Jump to content

New to Cummins, need some possible fuel diagnostics


Recommended Posts

My truck has been dead for a few days now and I was referred to this site for better, more useful help, so here goes... I was in the middle of a coolant flush, heater on full blast, truck was idling for maybe 20 minutes, then suddenly sputtered and died. It cranks but will not fire up. Throws a P0234 code for "overboost", however this seems to be irrelevant, as I was driving it unusually hard the night before, to check for oil leaks since I had just changed oil/filter. Anyways, the issue seems to be narrowed down to lift or injector pump, or both. Heres what I've done so far: added 5 gallons to fuel tank, primed pump 8 times, loosened injector line on one of cylinders while cranking and got some fuel to come out. However, even after priming pump, fuel canister is near empty, pointing towards LP. The next issue is figuring out how much, if any, damage is done to VP since this truck has 200k with no service records and I've only owned it 3 weeks. I've been directed toward 2 bluechip articles regarding some testing procedures that I will get to. I was referred here for some extra help and advice without the "pissing matches" on who's right or wrong.Also, when I crank the truck for say... 5 seconds straight, and let the key go, the pump whines pretty loud under me until I pull the key off. Not sure what means, obviously, even though it's making noise, it can't be pumping fuel can it? My canister would be full, but only has maybe an inch of fuel in it. It's a little late to go out and test anything now, but please share any info you might have for me in the meantime. Thanks guys

Link to comment
Share on other sites

  • Replies 101
  • Created
  • Last Reply

Top Posters In This Topic

  • Administrator

Ouch... I'm going to have to assume the lift pump is dead and so is the VP44. Being that the truck is not starting or running I would would consider getting a lift pump first. While your at it get a fuel pressure gauge and install it. Maybe the injection pump might come back to life with a good strong lift pump. But I kind of doubt it.

For good VP44 life span the fuel pressure should never drop below 14 PSI at WOT on the highway. So if the lift pump is making grinding noises and the filter housing is not filling up I'm going to have to say the lift pump is dead.

But now you said you cracked the lines on the VP44 and tried priming it. Now did the fuel just leak out or was it FORCED out with pressure? You have to remember the VP44 has to create at least 4,500 PSI to first the injectors. so if it just dribbling out its not pumping at all. But if its squirting out and hitting the hood the pump is functional. This also depends on how loose the line is. I normal loose then reseat the nut with my fingers before I start cranking this will typically allow the VP44 build enough pressure to fire all six injectors but squirt fuel up so you can see it.

There isn't enough prove to absolutely pont the finger at both yet condemning them as dead...

  • Like 1
Link to comment
Share on other sites

This is kind of what I was worried about. When I cracked the injector line, I loosened the nut on the first cylinder at the front of the engine. I couldn't see it while cranking, but fuel was just laying underneath it, so I'm assuming it just of dribbled out. I believe I loosened it completely, then finger tighted it just to where it resisted, so pressure should have been able to build up. The truck has glowshift gauges on it now, but I've been told they are junk. Since I owned the truck, the FP gauge went through the roof. Goes straight to 30psi (which is the maxxing the needle) and stays there, but would occasionally dip down to maybe 15-20psi for like 2 seonds while driving.

Link to comment
Share on other sites

I had a Glowshift fo my first fuel prssesure gauge and it did the same thing as yours. Worked fine for a while and then just pegged out. The sender got beat to death by the VP. I did not have it installed with anything to isolate it from the water hammer affect of the vp pulsing. Mike has a good article about this but I cant seem to find it. Hopefully he will help us with that. I have a new Isspro connected thru a needle vavle to isolate it form this and it is working fine. Replacing the lift pump will be a good idea and hopefully the VP will come back. When my lift pump went, the vp lasted another 70k miles. That is not always the case but there is hope.Welcome to the family, by the way.If you go to the user cp and fill out your signature with the info on your truck it will help in the future.

