Cummins 5.9 12 valve towing issues

[Scepter40]

The other question I didn't think to ask is what is your boost pressure is doing? I would suspect that you're not getting any boost and if that's the case, then that points even more to lack of fuel (filters). If that doesn't fix it, then I'd suspect a fuel pressure and/or supply problem. Culprits are lift pump, overflow valve, boost reference line on the AFC, AFC itself.

[followingsea]

Originally Posted by LargeMarge

.
Different engine.
Nothing you wrote is applicable to the Cummins 12-valve mechanical.
Nothing.
.
.....
.
.[/url]

This why it helps people trying to help people to provide information about thier rig.

Concerning fuel filter: The first thing I did when my MH was new to me was change the filter and carry a spare set. The first thing I did when stuck in the middle of nowhere Idaho, was change the filters but that was not the problem.

I now have a fuel pressure testing kit and also have a permenetly installed gauge.

If you tell me your filters are 4 years, change them and buy a lotto ticket.

[followingsea]

Originally Posted by windsorbill

followingsea,
"As a point of refernce, hit the scales on my last trip. MH and TOAD came in at 16,800 #. My ISB with a BanksPower pack is rated at 300 hp."



Under 17k including toad seems light for a DP, unless there is helium in the tires.

Maybe a typo?

You may be right. I was measuring each axel to make sure the tires were inflated correctly.

I wrote down total = 1850 and tow dolley = 3050

300 # of white cermaic tile was no longer in the kitchen but in the TOAD on the way to the dump.

[bpu699]

Originally Posted by followingsea

This why it helps people trying to help people to provide information about thier rig.

Concerning fuel filter: The first thing I did when my MH was new to me was change the filter and carry a spare set. The first thing I did when stuck in the middle of nowhere Idaho, was change the filters but that was not the problem.

I now have a fuel pressure testing kit and also have a permenetly installed gauge.

If you tell me your filters are 4 years, change them and buy a lotto ticket.

Share more on the gauge…

I was thinking of putting an inline vacuum gauge as the fuel filter should have negative pressure.

[followingsea]

Originally Posted by bpu699

Share more on the gauge…

I was thinking of putting an inline vacuum gauge as the fuel filter should have negative pressure.

This another case of what engine you have and the arrangement of filter on your MH.

The first thing I learned is changing filters is not all that easy the first time.

Then I learned about lift pump failure and how it could damage the injection pump. Did a lot of reading and decided to put a second lift pump between the fuel tank and first filter.

So both of my fuel filters are under a small positve pressure. The engine mounted filter housing has a port downsteam for venting.

I installed this gauge at the fitting. https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1

Since I do not drive enough miles to expect to have change a filter based on miles, the guage is not how I would do if I was drivng a lot.

So before starting out in the spring, lift up the bed to get access to the engine. Bump the ignition, key to check to see if the lift pump runs for about 30 seconds on my vintage of the ISB. Then I check pressure with the engine running.

Lots of discusstions of lift pumps for different engines to search for. I recomend at least carring a spare lift pump since they are not that expensive. Adding a second pump and a guage has provided me with less to worry about.

[Scepter40]

By far the easiest way to install a fuel pressure gauge on a p-pump is to drill and tap a 1/8” pipe thread into the head of the banjo bolt for the fuel feed right on the side of the pump. Then run a line to a glycerine filled gauge using a needle valve. The mechanical lift pump thumps pretty hard, so it’ll destroy a gauge in short order if you don’t. Then just crack the needle valve enough to get a reading. You will probably want to get an adjustable overflow valve as well to keep your fuel pressure up. Here’s an adjustable one that I run on my 12V:

https://www.torkteknology.com/cummin...rk-tek-ofv010/

I find that the stock mechanical lift pump works fine with no issues and folks have been running them more often than not, especially at stock power levels.

[simplysmn]

Originally Posted by rseibenick

1994 Diesel pusher. P7100 pump.

You should also be able to turn it up more ? Same basic engine as the trucks have?

[followingsea]

Originally Posted by Scepter40

....

I find that the stock mechanical lift pump works fine with no issues and folks have been running them more often than not, especially at stock power levels.

I would have to agree that an 12 vdc pump lift pimp controlled by computer seems like a violation of the KISS principle mechanical lift pump.

My first stab at relieving injector pump aniety was with a glow shift guage that I could monitor going down the road using adabptors:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Later I replaced the sending unit with a guage mounted on the banjo fitting. No drilling was required.

My MH is coming up on 200k miles and have not had a lift pump issue in 30k miles.

[Scepter40]

Originally Posted by simplysmn

You should also be able to turn it up more ? Same basic engine as the trucks have?

