Injection pump problems? - Dodge Cummins Diesel Forum
94-98 Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission Ect...NO ADVERTISING

 1Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 35 (permalink) Old 07-15-2019, 11:56 PM Thread Starter
Cummins Fan
 
Join Date: Jul 2012
Location: Montana
Posts: 64
Thanks: 4
Thanked 2 Times in 2 Posts
iTrader Score: 0 reviews
Injection pump problems?

I have a 94 with 265k on the clock. I installed a pdd power pack with 025 delivery valves, 5x11 injectors and the AFC live. Truck ran like an animal. Smoked really bad at full fuel, but ran hard. I noticed ever since the install, after the truck warmed up, it had a choppy unhealthy idle. Cruising through the gears under small throttle you could hear a fluttery sound from the exhaust. If my bed was loaded with weight or I had a trailer on, the whole truck would shake at an idle. Recently I grew tired of it, so I tried my stock delivery valves. Idle completely smoothed out and it runs clean and smooth like it did before the install. I called pdd to explain the issue and they said it was because my injection pump is going out and it can't handle the extra flow from the valves. I find that answer strange seeing how it runs fine at wot where I would think a bad ip would show it's self. I'm happy with how it runs with the stock valves, but I don't want it to strand me.


94 RC/LB 2500 nv4500
danzick is offline  
Sponsored Links
Advertisement
 
post #2 of 35 (permalink) Old 07-16-2019, 07:20 AM
Moderator
 
9297oldram's Avatar
 
Join Date: Sep 2010
Location: Huntington In.
Posts: 20,059
Thanks: 631
Thanked 2,178 Times in 2,035 Posts
iTrader Score: 0 reviews
Do you have a fuel pressure gauge on it to see what your fuel pressure does when your having a problem when it's running?

84 K5 Blazer 97 12v, 47re with E-TransControl, Dodge Dana 60 with free spin hubs, Dana 70, B&M Mega shifter

96 F350 SC dually zf5, 4x4, 92 Cummins, THD 5x12's, THD fuel pin, THD HVLP with adjustable fuel pressure mod, WM, h1c 60/60/12cm WG wired
9297oldram is offline  
post #3 of 35 (permalink) Old 07-16-2019, 08:56 AM
Diesel Head
 
GAmes's Avatar
 
Join Date: Sep 2009
Location: Killeen, TX
Posts: 16,082
Thanks: 149
Thanked 1,733 Times in 1,518 Posts
iTrader Score: 7 reviews
PDD is afraid you will want to return the DVs. There isn't anything wrong with the pump. If you were to put the truck on a dyno there wouldn't be a significant change in HP/TQ with or without the oversize DVs. The upside is your mileage will improve now that they are removed.

97 3500, 2 WD, G56, slightly bombed, 1.3 million miles. Started the second million on 8/24/13
If you are lucky enough to be in Texas, you are lucky enough.
To view links or images in signatures your post count must be 3 or greater. You currently have 0 posts.
GAmes is offline  
Sponsored Links
Advertisement
 
post #4 of 35 (permalink) Old 07-16-2019, 09:09 AM Thread Starter
Cummins Fan
 
Join Date: Jul 2012
Location: Montana
Posts: 64
Thanks: 4
Thanked 2 Times in 2 Posts
iTrader Score: 0 reviews
Quote:
Originally Posted by 9297oldram View Post
Do you have a fuel pressure gauge on it to see what your fuel pressure does when your having a problem when it's running?
Yes, that's another funny thing. I told him I have the fuel pressure set at 22 psi idle and he said it should be in the high 20s around 28. That seems crazy high to me. He also said I should be at 80 psi wide open. Is that realistic? I'm actually at around 10 psi under a hard wot pull which does seem low but that's with a snubber.

94 RC/LB 2500 nv4500
danzick is offline  
post #5 of 35 (permalink) Old 07-16-2019, 09:12 AM Thread Starter
Cummins Fan
 
Join Date: Jul 2012
Location: Montana
Posts: 64
Thanks: 4
Thanked 2 Times in 2 Posts
iTrader Score: 0 reviews
Quote:
Originally Posted by GAmes View Post
PDD is afraid you will want to return the DVs. There isn't anything wrong with the pump. If you were to put the truck on a dyno there wouldn't be a significant change in HP/TQ with or without the oversize DVs. The upside is your mileage will improve now that they are removed.
That's kind of what I gathered. I tried the "cold water trick" when it was acting up and nothing changed. It doesn't have any other symptoms either like a low idle or dying and not starting again.

