a week after the VP44 was replaced (216 code, would briefly lose power under load). First they replaced the lift pump but the sudden loss of power still happened, then they replaced the VP44 which cured the problem, but then the intermittent hard start condition appeared. The replacement lift pump died an early death (within 2 weeks) so I was hopeful that was the problem, but a replacement lift pump (3rd one now) did not cure it. I have to think it has something to do with the VP44 replacement (either the procedure or the unit itself), that's such a suspicious coincidence.

 

[Hohn]

Normally it fires right up with a bump of the starter, but I have an intermittent condition where it behaves like it's out of fuel. Then suddenly it's fine for a few days.



The symptoms:

Engine turns over for several seconds (5-10) before it fires, then idles rough for a few more seconds before returning to normal. Otherwise runs and drives just fine. Seems to be aggravated by parking the truck with the nose uphill, although this alone won't guarantee that it'll occur. The condition has appeared when the truck is sitting level, just not as frequently, but it has NEVER occured when the nose is parked downhill. The truck has to sit for a bit for this to happen, but it seems to come in groups. Won't have a problem for weeks then bam, several starts in a row are like it's out of fuel.



The truck:

2002 HO 6spd 2500 w/ 65k miles.



When it started:

First instance was after the dealer replaced the VP44.



What I've done to try and fix this:

• Took it to the dealer several times but they weren't able to replicate it. Again this is an intermittent thing. Once I took it to them nearly empty of fuel because at the time it seemed like it was dependant on the fuel level, but that's not the case. It has happened with nearly a full tank, so a leak in the pickup in the tank is unlikely.
  
• Removed and cleaned the fuel tank vent, although it has never had a vacuum when removing the cap. Worth a shot, but wasn't the problem.
  
• New fuel filter and o-ring. No effect.
  
• Replaced the check valve banjo (and washers) on the VP44 return line. No effect
  

Fuel Pressure info:

Since I suspect a fuel starvation problem, here's some info regarding the fuel pressure on startup. When I turn the key on the fuel psi immediately (albeit briefly) goes to about 5psi and then usually drops to zero by the time the "wait to start" light goes out. If it doesn't fire in a couple turns I know it's acting up, so I let off the starter and let the lift pump run. Fuel PSI goes right to 15 psi and I wait a few seconds and try again. Repeat until it fires (usually two or three times with some coughing and sputtering along the way). If I don't let off the starter it takes 5-10 seconds to cough to life which feels like an eternity when I just know that VP44 is turning over dry. Again on a "normal" day I bump the starter and it fires right up, no coughing, no sputtering.



IMO it appears the fuel is draining out of the VP44 when it sits, but why this is intermittent is beyond me. I thought the intermittent behaviour clearly pointed to either the fuel tank vent or the check valve (sometimes it seats, sometimes it doesn't) but I was wrong. I'm at a loss for what to try next. All I can come up with is A) replace all of the fuel lines or B) replace the VP44. Is it possible it's leaking into the engine instead of back to the tank? I've monitored the oil level, it doesn't appear to be changing and it doesn't smell like it's contaminated with fuel. Would a faulty injector cause this?



Help??

Camp, I have a lot of empathy for you, as I battled this condition for over a year.



The thing that makes it so hard to diagnose is that one problem can have MANY causes. So, you start throwing parts at it with no help, only to find that the thing that SHOULD have fixed it, didn't. That's because you often have TWO OR MORE causes of the same problem.



In my case, my symptoms were pretty similar. It would fire right up when parked nosedown, but uphill, it had to crank and crank.



I was getting some hissing from the fuel tank, but it wasn't vacuum, it was pressure! Fuel filler cap almost took off my head when it first happened.



So what fixed it for me?



1) I loosened and retightened my injector holddowns and injection line nuts (the 19mm ones that go right into the head). Alternate snugging up the little 8mm holddown bolt and the 19mm injection line nut. The slightest misalignment of the crossover tube at the injector can cause a leak (fuel and/or air) that produces hard starting. Make sure that the crossover tube O-rings have no nicks in them.



2) The fuel return system (whether in the head or outside the engine) seems to be the usual culprit. There is a tee at the back of the engine where the injector return and the VP44 return meet. This can sometimes come loose enough to let air in. I tightened mine down, but didn't notice a difference.



