| Author | Message | ||
| James Robinson (Jjrbus)
Registered Member Username: Jjrbus Post Number: 180 Registered: 12-2000 Posted From: 174.150.86.101 Rating: N/A |
Would the fuel level in the tank have much affect on the operating tempature of the injectors? Would it be an issue? | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 371 Registered: 3-2007 Posted From: 71.55.230.210  Rating: N/A |
JR; fuel level in the tank would have nothing to do with operating temp of the injectors. they are efected only by the water temp of the engine. What issues are you having? You may need to go a little deeper explaining your problem. Gomer | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 602 Registered: 8-2006 Posted From: 74.33.35.55 Rating: |
James, Gomer is a little off on fuel cooling keep your tank close to full and it is not a major problem, fuel is returned to the tank at around 150 degrees.I have a fuel cooler on my 8v92 and my Chevy pickup has one the hotter the fuel becomes you will have a hp decrease.Fuel coolers have been used on DD for years in the marine world.Trucks use aluminum tanks mounted on the sides to help with fuel cooling something a bus doesn't have good luck (Message edited by luvrbus on December 14, 2008) | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 372 Registered: 3-2007 Posted From: 71.55.230.210 Rating: N/A |
luvrbus: where do the fuel get it hots from?? LOL The engine and yes it do get hotter coming back than going to,However I will agree that a cooler is sometimes needed. Now the problem is not been told as why the thread began.. LOL You still have my vote tho. Gomer | ||
| James Robinson (Jjrbus)
Registered Member Username: Jjrbus Post Number: 181 Registered: 12-2000 Posted From: 174.150.86.101 Rating: N/A |
Not haveing an issue. I was reading the fuel gauge thread. It started me thinking that keeping the tank full might be better for the injectors or maybe a non issue?? Just the rambling misfireing's of a expireing mind. | ||
| Mel La Plante (Mel_4104)
Registered Member Username: Mel_4104 Post Number: 100 Registered: 7-2006 Posted From: 64.180.195.100 Rating: |
Marvin you way off when you say that the amount of fuel that you have in the tank does no matter---WRONG--the more fuel that you have in the tank the cooler the injectors will operate as the nose of the injector is where the by passed fuel circulates as it returns to the tank to be mixed with the cool fuel there, the more fuel means cooler fuel to be pumped to the injectors hence cooling them. this nose piece is a heat exchanger, if you take an injector apart you see what i mean, if they get too hot they will sieze up and if it happen in the open position you are in trouble , this over heating is what causes the dropped injector problem. over heating of them is why a good rule of thumb is never run with less than 1/4 tank of fuel, i all ways like to keep it 1/2 full. running with small amounts of fuel in any fuel tank is a no no as it stirs up the crap on the bottom of the tank and raises heck with the fuel pump and this includes gasfuel tanks. | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 317 Registered: 8-2004 Posted From: 68.84.6.177  Rating: N/A |
Mel wrote "Marvin you way off when you say that the amount of fuel that you have in the tank does no matter---WRONG--the more fuel that you have in the tank the cooler the injectors will operate as the nose of the injector is where the by passed fuel circulates as it returns to the tank to be mixed with the cool fuel there, the more fuel means cooler fuel to be pumped to the injectors hence cooling them. this nose piece is a heat exchanger, if you take an injector apart you see what i mean, if they get too hot they will sieze up and if it happen in the open position you are in trouble" __. I can understand that this would happen when a tank is run out and there is basically *no fuel* to circulate and cool things. But is there solid, scientific research that shows there's a difference in fuel temp between 60 gallons of fuel in the tank and 30 (that's fuel temp going into the injector)? I don't know, but my experience (all on light duty stuff) makes me think that it's most unlikely. __. And has any study shown the diffence in fuel temp climbing a grade with 60 gallons in the tank going from Nevada into California at 90 degrees F versus what it is running with 30 gallons across Florida when it's 55 degrees? | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 661 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
