Surging

[51Hunter]

Need advise and/or opinions. 2004 2500HD 135K miles. I recently 1 1/2 yrs had all injectors replaced runs great. then 1 yr later had fuel issues as in lack of and dyeing while driving. Found the fuel lines and cooler rotted out. Had those replaced front to back and new fuel filter. Pick up the truck and within a mile find out it surges at idle. Never did this before the fuel line problem. Wondering if junk got into the system and is that the problem or what. From what I read it's the fuel pressure regulator. Ideas?? And trying to find someone to work on it in N/E Illinois? TIA

[DmaxMaverick]

Welcome aboard!

LB7 or LLY (8th digit of VIN, 1 or 2, respectively)? How much surging? RPM's? What's the cadence? Can you see it on the tach, or just feel/hear it? Is the SES lamp on, and if so, have you pulled the code(s)? Tailpipe smoke after long idle? Have you checked for air intrusion (leak in new fuel lines/connectors/filter)? Which fuel filter is installed, steel or plastic? If plastic, they can leak w/o any help (toss it and use OEM or quality steel).

Rusted/rotted fuel lines can certainly cause contamination. Once any part of the system is compromised, the entire system is suspect. You need to get a scanner on it to see what, exactly, is fluctuating and causing the surge (check command/actual pressures), and check for any DTC's active or in history. Any significant pressure fluctuations or inability to reach/hold a pressure will set a code, and likely the SES lamp if it repeats.

[51Hunter]

LB7 surging is about 100 rpm on tach and hear it usually at a idle or stop. No codes No smoke I haven't checked the connections and it's a plastic filter.

I'll have to find a mechanic with a reader. I'll also change that filter never cared for the plastic ones. Any recommendations on how to check for air leaks in the new line connections? I didn't care for the shop that put the lines in but diesel places are hard to find near here. The guy who did the injectors moved on.

Thanks

[DmaxMaverick]

Start with the filter. It may end there. Also replace the fuel filler cap, if it isn't relatively fresh. They're cheap, but must vent properly or they can cause running issues (such as surging).

If not, install a length of clear hose at the filter outlet, looped upward so it will trap air (hose clamps and a barb coupler). Vinyl hose is fine for the short use period. The key is getting it sealed. Don't try this with weak hose and a well-used filter (it can collapse the hose under suction). The OEM fuel system is suction from the tank to the engine (no fuel lift pump). Purge all the air out of the filter and clear line, then start and operate normally. If it's passing air, it will trap in the hose. If it's a major leak, it will show immediately. A little air is not an issue, but if it seems like a lot, it could be causing an issue. The hose from the filter housing to the CP3 (high pressure pump) is one piece, so if it's undamaged and secure at both ends, it shouldn't leak at all. The CP3 pump is very tolerant of air, as it purges while operating, but too much air can pass, and allow running issues. Beyond that, more air can cause it to lose prime, and it is not self-priming (the reason you have to pump up the fuel to get it to run).

If you have an air leak, that's where the fun begins. Start looking at the most convenient locations, and work toward the most difficult. Closer to the tank may require removing the bed. Don't simply drop the tank, as that changes the environment of the lines. A simple place to start is to pressurize the fuel tank. About 5 PSI is all that's needed. You can install a tire valve into a fuel filler cap (you should have an extra, at this point). Put the pressure on it, wait and watch. Most of the time, a leak that lets air in, will let fuel out. Sometimes, it doesn't work that way, and it won't leak fuel out under pressure, while allowing air in under vacuum. Still, it's the simplest method to start once you determine there's a leak.

[51Hunter]

Thanks for the tips. I'll start 1 at a time. As I worked for Ma Bell I have several size cable caps which have a air valve in it and hose clamp on. I've done this on my diesel ford tractor before. I'll try that as well. I kinda suspect the new fuel lines as the problem started after those where placed but will work on the filter first. If I figure it out I'll let you know. Thanks again

[51Hunter]

Now I haven't had time to trouble shoot due to freezing weather. My question is I'm having trouble finding a metal fuel filter around here. Do you have brand name and part number for the filter. TIA

[a5150nut]

Now I haven't had time to trouble shoot due to freezing weather. My question is I'm having trouble finding a metal fuel filter around here. Do you have brand name and part number for the filter. TIA

I run Donaldson filters and like them. Order on line or from a truck parts supply.

[DmaxMaverick]

The part number is the same, since day one. The design, internal and external, changed over the years. I prefer the first generation single element filters, but I use it essentially for a pre-filter for the Mega Filter I have. They are less restrictive and last longer, for me, but are scarce any more. There's only a couple labels on the plastic versions of the same filter. Wix and another I don't recall. Napa only carries the plastic filter (Wix or Napa Gold, which are the same). Autozone lists only the steel filter, and others list both.

[51Hunter]

Thank You

[CoyleJR]

John Kennedy at Kennedy Diesel sells steel housing Baldwin BF46062 filters for my 06 LBZ. He has quick service and is an advertiser on the Diesel Page.

[51Hunter]

Thanks for the brand and #

[51Hunter]

A huge Thank You to all especially Duramax Maverick . The temp got up to 50+ yesterday so I changed out that plastic fuel filter. PROBLEM SOLVED

[DmaxMaverick]

That's great! Most seemingly big problems turn out to be simple little gremlins.

[Kennedy]

A huge Thank You to all especially Duramax Maverick . The temp got up to 50+ yesterday so I changed out that plastic fuel filter. PROBLEM SOLVED

Line #7 from my Fuel systems recommendations email: The black plastic filters should NEVER be used. They are sub standard single layer media and also prone to leaking.

[DmaxMaverick]

If not for the plastic, I'd run single-media filters. If I could, I'd buy up a bunch of the original Parker-Racor single-media filters. The late dual-media filters begin to restrict too early (although not near their usable life), and air-lock the KD Mega. They simply don't flow as well. I know there's a fix for the Mega (not interested), and lift pump(s) are also an option. The issue just hasn't made it far up the list, yet.