red truck, it seems like we've got the same truck! I know we had the same EGR problems earlier this year and now I see you're having the same problems that I was a couple of weeks ago. However, I'm also having overheating issues to go with it. Here's what I've done and found so far. My intake and throttle body were beyond dirty. I removed both of those and cleaned thoroughly with carb and choke cleaner and a toothbrush. While I was at it, I replaced all of the injectors and my problem got slightly better. Then, I decided to drop the tank and replace the fuel pump, pressure regulator and fuel filter. After that, the problem got significantly better. Now, I only notice the pinging if I'm hauling something really heavy and I'm in 4th or 5th gear going up a steep grade.

 

you shouldnt have to if you use an oil flush because it breaks down all the sludge and throws it into the filter to clean it all up.

 

Big time. Get yourself a set of fitted wires. Super Stock's are junk, just go with the default wires from your local auto parts store. Use the separators that come with the wires to keep them from touching each other. This is especially important on the drivers side.

 

I made time to do a fuel pressure check this morning.
Engine off pressure about 40 ok
Engine running about 31 ok but on the lower end

I did the static pressure leakage check and the pressure dropped immediately. My Haynes manual said that it should stay within 5lbs for at least a minute. From the time that I turned it off and checked under the hood there was no pressure.

The Haynes directions said to crimp the return line off. I did this and the pressure dropped at a slower rate, but definitely dropped quicker than it should have. I crimped off the supply line and saw no change. I am concerned about damaging the lines with the crimping, so I did not try very hard.

I removed the regulator and connected a piece of vacuum hose to the fuel connectors and could not blow air through either side. Does that mean anything? I may go ahead and replace the regulator, but am not sure if it is the problem.

The Haynes manual said 3 things could be at fault, regulator, fuel pump or leaking injectors. Based on what I see, it appears that the regulator to indicates some problem, since crimping the hose made a difference. I think I got the right hose. The blue one that connects to the fuel rail should be the supply from the pump, and the black one that is connected to the bottom of the regulator and goes to the frame should be the return. Correct?

On another note. I checked my plug wires and rerouted them. While I was doing this I noticed that the distributor cap was rocking back and forth on the distributor. I got a new one and noticed that the old one had a misshaped base and did not sit flat. I have never run across that before.
Thanks for your help. I will try more tomorrow and could use a second opinion on what I have found.

By the way, any opinions on cheap regulators from discount auto parts? I have found on $18 and the next is $40.

 

What was the fuel pressure running with the vacuum hose to the regulator disconnected and plugged?

Was there any signs of gas in the vacuum hose to the regulator?

Did the plug wires and distributor cap make any difference?

 

I do not remember the exact pressure with the engine running and the vacuum line plugged. I believe it was around 50-60lbs. I do remember that it increased. I could recheck if that would give a clearer picture as to what is going on.

I saw no sign of gas in the vacuum line. I put a piece of hose on that end and checked and it held vacuum.

As for the cap and wires, I drove it a short distance and could not hear a knock on hills, but that has happened before. There still seemed to be a slight flutter in the engine at idle, but it ran well. I have not taken the truck on the highway with a load since, but will in a couple of days.

I also used sea foam on the intake and in the tank. I picked up a new regulator tonight and will try it asap.
Thanks,

 

It sounds to me like your regulator is fine, but if you already picked up another one, go ahead and try it, but you really should go for a good test drive first. Otherwise if the problem ends up being fixed, you won't know if it was the ignition parts that fixed it or the regulator.

 

I tried the new regulator. No changes with the fuel pressure. It holds 40 lbs without the vacuum connected. The other numbers were the same as I remembered. I positioned the pressure gauge until I could see it through the gap in the raised hood and the pressure dropped to 0 in about 5 seconds.

I assume that there is some type of check valve in the fuel pump that may not be working properly. Is there any simple way to confirm that this is the problem or to connect it to a fuel injector? I am really uncomfortable with the Haynes procedure of crimping off the fuel line. These appear to be reinforced plastic with a rubber coating. It did not return to shape like a rubber line and I was afraid of weakening it and causing a leak.

Is there something else that I should look at besides the pump and injectors? I would like to just start replacing parts, but $ is limited, and those can both be rather expensive.

I am suspicious of the injectors. While I was working on my EGR problems, I got some codes related to fuel mix. I changed the O2 sensor and it showed up again later. I have never worked on injectors, but have my manual.

I was thinking the same thing on the test drive issue. To get a good test run, I need to pull my trailer at highway speed up a steep grade. I have to go about 15 minutes away to do that. I will try to this week. Thanks for all the help.

 

Just out of curiosity, how many gas tanks do you have? If you have two, did you test to see if the leakdown was the same for both tanks? If so, your injectors are leaking. Your best bet would be to get a set of rebuilt ones, they aren't difficult to install.

 

Only have one tank. I'll do some more next week. Do I necessarily need to replace all the injectors, or can I isolate the ones causing trouble?

 

You don't have the equipment necessary to identify which injectors are good and which are bad. Besides, you really should replace them as a set anyway. It doesn't have to be expensive. Good Deal

 

I agree. Believe it or not I have been watching those on ebay. I started a thread about choosing them b/c this one seemed to be running thin. I am going to try to do a road test tomorrow with my trailer. I think I may go ahead and change the temp sensor and see if that makes a difference. I have read a lot on here about those showing up as problems. I plan to order the injectors in the next couple of days.

Thanks for all your help.

 

I was under the impression you had already installed a new ECT sensor. A new one may do wonders for you, but the only thing that is going to fix your leaky injectors is replacing them. In other words, even if the ETC makes life wonderful again, you still have another problem to deal with.

 

I had not ran into anything with the ECT Sensor to this point. No codes relating or anything. I read about it while searching through some old threads.

I agree 100% on the injectors. It is my understanding that the ECT can make night/day difference in how the truck runs. I would like to try it before I get into the injectors b/c I plan to go through the plenum and throttle body while I have them off. If the ECT is the primary issue, it may buy me some time.

By the way, I noticed what appeared to be oil residue under the throttle body on what I believe to be the position sensor. Does that mean anything?

 

Not necessarily. Have you tested your TPS?