12V problem, rough running, dies

[raxley]

I have about 320,000 miles. I've had it since about 190,000. I put on the pump springs (that w/o would cut off fueling at 2750 rpm) and I put the 60# springs in so it will rev past 2750.
Previously it was used to pull a 5th wheel. I took the 5th wheel hardware out of the bed when I got it.
I now have a problem with rough running and it dying until it was warmed up. It started right up, but in a few minutes, after driving it for a few blocks, it would start idling rough, and sometimes die. If it died, it took several tries to start it up. When it was totally warmed up, it went away. Now it really doesn't go away when it warms up. I've learned to keep it running, but obviously I want it fixed
I have an appt Tuesday next week, and I hope to find out then what is wrong.
If it needs the head pulled because a valve or worn out cylinder (and since I've had it, when it is started cold, a pretty big puff of black smoke would come out, and then it was fine) I'd like to have all the cylinders replaced as well as another (new) head. I want to put towing twins on, and I want it running well.
With a "in chassis" overhaul, you can replace the rod and main bearings, can't you, by unbolting a section of frame?
Can I have it overhauled w/o pulling the engine?

 

[Signal73]

There’s a lot of things to check for that issue. You haven’t really mentioned much as far as maintenance goes, fuel filter and pre filter for starters. Air filter. Lift pump output. Overflow valve. Condition of fuel lines including the elbows on top of the fuel sending unit. Slipped timing. Sticky fuel rack in the injection pump. Your symptoms don’t jump out to me as a worn out rotating assembly. Use caution as to what your mechanic recommends. Make sure he knows proper diagnosis for this engine. As the trucks age the modern mechanics may not know the diagnostic flow chart because they can’t plug into the obdII port and get a computer readout as to what’s the problem.

 

[GAmes]

Jumping to a rebuild question without diagnosing the problem is counter productive. Do you have gauges, specifically fuel pressure? Have you checked the pre-filter? Does it start on the first revolution with a little pedal? 320k is nearing the life expectancy of stock injectors, although I'm sure they are not your problem.

To answer your questions, the 5.9 is a parent block engine, the cylinders do not come out like a big diesel. Attempting to inframe a rebuild would be an exercise in futility. You might be able to pull it off if you have patience and enough tools but the result would be an engine that wouldn't last long. Time wise it would definitely be faster to pull it right and rebuild it correctly.

 

[raxley]

There’s a lot of things to check for that issue. You haven’t really mentioned much as far as maintenance goes, fuel filter and pre filter for starters. Air filter. Lift pump output. Overflow valve. Condition of fuel lines including the elbows on top of the fuel sending unit. Slipped timing. Sticky fuel rack in the injection pump. Your symptoms don’t jump out to me as a worn out rotating assembly. Use caution as to what your mechanic recommends. Make sure he knows proper diagnosis for this engine. As the trucks age the modern mechanics may not know the diagnostic flow chart because they can’t plug into the obdII port and get a computer readout as to what’s the problem.

Thanks for your reply.
I don't know the maintenance before I got the truck (190,000 miles) but it has always had a good clean air filter (I have a BHAF with a outer liner) I've always changed the oil around 6000 miles. I don't tow except for a trash trailer occasionally. I use the truck for transportation for me and my carpenter tools.
It has a pyrometer and boost gauge. At one point, it had a fuel pump gauge that was installed close to the lift pump. The fuel filter is around 10,000 miles old IIRC. I could put the fuel pressure gauge back on. I replaced the fuel overflow sometime back, its fairly new, a year or 2 old. It does act like it might be a fuel problem, when it dies, it will be hard to start for several tries, and this never happens, it starts easily.
What is the pre filter? I modified the fuel heater, I cut most of it off, and left the part that fits against the cylinder block intact. The fuel lines in the engine compartment are pretty new. I haven't checked the lines going to and coming from the tank.

 

[raxley]

Jumping to a rebuild question without diagnosing the problem is counter productive. Do you have gauges, specifically fuel pressure? Have you checked the pre-filter? Does it start on the first revolution with a little pedal? 320k is nearing the life expectancy of stock injectors, although I'm sure they are not your problem.

To answer your questions, the 5.9 is a parent block engine, the cylinders do not come out like a big diesel. Attempting to inframe a rebuild would be an exercise in futility. You might be able to pull it off if you have patience and enough tools but the result would be an engine that wouldn't last long. Time wise it would definitely be faster to pull it right and rebuild it correctly.

Thanks for your reply. I used to have a fuel pressure gauge that was mounted close to the lift pump. I can put it back on. I'll look for it tomorrow. It always immediately starts right away, when cold. Lately, before it's warmed up totally, it would start to run rough, and I'd have to keep the idle high to keep from stalling. It's been getting worse and worse.
I thought that if you melted a piston, that you could just replace the cylinder without pulling the engine. You had to pull the head, of course. Am I wrong about that?

