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no firing on 5th cylinder

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Old 12-07-2008, 07:14 PM
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no firing on 5th cylinder

Hi I have a 97 with only 71k miles on it and it has had a problem of not firing on the 5th cylinder since I bought it. Initially I thought that it might be a stuck or burnt valve but it has good compression in all cylinders. when I crack the injector lines the engine pitch changes as to be expected on all but the 5th cylinder and it also appears that it does not spurt out of the line like it does on the other good cylinders. I am more familiar with the Ve pumps but is there something in the p pumps that would allow good pressure to fire the injectors on the other cylinders but not from the 5th cylinder. I replaced the 5th injector with a known good one and it still is not firing or spurting strongly when cracked open. Also there are no broken valve springs and the valves are set correctly. I am strongly suspecting the pump but where do I start to diagnos the problem. do I just pull it and have it rebuilt or are there component s that can be checked with it on the motor. Any help is greatly appreciated, Thanks, Don.
Old 12-08-2008, 10:51 AM
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If you are certain the fuel delivery coming out at #5 is different that rules out a plugged injector. If you're not certain try swapping injectors.

Otherwise it sounds like you have a delivery valve that is sticking or stuck.
You could try swapping the #5 with another one, you will need a delivery valve socket though.
To swap them just follow the first part of the instructions for checking timing here http://dodgeram.info/tsb/1994/18-10-94a.htm
Old 12-08-2008, 11:50 AM
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Thanks for your reply Infidel, further research thanks to your galleries and post have lead me to believe that it is a delivery valve problem.I did swap injectors and the problem stayed with five, so you are saying I could swap delivery valves and check that way too huh? I did notice that the #5 delivery valve was loose on the IP. I know they need to be torqued to 85 ft lbs but with out a socket I carefully tightened the valve with vice grips that meshed with the splines got it retightened to my calibrated hand of 85 ft. lbs. Any way when I went to restart it, it started right up but only ran for about 5 seconds, I assumed it was air so I cracked all the lines to bleed but now it won't even attempt to start. I've gone through a couple charged batteries trying to bleed it to get it to start. Other times all it took was a little bleeding and it would start but since i tightened the DV it won't even sputter.Could tightening the DV have done anything to keep it from starting or do I just keep trying the bleeding procedure. It started and ran great except for the miss on #5 prior to this. Again thanks to anyone willing to help me with advice. Thanks, Don.
Old 12-08-2008, 12:42 PM
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Hopefully you did not put the DV in upside down , same symptoms of start & die , no restart .
Old 12-08-2008, 02:15 PM
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Don't think tfd got as far as swapping DVs to get one in upside down.
I'm not really sure if overtorquing the DV nut would cause problems.
My next move would be to loosen it a little and see what happens.
Can't really go any further until you get a DV socket.
I've heard tale of some P pumps developing a out of round DV barrel from low fuel pressure not providing enough lube and cooling. In this case the DV swap won't improve the problem. In fact it could be hard to pull the #5 DV out.
If the barrel is in fact warped it's injection pump off to the rebuilders.
Old 12-08-2008, 02:27 PM
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I never even removed the dv. All I did was loosen the line nut and the tighten the DV body further then retightened the line nut. I don't think I over torqued the DV because I was aware of the torque requirement and just tightened it till the body was not loose. I will be buying a socket tomorrow and will remove and inspect the DV according to the timing procedure. Is there anything glaring that I should look for? Would messing with the 5th DV like I did above cause me to totally loose the prime to the whole pump? How far exactly do you open the lines to bleed them, I have just been totally loosening them then turning them back till little more than finger tight, also do I tighten them up right away as they start to spit fuel? I've done this successfully several times with different motors but this time it's not even sputtering. thanks again.
Old 12-08-2008, 07:04 PM
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I'm thinking if the barrel is out of round the #5 DV might be hard to remove.
After you have the DV out look for scuffing on the DV and barrel.
True test will come when you swap them and fire it up.

I don't really understand how you lost prime, nothing you did should have caused it.

When you bleed the lines you only need to crack the nut open, half turn is plenty. I crank the engine over till there are no bubbles in the escaping fuel. It will make a mess. Usually just cracking open the first three lines (cylinders 1-3) is enough to purge air enough to get it running. It's not like you have to run to try starting it, once you have clear fuel tighten the line nuts back up then start it.
It will run rough for a few seconds. I usually give quite a bit of throttle to get it started and running right when the system is full of air.

It may sound stupid but make sure you have fuel in the tank and a good charge on the batteries. Try not to crank for more than 30 seconds at a time with a couple minutes inbetween for cooling the starter. Don't want to create another problem.
Old 12-09-2008, 10:50 AM
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I do not always remember all posts to all threads , to save time [ go back & reread ] , Have you checked the fuel pressure from lift pump ?
I swapped out my P pump a few weeks ago , and would use the primer , to manually get most of the fuel going through , with intermittent using the starter .
Old 12-09-2008, 07:51 PM
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I got the truck started today but only after loosening the #5 DV up again, and this time it started only after long periods of cranking and pumping the pedal the injectors (all of them) were also not spurting strongly like they usally do but I still managed to get it started BUT when I went to tighten all the injector lines the truck revved up a little then quickly died again. It then returned to being impossibly hard to start with only weak flow from the cracked injector lines. I call my very helpful diesel shop here (Andy at Desert Diesel, if you are ever in this area) and from what I described to him he was guessing that the plunger on the delivery valve is somehow hanging up on the rack and keep the pump from full fuel mode. He said that he has encountered this on the bench several times and that most of the time it is remedied with a good clean up of the DV with new orings and washers. Does this sound plausible to some of you? I have gotten as far as removing the DV up to cup and little cross thing (?) and have not noted anything glaring obvious. Can I now un bolt the two nuts on the outside of the DV and will that allow removal and inspection of the plunger (lower part of the DV). Is there any trick to getting it out or back in for that matter and what should I look for as far as bad stuff. Thanks a million for any of the help and suggestions offered and sorry for the long replies but I want to be detailed.
Old 12-09-2008, 09:09 PM
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Well I found what was wrong , now how do I fix it. This is what is left of the #5 lower half of the delivery valve (what is the proper name for this). When I unbolted the two bolts this part came off easily at first I thought it was supposed to be like that but on closer inspection I saw that it was cracked all the way around. Is it pump rebuild time? How do I get the rest of the part out, is it supposed to lift out once you unbolt the two nuts? why are the holes slightly slotted does it have to do with timing. I don't want to force the good ones out but I want to see what it is supposed to be like if I can easily remove the other ones.
Attached Thumbnails no firing on 5th cylinder-digital-pics-751.jpg   no firing on 5th cylinder-digital-pics-752.jpg  
Old 12-09-2008, 09:28 PM
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What you removed is the top of the barrel. What you are looking at is the plunger inside. The two holes in the sides are part of the helix in the plunger, which controls how much fuel is injected by when the helix closes the spill ports. I believe the rack has to come out to remove the B&P's, at which point I would send it to a shop. Turning the barrels on the top of the pump affects how much fuel they will move at what rack travel, so to calibrate it properly would need to flow each barrel on a test bench.
Old 12-09-2008, 10:19 PM
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More carnage! the barrel part does come out pretty easily it leaves behind the plunger thing (helix) as you can see on the right #4, the broken helix and barrel came out with a pull from a dental pick. At any rate it looks like pump rebuild time but on the up side my motor only has 71k and I initially thought it was a bent/stuck valve. What can I expect to pay a rebuild shop if I R&R the IP myself? Thanks, Don.
Attached Thumbnails no firing on 5th cylinder-digital-pics-753.jpg   no firing on 5th cylinder-digital-pics-756.jpg  
Old 12-10-2008, 09:11 AM
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The cost of a rebuild is a factor of what the pump shop you choose charges. The local shop here(New England Diesel) will do a P7100 for around $1800 total including removal and installation on the truck. My guess is that you are looking at something like $1500 if you want the whole pump gone through.
Old 12-10-2008, 09:44 AM
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I do not remember where I found these 2 places , but they had the best pricing and talked about modding , a lot of shops only want to do stock work , worrying about warranty .
If anybody knows more about these , I would like to know , I need to replace a P-pump ?

http://www.pensacoladiesel.com/index...ategory_id=193


http://www.usdieselparts.com/category.cfm?Category=165
Old 12-10-2008, 10:58 AM
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What can I expect to pay a rebuild shop if I R&R the IP myself? Thanks, Don.
I consider myself to be a very good mechanic with a well equipped shop but wouldn't even consider rebuilding my own pump.
That's for the guys in the white lab coats.
I usually just trade them in for a Bosch rebuild from here http://www.usdieselparts.com/category.cfm?Category=1009
Good time to upgrade, they offer pumps with plates, GSK and other mods installed and tested.
Just matters how much you want to pay. .
There are many places that offer the same service, I use US Diesel because they are close.


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