Community Forums

pawpawboyce · 08-13-2018, 01:01 AM

well, I have now changed all filters including fuel filters on my C7. I fire it up and it runs so smooth for 15 minutes. after I start, I set the idle at 1,000rpm
and it sets there and hums like the day it was new. now it's has only 26,ooo miles. THEN it starts coughing, missing, and finally dies down and then turns off. Some say the high idle has a feature that it will shut down after idleing so long. I don't know. If so, it would seem that it would shut down clean and not cough and sputter. I've owned this coach since 2006 and never had a problem like this. Maybe bad fuel? Help?

CountryB · 08-13-2018, 02:09 PM

If you just changed the filter and this problem started - I would go back to the filters.

Maybe you left the old gasket in place (so you have two gaskets stacked when put on the new filter) so you are sucking air.

Does the engine restart immediately or take some cranking time?

pawpawboyce · 08-14-2018, 05:34 AM

Country B, thanks for the reply. It starts immediately from a cold start and will run 10 to 15 minutes and then choke down like a gas engine running out of fuel.

desertdd · 08-14-2018, 06:40 AM

If this happened after you changed fuel filters, I would say the system has air in it somewhere. I would remove and reinstall the fuel filters and recheck the placements of all of the gaskets. My experience also has been that some aftermarket fuel filters sometimes don't quite fit and allow air into the system. I usually get my filters from Freightliner which are usually Alliance, Donaldson, or Cat. My experience with my C7 is that it is very forgiving and usually works the air out on it's own. I have installed the final fuel filter empty of fuel and it worked the air out in a small amount of running.

pawpawboyce · 08-14-2018, 10:45 PM

My first thoughts was air in the system, but it is hard to reason air since 8 hrs after choke down, it will start right up and sounds great idling for 15 minutes.
Today I ran my generator (cummins 7.5) for about 5 hours with a miss. I just can't explain why it runs so great and then chokes and dies. The engine furl was bought from Cat., the Alliance secondary filter I got from freightliner just like the on that came on the coach in 2006.

Thanks so much for your reply.
Pawpawboyce

pawpawboyce · 08-14-2018, 10:46 PM

Correction ran for approximately 5 hours without a miss. Sorry.

FIRE UP · 08-14-2018, 11:38 PM

Quote:

Originally Posted by pawpawboyce

well, I have now changed all filters including fuel filters on my C7. I fire it up and it runs so smooth for 15 minutes. after I start, I set the idle at 1,000rpm
and it sets there and hums like the day it was new. now it's has only 26,ooo miles. THEN it starts coughing, missing, and finally dies down and then turns off. Some say the high idle has a feature that it will shut down after idleing so long. I don't know. If so, it would seem that it would shut down clean and not cough and sputter. I've owned this coach since 2006 and never had a problem like this. Maybe bad fuel? Help?

Well pawpaw,
A couple of items here. One, we have an '04 Itasca Horizon 36GD with the CAT 330HP C-7 and, I have ran that engine on high idle for up to 30 minutes or more and it has NEVER AUTO SHUT DOWN. So, not sure about that idea of shutting down after a given period of time. None of my buddies that have CATs have ever mentioned anything about it either and, they have idled periods of time too.

Second, based on your description of how it acts, to me, it's hard to pin this issue on "air" in the system. To me, if there was air, it wouldn't run almost at all. Air is air. If it's in the system, then it should be stumbling all the time, not just after a while. If you changed the filters and then started it and it ran for over 15 minutes, that should have been long enough to clear any bubbles in the system you created when changing them. And, if so, it should continue to run.

Third, you said you changed FILTERS, AS IN PLURAL, correct? Am I to take it that means TWO fuel filters? You see, on our '04, we only have one fuel filter but, before my coach and after it, they had two. And, if you have two, do you have a primer in the system, next to the secondary filter? If so, have you tried to use it when your engine died? If you don't have one, then there are other ways to prime the system. Interesting.
Scott

gatorcq · 08-15-2018, 09:01 AM

Agreed about high idle timer - this is a new one.