 

[petersonj]

thought that if you melted a piston, that you could just replace the cylinder without pulling the engine.

B series Cummins engines do not have cylinder sleeves.

- John

 

[GAmes]

You did yourself no favors by cutting the spacer from the fuel heater assy and discarding the heater portion. Below the heater was the pre-filter which is the second line of defense from crud getting sent to the injection pump. The first line is the in-tank screen mounted to the fuel canister. I suggest you remove the inlet line to the lift pump and check it, it might be clogged.

 

[Signal73]

I’m wondering sticking rack in the injection pump. Some have diagnosed by directing a solid stream from the garden hose onto the pump when it’s hot. That cools the pump down and if that solves the issue there’s your problem. Not definitive but a tool in the toolbox.

 

[GAmes]

I’m wondering sticking rack in the injection pump. Some have diagnosed by directing a solid stream from the garden hose onto the pump when it’s hot. That cools the pump down and if that solves the issue there’s your problem. Not definitive but a tool in the toolbox.

Good call, but it is the plungers that stick, not the rack. Pouring cold water over the IP is the correct troubleshooting procedure. If the engine smooths out it is time for an IP repair.

 

[Signal73]

Good call, but it is the plungers that stick, not the rack. Pouring cold water over the IP is the correct troubleshooting procedure. If the engine smooths out it is time for an IP repair.

Thanks for the correction

 

[BigPapa]

He said when this started, it was happening BEFORE it gets warmed up.

Have you done any work to it lately? What's your idle speed in neutral and in drive with the A/C or defrost on?

 

[GAmes]

He said when this started, it was happening BEFORE it gets warmed up.

First post. "Now it really doesn't go away when it warms up."

 

[BigPapa]

First post. "Now it really doesn't go away when it warms up."

Correct, but that’s where it started.

 

[raxley]

I'm wondering if what I did to the truck about 5 years ago is the problem or contributing to the problem. I put in this in cab control of the AFC called AFC live
https://powerdrivendiesel.com/produ...mot_tcid=32951660-b5c7-4127-97c1-ae38e18747e2

It lets you make adjustments to the AFC without opening the hood. I never really got it going great, and I'm not sure if it is even working now. Twisting the dials doesnt seem to do anything anymore. According to installation instructions you remove the fuel plate. Now, they will sell you a replacement foot to replace the stock foot, but you still don't have a fuel plate. They didn't sell the replacement foot when I bought it, but now I can't buy the foot because California doesn't allow them to ship it here. Apparently I can't even get a 4" exhaust system shipped to CA, although in 1994 they didn't have any smog stuff on my truck.
I'm wondering (since I heard people say to not remove the fuel plate now) if I increased the wear on/in the p7100.
I'm at a diesel shop in Shingle Springs now (Infinity) and they don't know anything about this thing. Maybe, if they can't fix the problem, either I or they will return it to stock and see if the problem goes away.

 

[raxley]

The AFC has never been messed with until me. It had the wire tamper thing on the AFC, and of course I've removed that.
It's a 160 hp model, so it's pretty slow though.
I did put on the different fuel pump springs so it fuels past 2700 rpm, and I put on the Pac Brake 60# springs so it can rev past 2700 safely, but i never do that because there is really no power up there for me because everything else is stock.

 

[GAmes]

Have you tried pouring cold water over the IP when it is running rough?

 

[raxley]

It runs rough intermittently. I don't think I'd be able to get out of the truck and do that before it died. I've started driving with both my feet so I can keep the engine running (if it starts running badly) and still brake.
I am getting the truck back from Infinity now. He found that my turbo has a little play and also doesn't turn perfectly. You can BARELY feel the friction change a little when you turn it by hand. It's very, very faint. I have a hole in my exhaust before the muffler, and he thinks the two things combining might be something to think about. He didn't have the motor act up on him although he drove it around for 15 minutes.

 

[raxley]

Is there some damage/wear I could have caused by taking the fuel plate out?
Why have I heard not to take out the fuel plate, do you know?

 

[GAmes]

If the turbo blades don't touch the housing a little lateral play is normal. Should be no in and out play. A hole in the exhaust causing the engine to run poorly? I hope you didn't pay that hack a lot of money.

The fuel plate is an internal stop. You substituted the AFC live gizmo in it's place. Will it cause damage or wear? I doubt it but it is painfully obvious you wasted your money when you bought it.

To be clear, the engine runs rough when it is at operating temp or when it is cold, or somewhere in between?

 

[BigPapa]

I would get it out of that shop. All due respect, they may be a great shop, but if they know nothing about the Cummins, they're going to spend your money unnecessarily.

Did I miss your answer about your idle speed? You did say it's dying at idle, right?