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93 CTD down on power - help!
Posted By: A727Tflite
93 CTD down on power - help! - 08/29/20 09:46 PM
93 Cummins, 177K miles, auto trans.
Fresh fuel filter 10/2020.
New air filter a month ago.
All original under the hood.
This thing has lost a lot of power - labors pulling 8K lbs.
Best I can tell I am getting 15lbs. boost max. Not sure if that is good or not.
If it is, any ideas on what to look for - the service manual list a host of possible culprits, just wondering if there is something common that goes south on these that could be my issue.
Posted By: NITROUSN
Re: 93 CTD down on power - help! - 08/30/20 12:24 AM
Make sure it has full throttle. If an automatic make sure the tranny is full. These are two simple items I have seen with low power complaints.
Posted By: ro23_j
Re: 93 CTD down on power - help! - 08/30/20 12:45 AM
I have a 91 CTD and I pulled the fuel tank so I could replace all of the rusted brake lines.
I found that the fuel supply line had some pinholes from rust and was seeping fuel. Also, the vent on top of the tank appeared to be blocked with dirt. I replaced the fuel line and cleaned the vent and when I drove it for the first time, it was like a new truck. The last time I towed with it before I replaced the brake lines, it felt like it was down on power.
My assumption is that it was either sucking air through the rusted supply line and/or the vent was not allowing enough air into the tank. Might be worth a look.
Posted By: A727Tflite
Re: 93 CTD down on power - help! - 08/30/20 01:34 AM
I had already checked for full throttle, made sure the fuel shut off valve was not partially engaged.
I had read about the possibility of the fuel tank having issues, going to consider dropping the tank but I think according to the manual, they want you to test fuel line vacuum at the lift pump, or fuel pressure at the lift pump outlet. Need to gather the fittings for that.
Not sure what is faster, dropping the tank or checking vacuum and pressure.
Maybe since this truck is 27 years old it makes sense to drop the tank and clean it out and check for condition.
Thanks for the info.
Posted By: A727Tflite
Re: 93 CTD down on power - help! - 08/30/20 01:35 AM
Make sure it has full throttle. If an automatic make sure the tranny is full. These are two simple items I have seen with low power complaints.
What does trans fluid level have to do with low power? Just wonderin’
Posted By: NITROUSN
Re: 93 CTD down on power - help! - 08/30/20 01:51 AM
Make sure it has full throttle. If an automatic make sure the tranny is full. These are two simple items I have seen with low power complaints.
What does trans fluid level have to do with low power? Just wonderin’
Ran into a complaint years back. The guy had a rubber transmission line blow off. He never told us the whole story at first. He added some fluid but he did not get it full. The truck was a dog and his complaint was low power. We added several quarts and it was back to normal. I can only attribute the condition to the large converter fluid capacity. Lower fluid did not allow the transmission/converter to make power. It did not act like a low fluid problem. Just a suggestion.
Posted By: J_BODY
Re: 93 CTD down on power - help! - 08/30/20 01:56 AM
I might be old.... but I’m not VE pump old! I thought your explanation of “lack of power” described a stock one to a T!
Any witness marks around the pump mounting bolts? Years of vibration may have allowed the pump to move.... I know, I’m grasping here...
Posted By: RTSrunner
Re: 93 CTD down on power - help! - 08/30/20 03:19 AM
Maybe a collapsed exhaust pipe (some are double walled) or a clogged muffler.
Posted By: ruderunner
Re: 93 CTD down on power - help! - 08/30/20 09:30 AM
I've heard that the rubber tip of the KSB can come loose and partially block the incoming fuel.
Posted By: A727Tflite
Re: 93 CTD down on power - help! - 08/30/20 04:12 PM
Thanks for all the tips.
It has a newer Bullly Dog exhaust system on it, may be two years old, three years max.
I have a diesel expert going to look at it, I’m backlogged with work on other projects.
Posted By: NITROUSN
Re: 93 CTD down on power - help! - 08/30/20 08:09 PM
This is a copy and paste from Geno's Garage.
A check of the low-power-complaint basics.
Following is a list of easy-to-do items the owner can perform
:- check for quality of fuel-
check for full travel of the throttle lever at the fuel pump-
check all turbo-to-intercooler and intercooler-to-intake manifold hoses and clamps for a tight fit-
check the condition of your fuel filter-
check for fuel inlet restriction-
check the condition of your air filter-
check for exhaust leaks prior to the turbocharger-
check for exhaust system restriction
for automatic trucks; check your transmission fluid level
Posted By: A727Tflite
Re: 93 CTD down on power - help! - 08/30/20 11:26 PM
This is a copy and paste from Geno's Garage.
A check of the low-power-complaint basics.
Following is a list of easy-to-do items the owner can perform
:- check for quality of fuel- good
check for full travel of the throttle lever at the fuel pump- done
check all turbo-to-intercooler and intercooler-to-intake manifold hoses and clamps for a tight fit- done
check the condition of your fuel filter- new
check for fuel inlet restriction- pending
check the condition of your air filter- new
check for exhaust leaks prior to the turbocharger- none
check for exhaust system restriction - how? At idle it feels like normal exhaust pulses
for automatic trucks; check your transmission fluid level. done.
