Have you considered inspecting your air filter?
It turned out that the Injection Pump was the culprit. After replacing it with a new one, the issue was finally resolved. Grateful for the suggestions provided by others!
I am experiencing a recurring issue with my throttle response. Although it was previously working well, I am now facing a problem with low boost pressure and lack of power. I have thoroughly inspected all connections in the air intake system, from the air filter to the turbo and from the intercooler to the PT Injection pump. Everything appears to be in good condition with no leaks. I have also ensured that my fuel tank is full. Despite these checks, the problem persists. Any suggestions on what could be causing this issue would be greatly appreciated. Thank you.
To start troubleshooting a fuel system issue, consider disconnecting the suction hose from the fuel pump and inserting a short clear tubing section to detect air bubbles while running the engine at high idle. If bubbles are present, move the sight gauge to the fuel filter inlet to check again. If bubbles persist, try installing the tubing at the tank to rule out supply-side problems.
Another step is to test fuel pressure at the injectors using a 1/8 inch pipe plug in the lines leading to the front heads. Contact a pump shop for the correct full load fuel pressure and use a long hose to monitor pressure while driving uphill at full load or accelerating hard.
Additionally, apply about 30psi to the aneroid or fuel pump, if separate on the engine, by connecting a small air regulator to the intake manifold. Drive the truck to check for boost pressure and power improvement. Share your findings for further assistance and suggestions.
Ensure there is a distinct line visible on the return where it is easily observable while driving (look out for bubbles). This issue could be due to compression or air intake problems. Monitor your rail pressure and boost levels as you drive. It is possible that you are experiencing issues with the aneroid. If a small amount of smoke doesn't bother you, you can block it out, but you will need to adjust your fuel usage carefully. I will type slowly as it seems this issue has already been discussed.
I want to express my gratitude for the helpful responses I've received. Dealing with recurring issues after investing in turbochargers and injection pumps can be frustrating. The aneroid receives pressure from the block, downstream of the intercooler. I suspect that the intercooler was not providing enough pressure to signal the pump for more fuel. To address this, I connected a line from my intake manifold directly to the injection pump, bypassing the intercooler. After driving a few miles empty, everything seems to be functioning as it should. I plan to test it with a load tomorrow.
User alaskaforby4 expressed gratitude for the help received regarding issues with turbo and injection pump. They found it frustrating to spend money on repairs only for problems to reoccur. It was discovered that the aneroid was not receiving enough pressure from the intercooler. To address this, a jumper line was connected from the intake manifold to the injection pump to bypass the intercooler restriction. After driving the vehicle empty for a few miles, it appeared to be functioning properly. The user plans to test it loaded the following day. A question was raised about the air pressure going to the aneroid from the outlet side of the intercooler and a suggestion was made to check for a difference in boost pressure between the inlet and outlet sides, indicating a possible restriction in the intercooler.
kshansen inquired about the source of air pressure for the aneroid and suggested checking for a difference in boost pressure between the inlet and outlet sides of the intercooler. A possible restriction in the intercooler could be causing the issue. It is not uncommon to find an aftercooler core clogged with a dust and oil mixture or even a foreign object like a teeshirt in the inlet. It is important to address these issues to prevent damage to the engine.
Grandpa asked if the engine had recently undergone a tune-up. Reader alaskaforby4 shared that despite previous success, the vehicle's performance had dwindled. While throttle response improved, the vehicle lacked power and boost pressure. Despite checking all components from the air filter to the injection pump, the issue persisted. Suggestions included tuning up the engine, adjusting valve lash, and replacing fuel lines for optimal turbo spooling.
Alaskaforby4 expressed gratitude for the helpful replies regarding the frustrating issue with turbochargers and injection pumps. The aneroid receives pressure from the engine block, downstream of the intercooler. It was determined that there may not have been sufficient pressure passing through the intercooler to signal the injection pump for more fuel. To address this, a direct line was connected from the intake manifold to the injection pump, bypassing the intercooler restriction. After driving a few miles without a load, the system appeared to be functioning normally. Further testing will be done with a loaded vehicle. Kshansen inquired about the air pressure to the aneroid and suggested checking for a difference in boost pressure before and after the intercooler, as a restricted intercooler could be the issue. The difference in psi was approximately 5 before and after, dependent on RPM.
User alaskaforby4 noted a 5 psi difference before and after, dependent on RPM. This seems like a significant drop in pressure, especially for engines with intercoolers. Research suggests that pressure loss across the intercooler should ideally be less than 1.0 to 1.5 psi for optimal performance. Any measurement exceeding 4 psi indicates that the intercooler may be ineffective and could negatively impact performance. It would be valuable to know Cummins' perspective on this issue, as a drop in pressure could be attributed to a dirty core or leaks.
The restriction caused by the intercooler was impacting the aneroid valve's functionality. By directly connecting to the aneroid and bypassing the intercooler, the issue was resolved. It appears that the problem lies in a clogged intercooler. This bypassed the intercooler, and connected directly to the aneroid valve resolved the issue. It seems that the root cause of the problem is a blocked intercooler.
It is common for bolts to break off when disassembling the aftercooler, so having a helicoil set on hand before starting is essential. This is especially important for air-to-water aftercoolers.
The issue resurfaced once more. We removed the after cooler and found it to be spotless. The discrepancy in psi readings was due to a difference in gauges. The silicone boot connecting the turbo appeared suspicious, so we replaced it, which provided temporary relief. However, the problem persisted, leaving the vehicle feeling sluggish with no power after just 5 miles of driving. Despite the inconvenience, I managed to navigate short distances at speeds of 10-30 mph. The frustration led me to investigate the fuel supply system and install a gravity-fed auxiliary tank in the cab, but it made no difference. Eventually, I made the decision to purchase another truck but still needed to transport this one to the mechanic located 20 miles away. As I crawled up a hill at 5 mph with a line of traffic behind me, the situation became embarrassingly pronounced, especially with my name prominently displayed on the doors. I pulled over, weighed my options, and with only 10 miles remaining, decided to soldier on for the "slow ride." Surprisingly, the truck performed well for a short distance before reverting to its troublesome behavior. I discovered that turning it off for a minute or two would restore normal power temporarily. After repeating this process a few times, I managed to reach the yard and park the truck, leaving us truly perplexed by the ongoing issue.
The symptoms you've mentioned closely resemble the well-known issue with Cummins fuel lines, as discussed on a popular online forum. This problem involves a rubber flap blocking fuel flow within the hose, causing temporary relief when the engine is stopped but recurring shortly after running again.
alaskaforby4 mentioned that when the vehicle is turned off for a brief period, it starts up with normal power for a short distance. This could indicate a potential fuel-related issue. Without fuel, no turbo can generate boost for the engine.
Have you conducted a thorough inspection of the fuel lines after replacing them? Have you followed the troubleshooting chart for Oregon fuel injection? What is the fuel supply pressure reading? Are you monitoring the pressure on the return line as well?
Since this issue seems to occur consistently and the vehicle runs smoothly under predictable conditions, there should be noticeable variations between the problematic and normal operating states.
It appears that one of your fuel injectors may not be functioning properly.
It is important to note that when one injector fails to fire, it can result in a significant 18% decrease in total power output.
For those with a 350 engine, consider upgrading to a 400 impeller for increased airflow and horsepower. The cost is affordable and the performance benefits are significant.