Mechanicalull08
04-04-2013, 14:18
Hello everyone, this is my first post so here goes.
I have a 1993 C2500 6.5L TD 2wd, 4L80E. I am the second owner and have known and helped maintain the truck since 1997. It currently has 448,000 miles on the truck and engine, the transmission was rebuilt at 295,000. I was very close to the original owner and so I have a special attachment to the truck and plan on keeping it going for a long time.
So here is the issue, when I became the owner in '09 with 405,000 miles it would start and run like it had air in the fuel once every 2 or 3 weeks, so very hard to pinpoint what was going on. If I stopped and let it sit for at least 15 minutes it would start right away and you would here a sharp 2 or 3 knocks and it would clear up. If I kept driving it while it was running like this, I was able to clear the issue by putting the truck in neutral and revving up the engine and it would make that same sharp noise, puff out a good cloud of greyish black smoke and run fine again.
Over the years and miles it has progressively occurred more frequently, usually on a cold start, and on the occasion when it starts smooth. As I am first driving done the road and let off the accelerator it will start missing like I have air in the lines. While running rough the exhaust will have a greyish tint to it, but not like that is all that is coming out and if running smooth, then exhaust is clean. Once it warms up I have always been able to clear the issue through the earlier method and have driven many long distances and it will not occur again within that drive cycle. Every so often it will happen on a hot restart but very infrequent.
What I have done to remedy the issue to no avail:
Dropped the tank and cleaned sock (couldn't get a replacement at the time) fixed other issues and got mpg back, but not this issue-Done 410,000 miles
Replaced injectors with new Bosch and new return lines- Done 440,000 no change with issue, but when I installed them I did the non-turbo side first and ran engine to clear air out and the same noise occurred as described earlier when the new injectors were clearing the air out. Which is why I think it is air in the lines.
Dropped and replaced the sending unit in the tank-Done 442,000 no change with issue
Replaced fuel lift pump, I have an external fuel pressure gauge mounted under the hood to monitor fuel return pressure and was 4 psi before replacement and now 5-7 psi. Done 442,000 no change in issue
Replaced all of the remainder rubber lines on the fuel system under the hood, the two return hoses at the front, the one at the firewall, all the ones connected to the filter housing. the one from the filter housing to the injection pump became wet as i first grabbed it and was very dry rotted, i thank God thinking i had finally found the source of my frustration-Done 447,000 no change in issue.
I have changed the fuel filter many times also and the only mods the truck has is a turbo master from heath and a full mandrel 3" exhaust, I have the boost set @ 10 psi. I do have a boost gauge and EGT gauge.
I plan on keeping the truck for a long time, at least till 1,000,000 mile mark, and at some point what to take it off the road and restore it to its original glory. But right now it is my daily driver. I am leaning to a new IP pump and new Timing set, but don't want to replace all of that and it not be the issue. Any help would be greatly appreciate.
Thanks Blaise
I have a 1993 C2500 6.5L TD 2wd, 4L80E. I am the second owner and have known and helped maintain the truck since 1997. It currently has 448,000 miles on the truck and engine, the transmission was rebuilt at 295,000. I was very close to the original owner and so I have a special attachment to the truck and plan on keeping it going for a long time.
So here is the issue, when I became the owner in '09 with 405,000 miles it would start and run like it had air in the fuel once every 2 or 3 weeks, so very hard to pinpoint what was going on. If I stopped and let it sit for at least 15 minutes it would start right away and you would here a sharp 2 or 3 knocks and it would clear up. If I kept driving it while it was running like this, I was able to clear the issue by putting the truck in neutral and revving up the engine and it would make that same sharp noise, puff out a good cloud of greyish black smoke and run fine again.
Over the years and miles it has progressively occurred more frequently, usually on a cold start, and on the occasion when it starts smooth. As I am first driving done the road and let off the accelerator it will start missing like I have air in the lines. While running rough the exhaust will have a greyish tint to it, but not like that is all that is coming out and if running smooth, then exhaust is clean. Once it warms up I have always been able to clear the issue through the earlier method and have driven many long distances and it will not occur again within that drive cycle. Every so often it will happen on a hot restart but very infrequent.
What I have done to remedy the issue to no avail:
Dropped the tank and cleaned sock (couldn't get a replacement at the time) fixed other issues and got mpg back, but not this issue-Done 410,000 miles
Replaced injectors with new Bosch and new return lines- Done 440,000 no change with issue, but when I installed them I did the non-turbo side first and ran engine to clear air out and the same noise occurred as described earlier when the new injectors were clearing the air out. Which is why I think it is air in the lines.
Dropped and replaced the sending unit in the tank-Done 442,000 no change with issue
Replaced fuel lift pump, I have an external fuel pressure gauge mounted under the hood to monitor fuel return pressure and was 4 psi before replacement and now 5-7 psi. Done 442,000 no change in issue
Replaced all of the remainder rubber lines on the fuel system under the hood, the two return hoses at the front, the one at the firewall, all the ones connected to the filter housing. the one from the filter housing to the injection pump became wet as i first grabbed it and was very dry rotted, i thank God thinking i had finally found the source of my frustration-Done 447,000 no change in issue.
I have changed the fuel filter many times also and the only mods the truck has is a turbo master from heath and a full mandrel 3" exhaust, I have the boost set @ 10 psi. I do have a boost gauge and EGT gauge.
I plan on keeping the truck for a long time, at least till 1,000,000 mile mark, and at some point what to take it off the road and restore it to its original glory. But right now it is my daily driver. I am leaning to a new IP pump and new Timing set, but don't want to replace all of that and it not be the issue. Any help would be greatly appreciate.
Thanks Blaise