94 RC/LB 2500 nv4500
danzick is offline  
post #6 of 35 (permalink) Old 07-16-2019, 09:48 AM
Diesel Head
 
GAmes's Avatar
 
Join Date: Sep 2009
Location: Killeen, TX
Posts: 16,082
Thanks: 149
Thanked 1,733 Times in 1,518 Posts
iTrader Score: 7 reviews
The engine will run, drive and idle smoothly with zero pressure once it is running. Been there, done that. I drove through downtown traffic in Salem, OR with a travel trailer in tow looking for a parking lot big enough to pull into. The fuel pressure was at zero because the bolt that holds the filter canister to the housing had broken. The canister dropped about an inch and fuel was gushing out for over a mile when I pulled into an auto parts store parking lot. The pressure specs are outlined in the FSM. You have plenty. The PDD adviser needs some education.

97 3500, 2 WD, G56, slightly bombed, 1.3 million miles. Started the second million on 8/24/13
If you are lucky enough to be in Texas, you are lucky enough.
To view links or images in signatures your post count must be 3 or greater. You currently have 0 posts.
GAmes is offline  
post #7 of 35 (permalink) Old 07-16-2019, 10:42 AM Thread Starter
Cummins Fan
 
Join Date: Jul 2012
Location: Montana
Posts: 64
Thanks: 4
Thanked 2 Times in 2 Posts
iTrader Score: 0 reviews
Thanks for the info. Glad to hear my pump is probably ok. I will add that the truck did seem to loose power when I went back to stock. I cannot understand why it black smoked so bad with them? It's not like they were full cuts. It was a steady thick "roll coal". Now, it's a haze of black at full throttle and Max fuel switch on.

94 RC/LB 2500 nv4500
danzick is offline  
post #8 of 35 (permalink) Old 07-16-2019, 10:57 AM
The Uppity 12v Guy
 
dauntless89's Avatar
 
Join Date: Jul 2013
Location: Cedar City, UT
Posts: 7,704
Thanks: 848
Thanked 1,319 Times in 948 Posts
Garage
iTrader Score: 1 reviews
Balance issues on a P-pump are much more likely to present at idle than at WOT. Aggressive DVs will exacerbate a normally imperceptible balance issue, as more aggressive DVs contribute less to fuel metering. If the pump doesn't run well with more aggressive DVs, the DVs either need to be put back to stock or a more mild cut, or the pump needs to be balanced with the new DVs. That said, a rebalance is often a bandaid as the underlying cause is one or more plungers being weak in the idle rack position. It's also certainly possible that set of DVs you ended up with is defective in some way. I would call PDD and exchange them for a different set of the same ones.

P7100 fuel pressure recommendations in performance circles are both consistent with what you were told and differ from published specs for stock applications. There's nothing in a P7100 that can be damaged by high fuel pressure. There are significant gains to be had in hydraulic efficiency of the injection elements going from 20s to 40s on all pumps, and 160/175hp pumps see even further gains at high RPM going from 40s to 60s and beyond. Basically all drag and pulling truck applications run at least 60-80 psi under load. 100 psi is not uncommon and I've heard of people running 120, though that seems to be about the end of the "diminishing returns" zone. Your FASS and Airdog pumps are set around 45 psi which gets you 80-90% of the gains to be had in a street truck.

22 psi (while on the low side in a performance application) is not causing a lope or chop at idle. 10 psi under load is not going to mechanically hurt the pump, but it is absolutely costing you power. I see you have a 175hp pump, you could pick up as much as probably 30 rwhp if you get it up into the 60s. I'd expect at least 20rwhp if you can get it into the 40s.

'95 2500 ECLB 4x4, 334k and paused due to epic transformation in progress.
dauntless89 is offline  
post #9 of 35 (permalink) Old 07-16-2019, 11:14 AM
Diesel Freak
 
Join Date: Oct 2007
Location: Phoenix, AZ
Posts: 640
Thanks: 22
Thanked 48 Times in 47 Posts
iTrader Score: 0 reviews
I had a 180 pump that was balanced with 022 DVs that had a bit of a funky idle. Only when in N or P. D would smooth it out. I wanted to try a set of 181s in it to experiment but ended up with a 215 pump instead. Since then ive come to the conclusion that DVs can absolutely affect idle quality.

However these minor performance upgrade DVs shouldn't affect idle on an otherwise healthy pump. At 275k it is possible the pump is just enough out of balance to show itself with a larger DV. I think as well these 160HP pumps are more finicky than the rest. (E.g. higher tolerances in P&B) Did the idle clean up any if you raised engine RPM slightly? You may be abke to get away with adjusting the low idle stop.

