I have an 02 Journey with a 5.9 Cummins. Runs great however on a long hill when it down shifts to 5th after a while it develops a quick stumble, just like turning off then on a light switch. Every time it stumbles the check engine light flashes on. It will continue with varying time intervals between stumbles until the load decreases. The other thing it does is on the down side of a long hill where you just are coasting (65 mph or so) with no throttle, the check engine light will come on and stay on until you hit the throttle, then it goes out. Otherwise it runs great. Any ideas? I have changed the fuel filter so it is not that. Also as far as I can tell (and I have looked a number of times) it only has one fuel filter behind the rad... Even had it on a lift to look.

I do have a friend who can hook up to this MH to see what the code(s) are but won't be able to do this for a bit and will likely be using it this weekend.

thanks

What kind of lift pump is on it? The reason i ask is it sounds like it's running out of fuel and a weak lift pump would cause your symptoms.


Joe

Does this 5.9 have a "Pre-Heater" screen next to the manual prime button on the LHS of the engine?
These screens are notorious for plugging up. I think it will take a either 3/4 or 7/8 wrench or socket to remove the cup.

sr4440
Stock lift pump. I am kinda thinking fuel too. But why would it do it during coasting down a hill. Also when coasting there is no engine stumble.

TD3550
No idea, can you give me more details so I can check this. I assume LHS means left hand side, which would be the driver's???

The vp44 fuel pumps are known to go bad. I had to replace mine on a 2003. You will need to capture the code for the exact reason.

quote:

Originally posted by TOP38:
sr4440
Stock lift pump. I am kinda thinking fuel too. But why would it do it during coasting down a hill. Also when coasting there is no engine stumble.

TD3550
No idea, can you give me more details so I can check this. I assume LHS means left hand side, which would be the driver's???

I apologize, Thinking 12 valve. Yours is 24. There is no lift pump (manual) Electronic lift pump only. This video will give you a good idea even tho its in a pickup 24 valve. Electronically self priming system.If you were closer i would hook up the laptop and see whats in the history.
I apologize. Yes, Left Hand Side. These pumps are known to go out. Don't throw $$ at it, have it scanned first.

Find the fuel filter canister and follow the fuel line back to the lift pump is the easiest way to find it. Unless its in the tank.

This message has been edited. Last edited by: TD3550,

How many miles are on it? I wouldn't go to crazy until you pull the codes. Could be Crank sensor, throttle position sensor.

quote:

Originally posted by Sc1041:
How many miles are on it? I wouldn't go to crazy until you pull the codes. Could be Crank sensor, throttle position sensor.

Just over 60K. This also makes some good sense based on what I feel and the fact it doesn't always do it.

If fuel was an issue, power should be off all the time there is high load, and it is not.

A few years ago I did a repair on a diesel Onan in a motorhome with a 5.9 Cummins. A Tiffin

When he came to pick it up he did not get very far and limped back to our place.

We worked on it for a while changing filters and trying some things but as I recall the lift pump went bad.

If you had that problem you would not get very far....he couldn't even make it up a small hill out of our place...

Sounds more like a sensor issue..

quote:

Originally posted by SCDIV1:
A few years ago I did a repair on a diesel Onan in a motorhome with a 5.9 Cummins. A Tiffin

When he came to pick it up he did not get very far and limped back to our place.

We worked on it for a while changing filters and trying some things but as I recall the lift pump went bad.

If you had that problem you would not get very far....he couldn't even make it up a small hill out of our place...

Sounds more like a sensor issue..

And it starts up nice/fast which would also indicate a decent lift pump, right?

I agree that it doesn’t sound like fuel starvation but FYI - my 2004 5.9 (Freightliner XC chassis) has a second in-line fuel filter that is hidden over the rear axle and took about a half hour of crawling around under there just to locate it.

If it is a lift pump it will also be a vp44 pretty soon. Can’t starve them for fuel. You should have an idiot light on the fuel pressure anyway.

When my crank sensor acted up it went into limp mode immediately. Also was hard starting.

If you’re going to keep it for awhile, buy a VMspc. Worth it.

Luckily I was not the one crawling around under that MH trying to find fuel filters and looking at lines trying to find any hidden filters.

I really don't recall how it got fixed or who fixed it. I know it wasn't us.

I assume the owner took it to someone close by for the repair..

I was the one unlucky enough to wrestle with his Onan and that was no fun at all...

I was parked in the stacking field at Maple Grove's nat'l event last month next to that MH and it's owner......

Al,
Billy is correct. My 2004 5.9 had 2 filters on it also. The second one is a pain to see, let alone to change.
Like Billy said, it is above the rear end on the passenger side by the leveling jack up in the frame.

Just an FYI, mine acted like you are describing, but it was NOT fuel related. It was the turbo/wastegate not working properly. It eventually just stayed in limp mode.

As was mentioned, get the codes checked ASAP.

quote:

Originally posted by pentastarrail:
Al,
Billy is correct. My 2004 5.9 had 2 filters on it also. The second one is a pain to see, let alone to change.
Like Billy said, it is above the rear end on the passenger side by the leveling jack up in the frame.

Just an FYI, mine acted like you are describing, but it was NOT fuel related. It was the turbo/wastegate not working properly. It eventually just stayed in limp mode.

As was mentioned, get the codes checked ASAP.

On the second fuel filter, I will have to check again. I will also give Freightliner a call too. Was yours a Freightliner XC chassis?
I had it on a lift so access was not an issue. I was told that it also had a prewired trailer brake plug up front under the dash, that was not there either.

When it cuts out, it is so short time wise so I can't tell what's going on other than it acts just like turning a light off then right back on, its that quick.

Mine is an XC. The filter is an in-line filter and looks kinda like the older fuel injected GM vehicles had. The Wix part number is 33252. I don’t think Freightliner could’ve put it in a more difficult spot if they tried. Mine did have the towing harness under the dash but that was also a nightmare to find! I had to cut and pull down almost every harness under there before I found it and it didn’t have a power wire like it was supposed to, but it was there.

quote:

If fuel was an issue, power should be off all the time there is high load, and it is not

my filter has given me trouble a couple of times and other than the coasting problem it acted like yours.it would get worse the further i drove it and at one point it even got better.as others have said a computer read is essential.

sent you a PM Al

Mine was an XC also.
Sounds like Billy did everything I had to do with mine.
And yes, I would bet you the towing harness is there, you just need to dig deep and basically take the whole under dash harness apart. Mine was buried and way up inside tied together with all the other wires.

When you change the the filter over the rear be prepared to take a diesel bath. You'll only be able to get about a quarter turn on the fittings as the fuel is running out all over you. It's jammed in with all the other lines and wiring IN the C-channel of the frame with not much slack.

quote:

Originally posted by pentastarrail:
Mine was an XC also.
Sounds like Billy did everything I had to do with mine.
And yes, I would bet you the towing harness is there, you just need to dig deep and basically take the whole under dash harness apart. Mine was buried and way up inside tied together with all the other wires.

When you change the the filter over the rear be prepared to take a diesel bath. You'll only be able to get about a quarter turn on the fittings as the fuel is running out all over you. It's jammed in with all the other lines and wiring IN the C-channel of the frame with not much slack.

Frank

I did take the front apart! It is not there. I did find out after the effort that they started installing them about 3 to 6 months after mine was built.....

I will let everyone know about the filter. I will get my Sherlock Holmes magnifying glass out this weekend!!!!! LOL If that dam filter is there, it sound like it's worth gutting it and reinstall it, then get an aftermarket deal that can be located in a much better location!!!