Yes, should be the same “ish” configuration, save some differences. I have a 12V from a pusher in my Ford Excursion (swapped from a 6.0 power stroke). The main difference in the injection pump is that I have 11mm barrels and the dodge version has 12mm barrels (there are also 13mm barrel versions out there). Most, if not all, folks who flow test and rebuild p-pumps won’t touch an 11mm pump. Seth Farrell is the premier pump builder and he won’t touch one. I took mine to Bosch and they wouldn’t even take it apart to check it and instead gave me a $4K estimate to rebuild stating it was likely that it was a bad pump because it sat for 10 years in a barn (it wasn’t and runs just fine). To my knowledge they didn’t even test it. Most anyone with a flow bench won’t put any pump on without rebuild first due to risk that it’ll mess up their bench. I digress.

You can do work to the AFC and put governor springs in to get higher RPM, install a Mack rack plug, replace the diaphragm washer with a flat one, and adjust the pre-boost fuel (more or less black smoke). I will say that without injectors, you’ll only get so much out of it. Delivery valves are another fuel delivery mod. But, once you get that far, with new injectors, you also need to think about air, which means a larger turbo. It’s a slippery slope. I did all the free pump mods and a set of 5x.012 injectors and have more than enough with stock air to get me moving in the X with any trailer I’m willing to put behind it.

Anyway, none of that matters if the OP’s fuel filters are clogged.

[LargeMarge]

Originally Posted by Scepter40

... I digress.

...work to the AFC...
...governor springs in to get higher RPM...
... install a Mack rack plug...
...replace the diaphragm washer with a flat...
... adjust the pre-boost fuel (more or less black smoke)...
... injectors...
...Delivery valves...
...larger turbo. It’s a slippery slope...

Anyway, none of that matters if the OP’s fuel filters are clogged.

.
Mod away... up to the limits of other components:
* trans
* U-joints
* frame
* mounts
* cooling system...
... and the other end of the scale
* brakes and suspension.
.
We operate a small organic teaching farm near the outskirts of Eugene, Oregon.
We have a half-dozen Dodge Cummins 12-valves for delivery and farmer markets.
We need reliable, we need mpg.
We keep our rigs stock.
.
Our ExpeditionVehicle Cummins 8.3 12-valve is stock.

[simplysmn]

Originally Posted by Scepter40

Yes, should be the same “ish” configuration, save some differences. I have a 12V from a pusher in my Ford Excursion (swapped from a 6.0 power stroke). The main difference in the injection pump is that I have 11mm barrels and the dodge version has 12mm barrels (there are also 13mm barrel versions out there). Most, if not all, folks who flow test and rebuild p-pumps won’t touch an 11mm pump. Seth Farrell is the premier pump builder and he won’t touch one. I took mine to Bosch and they wouldn’t even take it apart to check it and instead gave me a $4K estimate to rebuild stating it was likely that it was a bad pump because it sat for 10 years in a barn (it wasn’t and runs just fine). To my knowledge they didn’t even test it. Most anyone with a flow bench won’t put any pump on without rebuild first due to risk that it’ll mess up their bench. I digress.

You can do work to the AFC and put governor springs in to get higher RPM, install a Mack rack plug, replace the diaphragm washer with a flat one, and adjust the pre-boost fuel (more or less black smoke). I will say that without injectors, you’ll only get so much out of it. Delivery valves are another fuel delivery mod. But, once you get that far, with new injectors, you also need to think about air, which means a larger turbo. It’s a slippery slope. I did all the free pump mods and a set of 5x.012 injectors and have more than enough with stock air to get me moving in the X with any trailer I’m willing to put behind it.

Anyway, none of that matters if the OP’s fuel filters are clogged.

Contact power driven diesel out of Utah. They specialize in p7100 stuff. I know 1 of the guys who works there. He's doing a 1000 hp engine build right now. I'm a ve pump guy I'm happy with my little 450hp ve engine in my 85 crewcab. Not bad for a engine that started with 160 hp stock.
PDD should be able to give you a better answer.

[Scepter40]

Originally Posted by LargeMarge

.
Mod away... up to the limits of other components:
* trans
* U-joints
* frame
* mounts
* cooling system...
... and the other end of the scale
* brakes and suspension.
.
We operate a small organic teaching farm near the outskirts of Eugene, Oregon.
We have a half-dozen Dodge Cummins 12-valves for delivery and farmer markets.
We need reliable, we need mpg.
We keep our rigs stock.
.
Our ExpeditionVehicle Cummins 8.3 12-valve is stock.

Absolutely true!

One other thing I forgot that makes all the difference in the world (but to your point stresses components) is timing. I want to say I set mine at 16 degrees, maybe 17. Which, as performance 12V's go, isn't much. But, surely wakes up the stock configuration quite nicely (which I think is ~12).

[Tj2251]

We had a similar situation develop a few years back when going through the Blue Ridge Mountains then noticed that even on flat roads performance was dropping, So I brought it to a local turbo service facility feeling that the turbo was going out,. They checked and found one of the hoses at the turbo was split and negating the turbo's performance. Once replaced it was like having a new coach again!

[Jarlaxle]

Originally Posted by followingsea

This why it helps people trying to help people to provide information about thier rig.

It was literally the thread title.