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My 1995 Dodge Ram 2500 4x4 Automatic 12V Cummins, unmodified, 186K, has been sitting idle for about six years. Brake lines had rusted out, etc. I started it up from time to time, but didn't drive it. I have gotten back to it recently and replaced the brake lines, replaced the fuel lines along the rail with hoses, changed oil, fuel filter, tabbed the KDP, etc. Saturday I took it out and ran it around 10 miles at speeds up to 65, got it up to normal operating temperature, and all seemed well. Tuesday I decided to drive it to work, stopping to add 10 gallons of fresh "premium" diesel fuel. It's eight miles to the station, and the truck ran fine and up to at least 60 on the way. The station is by the highway and is a truck stop. I got on the highway, got up to about 70, and began to feel a rythmic drag - release, drag - release. Slowed down a bit, but still felt it. Came to a light, stalled when I let off the pedal. Started up again fine, proceeded through some lights, stalled at the next red one. Tried shifting to neutral before the next, but even that didn't work. It started to be harder to start the truck too, taking longer to crank. Finally it died at an intersection. It would start, but might or might not stay running, and as soon as put in gear, it would die. Sometimes giving it more pedal would not do anything, but if I held the position for a few seconds, the engine might then surge up in RPMs. I was able to get out of traffic, but that was it. Had to have it towed home. While I was waiting for the tow truck, I checked for leaks and such; didn't see any drips but I did detect some diesel smell.
When I got home a few hours later, the truck started normally, idled normally, and I was able to move it around in the driveway.
Tomorrow I will check more thoroughly for leaks, check for water in the filter/separator, check for air at the bleeder screw, and perhaps add some fuel conditioner. However, I have a WIF sensor and no light appeared on the dash, and I bought the premium fuel because it already has some of the conditioning additives.
Is there anything else I should check, especially if I don't find any fuel or air leaks? The problem is a bit mystifying, because the truck was running fine on the old fuel (which had conditioner added recently). My working notions are (1) maybe adding the new fuel stirred up something from the bottom of the tank, or (2) there is some problem that only shows up once the engine is fully warmed up. I think (1) is unlikely -- I did have the tank out when I replaced the brake and fuel lines, and it didn't seem dirty and there was no obvious water. I think (2) more likely, maybe I'm getting some connection expanding as it heats up and leaking a bit. But at this point I have an open mind and just need to know what else I should be checking. Would appreciate any advice / ideas.

johnh

sounds like the fuel filter got plugged after you put fuel in it!

Robert Rausch

Definitely change that fuel filter.

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That's a possibility, but two things don't seem to fit well in my mind. First, the filter is new and has maybe 25 miles on it. What would account for such a rapid plugging? Second, if the filter was plugged enough that I couldn't move the truck or keep the engine idling before the tow home, why would the truck start, idle, and move normally in my driveway a few hours later?

Robert Rausch

Algae in the fuel would plug it up fast.

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I drained some fuel from the filter. It looked good, no signs of water or contaminants. I noticed some possible signs of a leak that would drip around the starter, but I wasn't sure if I had just done that when I drained the filter. I cleaned the area up and went for a test drive. Some of it was at WOT / high speed, and the problem did not recur. Got it home, checked the trans fluid (good), and checked for fuel leaks. There does seem to be a leak coming from the WIF sensor / drain valve assembly. But again, I don't know if it only started leaking after I used it. So I'll pull the filter and see what I can do about that. Let's say it had been leaking the other day -- would that explain the symptoms? Seems more like air would have had to get drawn in rather than fuel leaking out ...

Robert Rausch

I've had a bad leak at my fuel filter and I figured it out because I could see fuel streaming out onto the ground when I stopped at a rest stop. The truck ran fine both before I fixed the leak and afterwards.

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After further investigation, the WIF drain is not leaking. Instead, there is a leak coming from the fuel pump where it meets the engine block, at the bottom, somewhat pointy end of the pump mounting surface. It's not a fast leak. I caught a few drops and it was definitely fuel, not oil. When I look at the design of the pump, it does not seem like it could leak there. Leaks from the plunger would go into the engine, and, I assume get fuel into the oil. I see on the pump diagram that there is a weep hole in that area -- maybe it's that. Consensus seems to be if it leaks there, the pump is toast.
If it can't leak there, maybe a leak from the top outlet port, inlet port, or primer button could run down the pump and appear to leak from that spot, but I don't see evidence of such leaks yet. (Hard to get light & mirrors into there.) Perhaps there is even one spot on the fuel heater whence a leak could run over to the pump.
Anyway, I guess I'll replace the pump ...

