I have a 2002 Winnebago Journey 32t with a 5.9 Cummins 300 hp engine. It generally runs great. But we have had occasion where when climbing, after a downshift at about 2500 rpm, it will misfire, one miss, them about 3-5 seconds later, another. The check engine light flashes so fast when it happens that I could not read what it says. It does not do it at lower rpms or climbing in top gear. About 6 weeks, we did some hills with no issue. This time, the only thing I can thing of that was different was I put about 55 gallons of fuel in it. Is it possible it is bad fuel? I was towing a CRV. Thoughts?
Does your engine have a lift pump that looks like this? If so, you might just need to tighten those 3 lift pump bolts. This will often fix (80% of the time) the air getting sucked into your injection system.
In my coach I need to access go in through the bedroom trap door to access the top my engine... and on the passenger side... forward... is my the top of my lift pump bolts.
Note: You can't see the pump outline from the top of the engine, but the 3 bolts are visible. And sometime you need to move a few hoses out of the way. Just look for and follow your fuel lines into and out of the lift pump.
...If your lift pump bolts are loose, you may put a full turn on them. Just don't over torque them! ...And the good news is you can do this yourself and it will not cost you anything to fix!
...Left unchecked you could end up buying a new CAPS Injection Pump and with installation that could run you over $6,000. (Seriously! Don't drive anymore under heavy loads until you verify you are not sucking air into your vacuum fuel delivery system.)
If you don't have a lift pump like the one in the picture below, which comes off an ISC-350HP Cummins, then you still need to start looking for vacuum leak problems in your fuel lines that run "TO" your injection pump.
Alternatively, some owners find their fuel lines can deteriorate and that decay causes "flappers" to form in the line; and what this "flappers" do is create foam in the fuel that interferes with your injection pump ability to deliver enough fuel to your injection pump. And the simple point about a "engine skip" under load, or when your engine dies after it starts, is that when you don't have enough fuel... you don't have enough cooling... and it's heat the cause your injection pump to fail.
And the better solution to tightening lift pump bolts is to add a FASS or AirDog electric lift pump! Go to IRV2.com and you will find a lot of information on this subject.
If you have a lift pump that looks like this ISB type then you will not have 3-lift pump bolt like the ISC motors, but the same concerns apply:
1) Do you have a fuel delivery problem (low vacuum due to an air leak on the line "TO" the lift pump or "TO" the injection pump)?
2) Do you have a fuel restriction caused by a "Flapper" or other obstruction?
3) What is your fuel pump vacuum?
Question: Do you have a CAPS injection system or a VP44 type?
Get your engine serial number and call 1-800-CUMMINS to ask for assistance. They will take your call and give you very good customer service. As for getting good customer service from a local Cummins shop... not so much!
Note: If you find replacing your fuel filters seems to fix the problem, that does NOT mean your vacuum system is not sucking air. And it may mean your engine is operating on the "borderline" of what fuel vacuum is acceptable. As fuel filters fill up the back-pressure increases and this lowers the vacuum pressure in your fuel lines. The system runs on -5PSI so every psi counts!
* Check all your fuel fitting for air leaks, which is hard because vacuum sucks air into the line so it's not like you can spray the fittings with soapy water. However, the only time your fuel line is pressurized is during those first 15 seconds when you lift pump is turned on. Then you fuel lines will show +15PSI. So this is the time to spray the fitting with soapy water of Windex.
* Another symptom of a boarderline fuel delivery system is called a 1/4 tank problem. This is when your fuel tank is less than 1/4 full... and your engine will start... but then stalls 1 minute later. (Fuel starvation is the reason.)
First you may experience an engine skip... then you will think you fixed the problem by changing fuel filters... and 8,000 miles later the problem will reappear... then you change the filters again... and 5,000 miles later the problem will reappear... then one day with less then 1/4 tank your engine starts and then stalls. ...All of these are symptoms of air entering your fuel delivery line TO the injection pump (CAPS or VP44).
Imnprsd, sorry I have not responded before. I honestly just saw your response. thanks for your detailed response. I currently have the Journey in storage for the winter (gotta love the northeast) but you have given me some things to look at. I am not sure I. An troubleshoot all that you mentioned but I should be able to find those bolts and give that a try. It is pretty intermittent. I am not sure it is still not trans related. It almost feels like it wants to shift and can’t for some reason. It also only does it at between 2300-2500 Rpms so I am wondering if that is a shift point. I think I read that this could be a cause and related to a bad ground and the freightliner dealer had just replace the alternator and fixed a bad ground d and it had not happened before that. I will check both in the spring.
I have had the same problem on my 2002 32T Journey. Climbing a steep grade with a TOAD, downshifts out of OD, 2400-2500rpms, 100% load, CEL comes on and hiccups for a second. This may happen 2-3 times on long steep grade usually when tank is NOT full.
Flagstaff Freightliner saw that it had code 368 (fuel pump can not reach commanded timing), changed the fuel filter and shrugged their shoulders. There is a trouble shooting procedure for that code and I checked the things I could. (lift pump coming on during starter bump, voltage to pump is correct, puts out the right volume of fuel when cycled, no major air visible in fuel). I don't have the fuel gauges to check pressure.
I will check the three bolts on the lift pump. I am suspecting fuel restriction, maybe collapsed line, since this seems to happen at max fuel demand.
Just to be clear, those 3-bolts you want to tighten are only applicable to ISC-350 and ISC-400 CAPS injection type systems from 1998-2004 to the best of my knowledge.
See picture above.
I don't know if the ISB uses this same lift pump? Who can verify this one way or another?
Linear Mode