3) Check for loose clamps on the fuel return lines from the tee I mentioned all the way back to the tank module. I had a loose spot where the rubber return line met the hardline (along the framerail) and THIS will let air in, causing a loss of prime and a hard start condition. \\



Ultimately, it was BOTH #1 and #3 that were causing my hard start problems. #3 was the main cause, as the truck would lose prime after it sat. I was basically having to reprime it every time I fired up the truck, and this took a lot of cranking. I fixed #3, but the problem didn't completely go away-- it just went from being constant to being sporadic.



#1 is what made the problem go away completely. I probably had just a slight misalignment in the crossover tubes (I checked them all to see if they were bent and they were straight), and this allowed a little air into the return system.



One thing to keep in mind is that the fuel system on these trucks is one big loop, and a leak anywhere in that loop (whether send OR return) will cause a loss of prime and a hard start condition.



If you have satisfied yourself that there are no fuel leaks ANYWHERE in that fuel loop, then you probably have an air leak letting air in. Air will leak from places that fuel won't.



If you can confirm that there are no air OR fuel leaks at all, whether leaking in or our of the system, then your problem is most likely in the tank.



This was driving me so crazy that I ordered a fuel bulkhead, and AN socketless hose/fittings to bypass the OEM module entirely. Turns out that the problem wasn't the module at all. I still have the bulkhead and hose sitting on the shelf.



Module issues are known, but they seem to be mostly on the earlier trucks, IIRC, not that 01. 5 and 02s.



I would make EXTRA certain that it's not something outside the tank before dropping it. One other thing to be careful of when troubleshooting problems like this-- it's VERY VERY easy to create a separate cause of the same problem while trying to troubleshoot it. You end up fixing what initially caused it only to create a new cause that manifests itself in the exact same way.



Frustrating? Totally. You and a few others are the only ones that can know how I felt. So, work VERy methodically was you trace each link in the fuel system chain and eliminate it as a cause. Start at the external tank fitting for the send side and end at the external tank fitting for the return side. There are MANY links in the chain between those points, and EACH of them is a potential cause.



Hope this helps. PM me if you need more help.



Justin

 

[Camp]

You and a few others are the only ones that can know how I felt.

We're just the lucky ones I guess



Many thanks for the suggestions, I didn't realize it was sensitive to the return line anywhere downstream of the overflow valve. Now that I think about it I remember a small bypass hole in the valve which isn't closed off by the ball, so what you mentioned makes sense. I don't understand why they did that, I'm half tempted to plug the hole on the old check valve and see if that cures it. If so then I know there's a leak downstream somewhere. If it doesn't then the leak must be in the injector lines or the VP44 supply line.



Since it's intermittent, I'm now suspicious of the injector lines. If one of those has a leak I suspect you would only notice it if the pump was in the right position. 5 times out of 6 that line would be sealed via the pump, yes? Since this started only after the VP44 was replaced then surely they removed and reattached those lines (in addition to the supply line). Correct me if I'm wrong, but that sure seems like it fits the scenario and it matches your intermittent experience.



I just dropped off the truck over lunch with the instructions to "replicate the problem and don't call me until you do. " Let me know what you think and I'll give them a call and request that they look specifically at those lines.



Thank you!

 

[Hohn]

The injector lines could be it. It was for me. You have to torque them just so, alternating and such, or they won't seal properly. At least, that was my experience.



I took me more than one re-torque to get it right.



jlh

 

[Lsfarm]

Help the Dealer's Tech

In order for the dealer to reproduce the hard start, have them leave the truck overnight with the front of the truck up on jackstands. Make sure they don't start it every hour or so, but let it sit for 12+ hours. If the fuel tank is low this should demonstrate the problem to them.



It doesn't take much of an air leak to let in enough air to cause hard starting. It isn't the VP loosing prime [usually, this would be a big leak] it is air in the injection lines after the VP. In order to open an injector it takes a lot of pressure [not sure how much but over 3000psi I believe] So if there is air in the line, the air must be compressed down by the very small injection pulses from the VP. The volume of the injection pulse at idle speed for one injector is very small, like 1/10th of a drop. So it takes a lot of these pulses to compress the air in the line enough to raise pressure in the line high enough to get the injector to finally open and bleed out the air. . This is why it takes so long to get a truck running after an injector swap. Bleeding the lines helps, but it still takes a lot of cranking.



You probably have as discussed above a very slight leak at one or more of the injectors, or the cross tubes. If the injection lines have been over torqued they could have damaged sealing seats and need replacement.



Good luck, hope this helps. Greg L

 

[Camp]

Thanks for the additional info Greg!