1320Fastback

Oil level on dipstick is?

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The oil level is normal, and it did not smell like diesel. I removed the lift pump. It didn't look like it had been leaking from the weep hole. It looked like it had been leaking down from the block side, through the gasket, to the lower tip of the pump. Again, it seems strange -- it seems like a leak from there would be an engine oil leak. But back when I found the leak, I caught some of it and it was definitely fuel. My guess is that piston o-ring was leaking, allowing some fuel to travel down the bore. It would then run down the "web" that supports the bore from the bottom, degraded the gasket, and leaked through. But before it leaked through, I wonder how much fuel got into the engine!

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Does anybody have a source for new hard lines, hose-to-preheater and pump-to-filter? The pump-to-filter line is the most important. (I don't want to delete my preheater. I do understand that if I can't find a line, it's possible to run the fuel supply hose directly to the preheater using an appropriate barbed fitting. Not sure if there's an aftermarket alternative to the pump-to-filter line, with the fancy banjo fitting and the manifold drain coming in, etc.)

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Annoying. Guess I have the fuel elbow fitting screwed into the lift pump one rotation more than on the old pump. Now I cannot fit the fuel filter on, because the WIF sensor doesn't clear the elbow hose. But now that the pump is on, all hooked up and sealed with Permatex #2, I don't want to mess with it.

I have been running FS19519 filters instead of the FS1253. It was always a tight fit, but they did fit. I liked the "larger dirt holding area and ... higher flow rate", as Fleetguard says, plus it is a 10 micron stratapore filter while the FS1253 is a 20. Looking around the web, I see others have encountered this problem independently of replacing their fuel pumps. Some cut off part of the WIF drain, some try installing the filter dry, then the drain. As I can't confirm that any other filter 10 microns or finer will actually fit, I will try these approaches.

Moral of the story is treat the fuel elbow fitting like a tie-rod end -- count the threads showing and duplicate that with the new one.

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Ok, it was NOT me, it was the pump. The new pump body is 5/8 inch shorter than the old one from its outlet port to the elbow fitting. It doesn't look like the FS19519 will work at all with the WIF sensor. So, I have two questions:

1. Is there a "pipe plug" that fits the sensor hole in these filters? If so what size -- I gather it is not anything standard. Or do I have to make one from an old WIF sensor?

2. Is there a SHORT (less than 4.5" long) fuel filter that fits, has the sensor hole, and is 10 micron or better? FS1253 is about 4.5" long, but is a lousy 20 microns.

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Well, in case anyone is interested or runs into similar problems, the answers I have been able to find are:

1. Can't find a readily available plug for our filters, although there are places that sell them for Duramax. Our thread size is 1 1/4 - 10 UNS 2A. One could be made from an old WIF sensor, however, it might still be too long to clear the obstructions, depending how much of the body is needed to keep the spring-loaded drain valve closed ... I haven't explored sealing it.

2. I have found that Luber-finer (also Champ and associated brands) LFF3581 (4.37 inches tall, 10 micron) and Donaldson P550931 (4.46 inches tall, 10 micron) are candidates. I've ordered the LFF3581. Not strictly necessary, I'm sure, since Cummins does specify the FS1253 20 micron filter for these trucks. But if they call the FS19519 an "upgrade", isn't the FS1253 a "downgrade"?

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Update: So, after not using the truck for several months, I am back to my original problem! Took it out today, it ran fine, until after it reached operating temperature. Then it started bucking, stalled a couple times at stops. I got it home and partway down the driveway, and it stalled. I could still start it, though it was a hard start, but it would stall when placed in gear, or when allowed to idle (i.e., foot off the accelerator). I tried again a couple hours later and it was still running too rough to move it. I'll try again in the morning. I did not see any leaks, I got fuel out of the top of the filter housing when pressing the primer button.
To recap, fuel hoses from the tank to the engine hardlines were new last fall, along with fuel preheater, lift pump, and filter. The truck had been running fine after those repairs. I am wondering if there's something about not running for awhile that leads to this. Not running for awhile *plus* getting up to op temp. One diesel mechanic speculated I might have an injector sticking open sometimes.