Sent from my LG-H932 using Tapatalk

91.0 D250 A727 w/ 216k on the clock. i/p replaced 20k ago, lift pump 2k, 1 turn fuel, 2 turns smoke, ground & polished AFC pin, timing bump, 366 spring 94 2500 4x4, 49k miles, Farrell Diesel rebuilt 215 pump, PDD 5x12 SAC, SXE 362, built 47RH
hemirunner426 is offline  
post #10 of 35 (permalink) Old 07-16-2019, 11:24 AM Thread Starter
Cummins Fan
 
Join Date: Jul 2012
Location: Montana
Posts: 64
Thanks: 4
Thanked 2 Times in 2 Posts
iTrader Score: 0 reviews
Quote:
Originally Posted by dauntless89 View Post
Balance issues on a P-pump are much more likely to present at idle than at WOT. Aggressive DVs will exacerbate a normally imperceptible balance issue, as more aggressive DVs contribute less to fuel metering. If the pump doesn't run well with more aggressive DVs, the DVs either need to be put back to stock or a more mild cut, or the pump needs to be balanced with the new DVs. That said, a rebalance is often a bandaid as the underlying cause is one or more plungers being weak in the idle rack position. It's also certainly possible that set of DVs you ended up with is defective in some way. I would call PDD and exchange them for a different set of the same ones.

P7100 fuel pressure recommendations in performance circles are both consistent with what you were told and differ from published specs for stock applications. There's nothing in a P7100 that can be damaged by high fuel pressure. There are significant gains to be had in hydraulic efficiency of the injection elements going from 20s to 40s on all pumps, and 160/175hp pumps see even further gains at high RPM going from 40s to 60s and beyond. Basically all drag and pulling truck applications run at least 60-80 psi under load. 100 psi is not uncommon and I've heard of people running 120, though that seems to be about the end of the "diminishing returns" zone. Your FASS and Airdog pumps are set around 45 psi which gets you 80-90% of the gains to be had in a street truck.

22 psi (while on the low side in a performance application) is not causing a lope or chop at idle. 10 psi under load is not going to mechanically hurt the pump, but it is absolutely costing you power. I see you have a 175hp pump, you could pick up as much as probably 30 rwhp if you get it up into the 60s. I'd expect at least 20rwhp if you can get it into the 40s.
I was hoping he would offer since I told him how unhappy I was with them, but he only seemed interested in having my pump gone through for 1200 not including parts.

94 RC/LB 2500 nv4500
danzick is offline  
post #11 of 35 (permalink) Old 07-16-2019, 11:30 AM Thread Starter
Cummins Fan
 
Join Date: Jul 2012
Location: Montana
Posts: 64
Thanks: 4
Thanked 2 Times in 2 Posts
iTrader Score: 0 reviews
Quote:
Originally Posted by hemirunner426 View Post
I had a 180 pump that was balanced with 022 DVs that had a bit of a funky idle. Only when in N or P. D would smooth it out. I wanted to try a set of 181s in it to experiment but ended up with a 215 pump instead. Since then ive come to the conclusion that DVs can absolutely affect idle quality.

However these minor performance upgrade DVs shouldn't affect idle on an otherwise healthy pump. At 275k it is possible the pump is just enough out of balance to show itself with a larger DV. I think as well these 160HP pumps are more finicky than the rest. (E.g. higher tolerances in P&B) Did the idle clean up any if you raised engine RPM slightly? You may be abke to get away with adjusting the low idle stop.

Sent from my LG-H932 using Tapatalk
Not really. The choppy sound in the exhaust just got a little faster. The truck wouldn't shake as bad though. I had to adjust my preboost screw a ton. I probably had to turn it out 2 or 3 turns. At that point I didn't think I was even touching the diaphragm, so I had to slide the housing back.

94 RC/LB 2500 nv4500
danzick is offline  
post #12 of 35 (permalink) Old 07-16-2019, 11:51 AM
Diesel Freak
 
Join Date: Oct 2007
Location: Phoenix, AZ
Posts: 640
Thanks: 22
Thanked 48 Times in 47 Posts
iTrader Score: 0 reviews
Quote:
Originally Posted by danzick View Post
Not really. The choppy sound in the exhaust just got a little faster. The truck wouldn't shake as bad though. I had to adjust my preboost screw a ton. I probably had to turn it out 2 or 3 turns. At that point I didn't think I was even touching the diaphragm, so I had to slide the housing back.
You can raise the idle and deal with the chop. It isn't hurting anything really. dauntless89 is pretty on point with his synopsis of what is going on. Tighter tolerances with P&B on the 160/175 pumps were noted for higher premature failure, likely due to heat soak/heat cycles, and poor filter media/maintenance. The only way to find the condition of the pump is to pull the pump off and bench it.

It could also be that there is a defect in the DVs you received from PDD. Maybe you could ask to try a replacement set to rule that out?

91.0 D250 A727 w/ 216k on the clock. i/p replaced 20k ago, lift pump 2k, 1 turn fuel, 2 turns smoke, ground & polished AFC pin, timing bump, 366 spring 94 2500 4x4, 49k miles, Farrell Diesel rebuilt 215 pump, PDD 5x12 SAC, SXE 362, built 47RH
hemirunner426 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Dodge Cummins Diesel Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome