TheBigNasty

When I bought this truck it already had PDR 191 DV's....for the past 2 yrs I have had it no problems. Well recently me and the previous owner noticed a leak at the DV holder. I used his socket, replaced the o-ring, tightened it down, bled the lines at the injectors, and now it has a bad idle which clears up after 900-1000rpm. No noticeable loss of power, just a bad idle. It is not as bad as a miss, there was a noticeable drop when i cracked the lines at the injectors while it was running as per AllData recommendation. Maybe I didn't bleed it enough? I'm pretty positive all the air was out of the lines. One thing I did notice though is that in PDR's instructions it says to remove the copper gaskets that come factory if it has them. Mine still has them. Is there a different design or were they just never removed like they were supposed to be? Even if they are not supposed to be there, why did it work and does not anymore?

12valve

hmmm not sure, i had a truck that idled bad cuz the lift pump was going bad.

test that with a fuel pressure gauge.

but it could be sumthin dif though!

TxDiesel007

I kinda of agree with Silvano on this one..

If they were fine before, and ur DV holder went bad and started leaking, it could possibly be picking up air, or ur LP could be bad... I have a slight leak at my first injector line and ive swapped out to 191s and 181s before, and ive had no bad idle..

Perhaps u should check the OFV as well, or the rubber lines behind the truck, Remember front fuel line, rear return line in the rubber lines, If you have a Fp gauge check to see what ur pressure is and if the pressure shoots up when u pinch the line, chances are ur OFV is bad, if pressure remains constant, then ur LP mighta taken a dump... they aint fun to change either, but they aint too bad...

Rick

TheBigNasty

It is just odd that it would do it in the process of tightening the DV holder...i mean I shut it down, tightened the holder up, bled the lines, and then bad idle. There are no apparent leaks so ????? I am in the process of hooking up my FP gauge tho so I will know for sure.

smoke_pedal

is one cylinder hitting really hard, or sofe, and the other ones normal? can you follow it and predict when it is going to happen, because if so, you torqued it to the point where you moved your barrel in your pump. you could have possibly caused the dv to stick by overtightening it too.

TheBigNasty

Pretty much about the symptom.....but i tightened it to 85 ft lbs like PDR's instructions said. If I did overtighten it, due to BigBlue's "awesome" torque wrench, should i just take it back or did i cause permanent damage?

smoke_pedal

look at the barrels on the pump. look at where the nuts are, and see if the one you torqued slid any. see if it is at the same angle as the others. when pumps are calibrated on a flow bench, this is the main thing that is adjusted. They are adjusted for balanced flow from all of the cylinders. if you are convinced that it did rotate some, then my best advice would be to

1: loosen the two nuts a very little bit, loosen the nut to the injector just enough that you can turn the whole assembly, and when you get a good feel for what it takes to turn the thing, make sure your nuts (on the pump and on your bumper) are snug, and start the engine. your pump rack gear engages with a gear on the side of the barrel, so if the whole barrel assembly is allowed to lift any, it will bend the rack. that would be very bad. you turn the whole barrel assembly until you hear that cylinder hit hard, then back it off until you hear that cylinder die off a little, and then you go back to the middle. remember it is better to have a little less fuel to that cylinder than too much. I will give up 10 hp to not melting a piston. when you tighten the hold down nuts, it will tend to give you a little more fuel than the last place you adjusted it, due to more plunger travel, so take that into account. tighten your injection line nut. At idle, your injection system doesn't put out nearly as much pressure as when it is at full fuel, so you should be able to find a sweet spot where the injection line doesn't leak, but you can still turn it. Just make sure this is your problem before you go messing with the barrel adjustment. it will be evident that your barrel turned by scraped paint under the nuts, and the ears will be a lot closer to the next one aft on the top than the other ones.

Another thing to take into account is that the delivery valve needs to be torqued with one smooth motion, rather than going to 60, then 85 lbs. the copper seal will not crush evenly if you didn't do it in one smooth motion. you should be all right backing it off and doing it again without using a new seal if you think that might be the problem. it might be a little piece of dirt in the delivery valve from when you put it together, not letting it seat properly. if that is the case, it may smooth out when you get to a higher injection pressure.

TheBigNasty

No cracked paint so I don't believe I moved the barrel. I did tighten it in one smooth motion, set the torque wrench and pulled till it clicked. Now I did not replace the washer, just checked it to make sure it looked fine. I don't even know if it should be in there because PDR's instructions say to discard them, but it has worked so far with them in there. Maybe there is dirt in there, I didn't remember seeing any but wouldn't hurt to check. I would have cleaned everything with B12 like i always do but didn't have any available at the time.

12valve

How did your problem work out?

i had a guys pump who had a little piece of dirt right at the dv, IIRC,
i replaced the barrel back then and it worked, I saw the dirt lateron after i opened it!

Then there was another guys pump who did the same thing, his lift pump was bad.

Another good friend had a cracked injector...

Hope everything works out nicely for you!

Cowhand

Did you try calling Harry or Piers? They've always been great about helping me diagnose annoying little problems like this......

TheBigNasty

Well, finally got around to calling Piers. Said the washers are NOT supposed to be in there but it will run w/o them, so they are coming out. I am also working on my OFV right now, trying to figure out how to get this thing out. It keeps hitting the manifold so I'm looking to see if there are any tricks short of getting a dremel and grinding a little out of it. I'll let you all know how it turns out.

TheBigNasty

Well, the fuel press was raised, 45 at idle and will not go below 20. Finally got off my butt and got the washers out. They were mashed and mangled in there but now, wow, it idles and drives so much smoother.