I gotta disagree with Gomer also. Return fuel cools the injectors, and if it isn't a DD, the injection pump also. The heated fuel needs a place to give off its heat, and if there isn't much in the tank, not much hot wall space in the tank to give it off. Not much mass to absorb the heat either, so the fuel in a low tank will be really warm. Since almost anything that gets warmer expands, hot fuel has less power, because the molecules are bigger, and less of them get injected per stroke. Many fire trucks wouldn't pass the pump test, because the fuel got hot with the truck standing still pumping away. The solution was as mentioned above, a return fuel cooler, valved on in the summer, off in the winter. When the 99 and 2000 Cummins 5.9 engines lose the delivery pump, the trouble prone VP44 injection pump will suck enough fuel to keep running, then will fail from overtemperature shortly thereafter. Yes I know, they fail anyhow, but it happens sooner when the delivery pump fails. G | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 604 Registered: 8-2006 Posted From: 74.33.35.55 Rating: N/A |
There is a section in my 8v92 manual that tells about the affects over heated fuel and the power you lose after it reaches a certain temp this why I installed a fuel cooler living in AZ | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 373 Registered: 3-2007 Posted From: 71.55.230.210 Rating: N/A |
Ok; The fuel pump picks up the fuel from the tank and delivers it to the injectors, where it delivers the fuel,what isn't used at that time is pushed back to the tank to be reused . Correct? Now the temp will be different coming back to the tank than going to the injectors, right again? As stated above, about 150 degrees. What am I missing? The original question was "would the fuel level have an effect on the operating temp of the injector." At what temp?,under what conditions? Many question can arise from this,I think, However I feel that in hot climate or conditions a cooler is ok and in colder conditions not needed. Also the question was "Would this be an issue" Let's answer that. LOL to ya I need to have this answered too since I live in Florida.. LOL Gomer | ||
| Mel La Plante (Mel_4104)
Registered Member Username: Mel_4104 Post Number: 102 Registered: 7-2006 Posted From: 64.180.195.100 Rating: N/A |
Gomer the best way to answer that question is for you to get a book on physics on metals and look up coefficent of expansion and the soefficent of friction and after studing that for a while you will see how tempature effects different metals. now you will see what happens to the push rod of the injector as the bore is at a different tempature and as they change you will see what happens to the clearance between them at different temp. when the push rod expands greater that the hole of the bore the coefficant of friction becomes 0 and the injector seizes. good luck on your study. or you might like to read the DD manual. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 665 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
The answer to this is pretty simple. We fire up our bus and take off with the tank at ambient temp. As soon as the eng warms up, and we work it a little, the ambient temp fuel is returned at 150 degrees. After a short while, all of the fuel in a low tank will have been thru the eng, and be at 150 minus whatever cooling occurs. What happens when the fuel is now SENT TO THE INJECTORS at more or less 150? Obviously it comes back higher still. Next pass will be higher, until the temp diff is great enough that the loss finally equals the input. Nuff said. G | ||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 1239 Registered: 5-2001 Posted From: 65.74.69.188 Rating: |
I would think that a partially plugged fuel filter would be more of an issue than how much fuel is in the tank. It seems to me that just as the filter plugs to the point that the injectors take most of the pumped fuel, there will be very little cooling of the injectors by excess fuel flow. At that point, the cooling would have to be mostly from the coolant, by way of the copper sleeve. What do you think? Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 667 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
I think that is a pertinent question, and those would be really hot injectors. G | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 600 Registered: 10-2006 Posted From: 66.82.162.10 Rating: N/A |
"There is a section in my 8v92 manual that tells about the affects over heated fuel and the power you lose after it reaches a certain temp this why I installed a fuel cooler living in AZ" The only "loss" would be at full tilt , otherwise the gov will maintain the power level needed by your foot. Full tilt would be harmed by air bubbles in the recirculated fuel and the less dense fuel . The temperatures in compression ignition get so high the only concern is the fuel carrying off enough heat that the fuel in the supply doesn't actually BOIL! FF | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 605 Registered: 8-2006 Posted From: 74.33.35.55 Rating: N/A |
FF read section 2.5.1 in Da Book every 20 degrees over 90 it's states a 2% drop in HP direct from the Book and DD not me | ||
| Tom Christman (Tchristman)
Registered Member Username: Tchristman Post Number: 52 Registered: 1-2006 Posted From: 66.218.33.156 Rating: N/A |
When Detroit came out with DDEC engines, they flowed more fuel and picked up more heat-so much so they installed fuel coolers from the factory. If you drive in hot weather, a fuel cooler will save fuel, keeping the fuel more dense since it will be cooler. Good Luck, TomC | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1431 Registered: 12-2000 Posted From: 76.68.121.23  Rating: |
Again, the theories are correct, but in what proportion? Hot fuel has less power, but will the cost of a fuel cooler be recouped in the fuel saved? I'm doubting... While thinking about hot fuel, I'd be thinking Americans best raise Cain about the hot fuel issue at the pump, and how those from the States that do not regulate these matters are being ripped off $$$$ by being sold hot fuel using volume measure. happy coaching! buswarrior | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 608 Registered: 8-2006 Posted From: 74.33.35.55 Rating: N/A |
BW, the cooler was less than a 100 bucks worth a try for me,I am pleased with the results so far you would think a 8v92 wouldn't return any fuel to the tank as they love the stuff good luck | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 320 Registered: 8-2004 Posted From: 68.84.6.177 Rating: N/A |
Bw wrote "Again, the theories are correct, but in what proportion? (snip) I'm doubting... " As I wrote above, where is the data to show that there is any real damage to be done by running any practical level of fuel? Is there any data (sorry, a statement "all the old truckers know" doesn't cut it) to show that there's any difference in the temperature in fuel injectors between a tank half-full and a quarter-full (under the same conditions of speed, air temp, etc.)? And, if there is, is there any data to show that the hottest temps you'll see are in the danger area for damaging injectors? It may be that the worst case (low fuel level, hot temps, hard engine use/hill climbing, etc.) *is* in the area where injectors will coke up but I want to solid data. In the absence, it's an old wive's tale. | ||
| Mel La Plante (Mel_4104)
Registered Member Username: Mel_4104 Post Number: 105 Registered: 7-2006 Posted From: 64.180.195.100 Rating: N/A |
Bruce the data that you want is at any DD dealers just go to their accounting department and ask to see the bills related to low - hot fuel, they will have them. by the look of your MO it shows a plane does it mean that old piolets do not know any thing about them,are they as you stated like old truckers or is their knowledge fall in the place --just doesn't cut it. here on the BNO we try to pass on what little we may have learned over the years whether from book or hands on and are always offer to help anyone that may be broke down on the side of the road, and i have never had one ask to see my books. but they have all said thanks.so you might want to tell people real quick who you are so they will not waste you time as it is doutfull if they will have a referance book with them, but good luck any way. | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 374 Registered: 3-2007 Posted From: 71.55.230.210 Rating: N/A |
I quit this thread LOL IT is getting off beat. Gomer | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 604 Registered: 10-2006 Posted From: 66.82.9.57 Rating: N/A |
AS a boater I worry far more about OLD fuel than hot fuel. We have sucessfully run (with a good log) till the tank took 125G on refill, into the Sportscar. Not much left of the old stuff then. The con at the fuel islands is the company purchases fuel at 55 F , underground temp , and then sells the fuel , after sitting a shiny truck in the sun for 2 days , to you by the gallon, which is a measure of VOLUME. Profit a couple of percent to them for free , Flying J is the biggest offender. When we have purchases the fuel , weather its hot or not doesn't make a difference , except at 100% full load. The gov will let the proper number of fuel molicules , to produce the power your demanding , weather the fuel is thin & hot . At full tilt any reduction in fuel density might be noticed , but if big oversized defuller injectors are installed , and you stream black , smoke you are still overfuled , and will not have the power desired , hot or cold fuel. FF |