Have you tried to pull codes?

Another have you pull the connector to the IAP sensor (Injection Actuator Pressure).

Sometimes they become erratic, causing some strange things. Remember,, oil is used to control the injection system (upto 3000 psi).

By removing the connector, is will go into limp mode (1700 rpm). If it continues to run, $160 in parts, 15 minutes change out.

CountryB · 08-15-2018, 02:12 PM

Quote:

Originally Posted by pawpawboyce

Some say the high idle has a feature that it will shut down after idling so long. I don't know. If so, it would seem that it would shut down clean and not cough and sputter.

Some do have an idle shutdown timer. I have a CAT C13 and the manual says this:

However, I agree with you that engine would not cough and sputter - it would shut off cleanly.

pawpawboyce · 08-16-2018, 10:59 AM

FIRE UP my C7 has the one engine fuel filter which is a buggar to get to unless I loosen the bedroom screws and go in from the top and that is just about as bad if you're working alone. On the rear of the coach is another filter OEM perhaps by Freightliner. The brand is Alliance with a water detection screw to release water. This situation is frustrating, if I could drive to a qualified mechanic off I would go. I'm positive it will shut down in route. Towing is so expensive including dropping the drive shaft to avoid transmission damage.

One last thing I haven't done is to drain and clean the diesel tank completely. Only this holding me off on this is I have run the Cummins generator up to 5 hours off the same fuel tank. Thanks to you, Country Bill, gatorcq, desertdd,
for your comments and help. I feel we have narrowed it down to 2 things: An engine problem perhaps caused by electronics or something, or just bad fuel and trash.

CountryB · 08-16-2018, 02:30 PM

I would get a code scanner and see if the engine shows any codes - and you can monitor some of the sensors to see if any look like they are wrong (like engine temp showing 240 degrees when yo know the engine is cool).

If you don't already have real time engine monitoring through built in monitoring like Aladdin or a ScanGauge D, you could add something. But cheapest thing would be to get a hand scanner like https://www.amazon.com/dp/B01N4GH6UZ...v_ov_lig_dp_it.

If you think fuel may be contaminated you could remove the filter again, and dump the contents into a glass jar. Let it sit overnight to see if anything settles out (like water).
It seems that this problem started when you changed fuel filters - so my instinct (as a former mechanic) says to replace those filter(s) again. You may have gotten a factory defect or just messed up the installation somehow. I have been fooled before assuming a new part must be a good part.

Are there any wires or hoses, or such in the area of the filters that you could have pinched or knocked loose? Generally went the engine is running fine, you do something, then it doesn't run fine anymore, you go back to the area you were working at for the source of the problem.

10EC · 09-19-2018, 06:58 AM

Maybe go back where you started.
You may have picked up a (new) bad filter. Sounds like fuel flow issue to me.

Cat filters are high dollar but------

good luck

Cat · 09-19-2018, 07:07 PM

The Alliance filter does it have a water bowl on the bottom? This primary fuel filter is on the suction side of the fuel system- normally. If it does not seat properly it will suck air in slowly until enough air has built up in the system to cause the engine to die. It also takes awhile to purge the air out of the CAT fuel system. When I changed mine after the engine and started and built oil pressure I would take engine RPM up to 1500-1700 and keep it there for 5 minutes, before returning to idle.. The secondary fuel filter CAT one is under pressure so if it not seated it leaks fuel out. Hope that helps, good luck.

Cat · 09-19-2018, 07:26 PM

One other thing came to mind. There are several different Alliance fuel filter some are used as a final filter are 2-4 micron and the fuel is pushed through the filter. The suction side filter have to be in the 10-20 micron range. The fuel pump will not suck the fuel through a high efficiency fuel filter 2-4 micron. It's just to much restriction. Make sure you have the correct filter in the correct location. Just another thought. Safe Travels.