Posted By: NITROUSN
Re: 93 CTD down on power - help! - 08/31/20 12:40 AM
I am not sure on the boost level on the 1st gen trucks. 15 may be close. I doubt it is over 20. Generally if you do not have enough fuel you can not make boost. I have heard of weak lift pumps causing a lack of power. Not sure what the fuel pressure should be for that style lift pump but as long as it has positive pressure to supply the injection pump it should be enough to give the pump all it needs. Dirty of partially plugged injectors could also play in.
Posted By: NITROUSN
Re: 93 CTD down on power - help! - 08/31/20 01:20 AM
Another thought if you hold it in first gear what rpm does it reach before the governor kicks in? Will it do the same in each gear? I know when the throttle position sensor act up you loose a top gear same with the speed sensor which I believe you would be on to those symptoms.
Posted By: Guitar Jones
Re: 93 CTD down on power - help! - 08/31/20 01:56 AM
I am not sure on the boost level on the 1st gen trucks. 15 may be close. I doubt it is over 20. Generally if you do not have enough fuel you can not make boost. I have heard of weak lift pumps causing a lack of power. Not sure what the fuel pressure should be for that style lift pump but as long as it has positive pressure to supply the injection pump it should be enough to give the pump all it needs. Dirty of partially plugged injectors could also play in.
Mine can hit 36 on a good day. Lack of fuel is the usual culprit. Fuel lines sucking air, weak lift pump and clogged fuel filter are the most likely. When was the last time you changed the fuel filter? Apparently it's still in the future, unless you live in a time warp or something.
Posted By: W.I.N. Racing
Re: 93 CTD down on power - help! - 08/31/20 04:12 PM
Is it blowing Any more smoke than normal?? look at the intercooler hoses/tubes. Make sure they are fully connected and not leaking. Also look at the intercooler for leaks.
Posted By: A727Tflite
Re: 93 CTD down on power - help! - 08/31/20 09:00 PM
Still waiting for the expert to call me.
New filter, I can’t get more than 15 boost, all the external air lines and rubber flex connections are good and tight, only some dark smoke on startup.
It was never a rocket ship, more like a peppy brick but I pulled twice the load out of Portland in 2013 than I just did and it felt pretty strong then compared to now.
Posted By: Guitar Jones
Re: 93 CTD down on power - help! - 08/31/20 11:51 PM
Still waiting for the expert to call me.
New filter, I can’t get more than 15 boost, all the external air lines and rubber flex connections are good and tight, only some dark smoke on startup.
It was never a rocket ship, more like a peppy brick but I pulled twice the load out of Portland in 2013 than I just did and it felt pretty strong then compared to now.
Adjust the valves. Check the fuel pressure before and after the filter. Pull the fuel shut off solenoid and inspect it. They have been known for the rubber to come apart and clog the fuel feed to the VE pump. Past that pull the injectors and have them cleaned and pop tested. Remove the intake hose and check the turbo, make sure the blades aren't damaged and it spins freely. Make sure the shaft is tight and the blades aren't scraping the housing.
Posted By: hemi70se
Re: 93 CTD down on power - help! - 09/02/20 04:36 AM
This may not be your problem but just throwing it out there. Back in 1998 I had a late build 1990 CTD with an Intercooler. It had lower power than it should have had. Turned out to be the aluminum intercooler had a hole in it from corrosion.
Posted By: Twostick
Re: 93 CTD down on power - help! - 09/07/20 03:29 AM
As has been said, check the intercooler. Pull the hoses and plug one end and make up a fitting to clamp in the other end with a valve and a pressure gauge. Air it up to about 30 psi and close the valve. If it loses more than 5 psi in 15 seconds, it's FUBAR. For your problem it would have to have a substantial leak so it should pretty much go to zero as soon as you close the valve.
How much fuel pressure? No fuel, no boost, no power.
According to this article, 25 psi is minimum.
Some good info for both P pump and VE.
https://www.dieseltuff.com/instructions/Kevin
Posted By: J_BODY
Re: 93 CTD down on power - help! - 09/13/20 09:36 PM
WELL???
Posted By: Guitar Jones
Re: 93 CTD down on power - help! - 09/14/20 11:24 PM
Probably still waiting on the "expert".
Posted By: J_BODY
Re: 93 CTD down on power - help! - 09/15/20 02:14 AM
Or driving it home.... they’re pretty slow
Posted By: Guitar Jones
Re: 93 CTD down on power - help! - 09/15/20 09:26 AM
Posted By: NITROUSN
Re: 93 CTD down on power - help! - 09/17/20 01:54 PM
What is the verdict?
Posted By: J_BODY
Re: 93 CTD down on power - help! - 09/18/20 12:13 AM
P pump and compounds is what I’m speculating
Posted By: Guitar Jones
Re: 93 CTD down on power - help! - 09/18/20 10:50 AM
Posted By: NITROUSN
Re: 93 CTD down on power - help! - 09/27/20 02:03 AM
Well did you get it fixed???