Link to comment
Share on other sites

I had a Glowshift fo my first fuel prssesure gauge and it did the same thing as yours. Worked fine for a while and then just pegged out. The sender got beat to death by the VP. I did not have it installed with anything to isolate it from the water hammer affect of the vp pulsing. Mike has a good article about this but I cant seem to find it. Hopefully he will help us with that. I have a new Isspro connected thru a needle vavle to isolate it form this and it is working fine. Replacing the lift pump will be a good idea and hopefully the VP will come back. When my lift pump went, the vp lasted another 70k miles. That is not always the case but there is hope. Welcome to the family, by the way. If you go to the user cp and fill out your signature with the info on your truck it will help in the future.

Thanks man. Guys, as far as this fuel issue is concerned now, I've made a decision on it. Rather than do all kinds of diagnostic tests, I'm going to suck it up and replace both pumps with quality, dependable ones. I'll put my tax return to good use and swallow my pride. Since the truck has 200k, I don't want to just replace the LP and "hope" the VP will come back and stay up for a while. Who knows when it will go or where I'll be, I'd rather feel safe than sorry, since I have some plans on traveling to Pitt this year, I want the least possibility to get stranded somewhere. Which brings us to the next part of the thread which pump combo to go with? Future plans include: AEM intake, Edge Juice w/Attitude, slightly larger injectors (maybe 50's) and a slightly upgraded turbo. And just to clarify, I plan on driving around with mileage tune, not high power levels ALL the time. Better turbo simple to handle the power without failures. Any suggestions a good setup? Preferably something I can order tonight and have it overnighted, so I can knock this thing out this weekend. Also looking for something that is direct bolt on replacement, I don't want want to have to mess with any new setups. Thanks
Link to comment
Share on other sites

  • Administrator

Which brings us to the next part of the thread which pump combo to go with? Future plans include: AEM intake, Edge Juice w/Attitude, slightly larger injectors (maybe 50's) and a slightly upgraded turbo. And just to clarify, I plan on driving around with mileage tune, not high power levels ALL the time. Better turbo simple to handle the power without failures. Any suggestions a good setup? Preferably something I can order tonight and have it overnighted, so I can knock this thing out this weekend. Also looking for something that is direct bolt on replacement, I don't want want to have to mess with any new setups. Thanks

Something to take notice of... Like on my truck I'm running a Edge Comp with the VP44 tapped and left it set on 5x5 (kill mode). I get awesome MPG in the 21-22 MPG range and high mark of 25.3 MPG for the record. Now as for cold air intakes as we are learning that there is a limit of how cold is good. I'm finding 60-100*F outside temps are goodd for MPG's be below this the IAT temp fall to low to give good MPG's. Bigger turbo isn't really required at all since your not going to be driving with your foot mashed like my turck the stock Hx35 is plenty...
Link to comment
Share on other sites

Something to take notice of... Like on my truck I'm running a Edge Comp with the VP44 tapped and left it set on 5x5 (kill mode). I get awesome MPG in the 21-22 MPG range and high mark of 25.3 MPG for the record. Now as for cold air intakes as we are learning that there is a limit of how cold is good. I'm finding 60-100*F outside temps are goodd for MPG's be below this the IAT temp fall to low to give good MPG's. Bigger turbo isn't really required at all since your not going to be driving with your foot mashed like my turck the stock Hx35 is plenty...

Thanks for the tips. Probably will save a pretty penny on the turbo then. I'm looking at dieselautopower.com right now. They have the Bosch VP44 combo with my choice of stock, DDRP, FRRP, Raptor, or Airdog with some pretty sweet savings.

--- Update to the previous post...

Welp, I'm about to do it... VP44, AirDog150 and a fluidampr, since my stock one is shot. Grand total... $1858 :cry:
Link to comment
Share on other sites

Quick check is to get some starting fluid. Spray a bit of that in the intake and if it fires, then its the VP or LP. If it does not then look elsewhere... Joe

I'm almost 100% positive on the LP... priming it 8 times on Sunday, not to mention all the cranking I've done since then, and STILL barely an inch of fuel sitting in the canister? The only question now is the VP, but a new one is on it's way, so I'm going to wait until all these parts are installed before doing anything else. Hell, if the truck still doesn't start after all this, at least I can be sure my fuel system is pretty damn solid for a while lol.
Link to comment
Share on other sites

Sounds like you are well on your way. You might want to run you some 2 cycle oil in your fuel and help keep that new VP lubed and happy.

I actually put some DieselKleen+cetane boost in the tank when it got just over 1/4 tank since I was planning on filling it up soon, however I never got that far obviously lol. At least I know the fuel going through the new pumps will be clean and stabilized. The Hess is maybe a mile or so down the road from me, so it will be getting a full tank shortly after it's started.
Link to comment
Share on other sites

The diesel kleen actually does the opposite of 2 cylce oil and is harder on the VP. I am going to need the expert on this to chime in with the info to explain it. I used DK for a while but never saw any benifit from it. Cetane booster actually takes away from the btu content of the fuel. I have a grasp of this but some of the other folks can explain it alot better than I.

Link to comment
Share on other sites

  • Administrator

The diesel kleen actually does the opposite of 2 cylce oil and is harder on the VP. I am going to need the expert on this to chime in with the info to explain it. I used DK for a while but never saw any benifit from it. Cetane booster actually takes away from the btu content of the fuel. I have a grasp of this but some of the other folks can explain it alot better than I.

Hit the nail on the head though... :smart: Just make it simple...Here is the cetane page to explain it... This explain both cetane and BTU's http://articles.mopar1973man.com/general-cummins/36-fuel-system/67-diesel-fuel-cetane-rating-and-the-effects Then here is the page explaining fuel additives... The explains the impact of injector cleaners and other fuel additives on the fuel system... http://articles.mopar1973man.com/general-cummins/36-fuel-system/68-hfrr-testing-of-common-diesel-fuel-additives
Link to comment
Share on other sites

Holy crap, so I probably accelerated the damage to my pumps by pouring in such a concentrated dose without filling the tank up along with it. Live and learn I suppose... I guess I will dilute the tank ASAP then before running it through the new pumps. On a side note, I gotta give dieselautopower a shout out here, I had ordered the AirDog 150, knowing it was going to be overkill for my application. However I did not know that I had to drop the tank to install it. Jason called me and verified my order and explained to me the situation to be sure it was what I wanted. So I changed my order to an AirDog 100 and he saved me a BIG headache on the install. I highly recommend anyone with pump problems to check them out, I will be using them in the future.

Link to comment
Share on other sites

I've been looking around at installs of the AirDog 100 that I have on the way. I'm installing mine to the factory fuel sending unit on top of the tank. It is supposed to be a pretty straighforward install, no tank dropping, no drilling, but some people were saying that it was not so. It got me wondering about my install, anyone that has installed one before, could you let me know how it went, or link me to some good instructions. I don't want to have any of these "issues" when I get to a 1/4 tank that I've been reading about. Any install advice is welcome. Thanks

Link to comment
Share on other sites

  • Administrator

Personally I would just do a drawstraw into the tank and not the sender can. I really don't have the 1/4 tank issue unless I'm driving like I stole it. But if I drive like a human being I can run it down to the empty mark without any problems.post-2-13869818642_thumb.jpgOnly a quarter (coin) will fit between the tip and the bottom of the tank. Absolutely no no problems here...post-2-138698186425_thumb.jpg

Link to comment
Share on other sites

So is the drawstraw what is causing most of the issues? People who do it themselves just don't install it low enough or something? I didn't order a drawstraw, but I also never run the tank below an 1/8, I typically wait for the gas light to come on since that means you still have a good 8-9 in the tank. But that was in my V10, I only got a chance to run this truck down to about a 1/4 before the pumps went out.

Link to comment
Share on other sites

  • Administrator

A lot of people cut them way too short affraid of the straw sucking to the bottom of the tank. But actually its the reverse as the tank is filled diesel weighs about 6.1 pounds per gallon so the bottom of the tank deflects another 3/8 of a inch and now with a overly short drawstraw a simple sloosh action will give the 1/4 tank issue. Since my drawstraw is cut so close the tank will pull up tight ot the straw as the fuel level drops preventing the 1/4 tank issues as much. Also don't cut the tip at a 45* anlge must be FLAT! You may notch the tip but only 1/16 to 1/8" deep that's all.Don't get me wrong I can still see quarter tank issue but I understand what causes it... This video was shot at about a 1/4 tank...(2:53 is where it falls) :rolleyes:

http://www.youtube.com/watch?v=grl72Up-8T0

Link to comment
Share on other sites

×
×
  • Create New...