I picked up the truck on Friday after the dealer claimed they were unable to reproduce the condition. Twice I checked on it, and both times it was parked either level or with the nose downhill despite my explicit description that the problem only occurs with the nose uphill. No wonder it fired right up for them The technician's notes claimed that I had messed with the injection system and wiring harness (both lies ) and suspected the issue was "caused by an aftermarket power up kit". The injection system and wiring harness are 100% stock, there is no "power up kit" on the truck, and yet the problem exists. I replaced the overflow valve at my own expense to rule that out as a possibility, otherwise my contact with the injection system has been limited to changing fuel filters. His comments about the wiring harness are in regard to my removal of his unauthorized modification. He heatshrinked the datalink port on a previous visit, without my authorization, and I had removed that restoring it to the factory configuration. The last thing I want for a truck with a history of problems is heatshrink over a valuable troubleshooting port. It's a sad day when the technician, who is supposed to be helping you fix an issue, becomes part of the problem. This isn't the first issue I've had with these guys either (Prestige Dodge in Longmont, CO), but after two years of exceptionally sub-par "service" it is my last. Based on my past experience with them I should have known it would be a waste of my time.



So I'll have to continue to troubleshoot this and fix it myself. This weekend I replaced the supply lines and banjo bolts with the big fuel line kit from Power by Poole. This made a nice improvement to my WOT fuel pressure (feels great to be rid of all of those banjos!), but the hard start condition is unchanged. Thus the culprit must be downstream. New injectors are on the way (1. 6 EDM's) and I hope to install them tonight, which will leave only the injector lines and the return lines to check next.



Thanks for the help, I'll keep you posted

 

[Lsfarm]

Injector swap

Take the time to very carefully inspect each crosstube for nicks or flaws where the tube seats into the side of the injector, and where the injector line tightens against it. You may find your culprit there.



Also if one or more injectors are really soaked with diesel on the outside then suspect a leaking cross tube.



Good luck hope you find the problem. Greg L

 

[DNolan]

I had the same issue if you have eletric fuel pressure sender it may have a internal leak. mine drove me crazy :{

 

[Camp]

I had the same issue if you have eletric fuel pressure sender it may have a internal leak. mine drove me crazy :{

I do have an electric fuel pressure sender, but I wouldn't expect that type of leak to be intermittent? I'd think that would cause hard starts every time?



Fwiw I installed the new injectors last night and this morning it fired right up. Way too early to tell if I inadvertently cured the hard-start issue due to the intermittent history of the problem, but the new injectors make me smile a little more Thank goodness I got rid of all of those banjos in the fuel supply, because these injectors are still able to pull it down to 8psi WOT. I hate to think what that number would be with banjos (probably 5 psi or so ). Right now the TTPM is set to timing only, I can see already that EGT's will be a little toasty towing at this altitude. Empty I was able to hit 1250°F with 31psi boost. Definitely needs a new clutch and turbo before turning the TTPM fuel settings back on.

 

[Camp]

Update

Just thought I'd share an update on this. I hope I don't jinx myself with this reply, but so far the hard-start condition appears to have been fixed. It's two weeks since I installed the new injectors and it has fired right up every time, even when repeatedly parked with the nose uphill. If it truely is fixed I can't say if the problem was a bad injector or one of the crossover tubes not being seated. I don't know if the previous (and severely inadequate) technician loosened any of these lines when changing the VP, but it wouldn't surprise me. If I had to guess I'd say one of the lines wasn't tightened properly. Bottom line is so far it appears to be fixed



Got the try out the 1. 6's towing over the holiday weekend as well. Towed 7k lbs over the Rockies without any difficulty, most of it in 6th gear (315's and 3. 55 gears make this quite an accomplishment). Basically I'm back to the performance I enjoyed with the 265 tires and the TTPM. I swapped out the K&N cone filter for a BHAF before hitting the road (I still have to fab and install the heat shield btw), and the hottest EGT's in 6th was a steady 1250. 5th gear on the other hand can get hot very quickly, but managable with the throttle. Keeping the EGT's around 1250-1300 resulted in 65-70 mph on any of the passes which I'm happy with (for now).



Thanks to all who offered assistance, hopefully the hard-starts are truely behind me now

 

[Lsfarm]

Good Feeling

It's a good feeling to expect the truck to start instead of wondering if it will!!



Glad to hear it appears to be fixed.



Greg L

 

[Hohn]

Yeah-- now just pray that I don't screw up my good-running truck when I put in my new Don M injectors!!



C'mon Mach 4s!!