6.5L TD Stalling

[dieselman151]

I realize you have a tech page for stalling, but it does not seem to fit my problem. My problem is that when cold in the morning the motor starts and runs great and will all day without stalling. If started within a few minutes of shutting down, it starts and runs great when warm, However, when shut down for say 20 minutes, although still warm, the motor starts great, runs a few seconds, speeds up for a second or two, then shuts down. Using immediate starter grinding for for a few minutes, the motor begins to slowly fire and slowly starts and runs fine. If left to cool over night, it starts great and will run all day until shut down and allowed to sit for about 20 minutes. That seems to rule out air in the fuel lines and the lift pump. I use 15W-40 oil here in Florida. Could it be that the oil is too thin to maintain pressure (at the pressure switch) enough to keep running when it is warm and sits for 20 minutes? Then start and run great when cold? Would straight SAE 30 fix that?

[Kennedy]

Originally posted by dieselman151:
I realize you have a tech page for stalling, but it does not seem to fit my problem. My problem is that when cold in the morning the motor starts and runs great and will all day without stalling. If started within a few minutes of shutting down, it starts and runs great when warm, However, when shut down for say 20 minutes, although still warm, the motor starts great, runs a few seconds, speeds up for a second or two, then shuts down. Using immediate starter grinding for for a few minutes, the motor begins to slowly fire and slowly starts and runs fine. If left to cool over night, it starts great and will run all day until shut down and allowed to sit for about 20 minutes. That seems to rule out air in the fuel lines and the lift pump. I use 15W-40 oil here in Florida. Could it be that the oil is too thin to maintain pressure (at the pressure switch) enough to keep running when it is warm and sits for 20 minutes? Then start and run great when cold? Would straight SAE 30 fix that? The PMD can fail in many ways. It's not necessarily just hot or just cold, it's thermal changes in many cases. Also, the standing allows it to heat soak. I really don't think it's the OPS as the 6.5 will operate perfectly fine without a lift pump until you load it hard or introduce a leak.

I would say FSD Coler kit time provided you have checked for codes. Adding this kit is something that should be done anyhow IMHO so you are not throwing unnecessary parts at the vehicle.

For future reference, model year/vehicle specs is always handy for troubleshooting.

15w40 is the oil that I would stick with.

[arveetek]

I'm assuming you have a '94 or newer truck.

I agree with Kennedy, it's probably the FSD. My '95 Tahoe was doing nearly the same thing when I bought it. If I started it in the morning and never shut it off, it would never stall. However, if I let it sit for a while, it would stall several times and then go on working. When the engine was off, engine heat would soak into the FSD and short it out. After moving again, it would cool off enough to function right. A new FSD mounted on a remote cooler has cured all my problems.

My lift pump wasn't working at all either when I got the truck. However, that didn't cause the stalling problems. It ran fine, except for some stumbling at full throttle. The failed lift pump/OPS system did shorten the life of the FSD, though, by not running enough fuel through the injection pump to keep it cool.

The best way to check the lift pump operation is to start the engine, and then open the fuel filter bleed valve on the front of the engine. The engine should stay running, with fuel squirting out the hose. If the engine immediately dies and no fuel comes out, then you know the lift pump ain't working.

Oh yeah, stay away from SAE 30 oil which probably isn't rated for diesel use anway (no CH or CI ratings on the bottle). Stick with the 15W40 oil. The engine oil wouldn't have anything to do with this problem anyway.

Casey

[Barry Nave]

And this problem will only get worse with time. Happend to me also years ago, even had a FSD cooler installed. (intake mount) Open hood to find what might had happened that truck would not restart. Truck sat for awhile for lumber to be loaded. Leaned, once the hood was open the cooler cooled along with the FSD and truck stared and all was well,it soon became worse in a short time. If it was hot out now the truck would stall running.

[adamcortell]

I wouldn't rule out the OPS. Last summer my truck was doing the exact same thing. I checked the lift pump and had 5+ pounds. Only would hesitate/stumble/stall on a warm restart. I thought PMD PMD PMD. I got the dealer convinced (still under warranty) and they replaced it for me. They even put it on the heat sink I provided. Next day same problem, hesitating/ stumbling/ stalling on warm restart. I replaced the OPS (32$) and it has run great since. I think the OPS was not functioning on a warm restart. Unfortunatley I did not have a fuel pressure guage set up to monitor fuel pressure during a stalling episode to help verify this theory.

[dieselman151]

Thanks guys, you have helped tremendously. Any particular FSD cooler kit that is the favorite and easy to install? Where can I get it reasonable? I found that Diesel engines are NOT as easy to work on as gasoline, at least not for me. This forum was a wise investment for me.

[Barry Nave]

dieselman151
Go to: my profile just under New Topic. There you can do a Sig. profile about your truck. Year,make,modle and if you have done any Mod's to the truck or may it just be stock.
Now we will know a little more about your truck.

[Kennedy]

The Original FSD Cooler and all the associated parts needed can be found on my site Under 6.5 Parts/FSD Cooler.