ISC 350 Fuel Question

[Dirtbuster]

The other day I took the coach for a ride. When I started to take off, the engine died, & the CEL light came on. I have done a bunch of reading, & I suspect I might be having lift pump problems. The last trip out in April, this happened once on the way home. I put a new Fleetguard fuel filter on, thinking that might be the problem! It seem it is something else.

What suggestions does anyone have, based on my symptoms. Is there a place to install a fuel pressure gauge, to monitor pressure? Can the gaskets or o rings be replaced on the lift pump? I am going to trace out the fuel lines to the tank, to make sure that there is not another fuel filter, Freightliner does not show one on the ISC350, but that doesn't mean one is not hiding there.

Thanks!

[deandec]

I think the lift pump only functions to get fuel to the injection pump and then ceases operation while the engine is running. At that time the injection pump takes over.

If that is correct, and your engine started and idled ok for a period of time before "starting to take off", the problem must be elsewhere.

I guess the fuel shut down solenoid could be releasing as you increase the rpm's and shutting the fuel off. You could check the electrical connection at the solenoid. (My wire connection was loose and did not allow the engine to start.)

A fuel filter could be partially clogged and starve the injection pump under acceleration. Replacing that new filter would be the cheapest step.

Beyond the above, the only other cause that would be fuel related that I can think of would be the injection pump itself.

Save that for the last thing to check as it is costly.

I would assume that the air filter is still good and plenty of air is getting to the combustion process.

[Dirtbuster]

If I am doing normal driving, the engine runs fine. It is when a take off load is applied, it will bog down ( with CEL light on ). While reading, saw where it is possible for a failed lift pump gasket to suck air. I read that others could go 200 miles, before the problem might occur. The air filter is 7 months old, with 800 miles on it. The fuel filter has 100 miles on it. I will start looking this week, while installing my new surge tank. I hope it is something simple, but with my bad luck?


Thanks

[ua40j]

If you haven't checked the lift pump, it's a good time to look at it. Mine seeped before it started to leak, so I was unable to determine that it was failing until I found pools of fuel under the engine.

On the other hand, if your lift pump isn't failing, the filters are not clogged, there are no breaks in your air charging system and the fuel is fresh, then it could be the injector pump (big $$$$), cracked fuel line (letting air in), or something more sinister and hard to find (not much help there).

I'm betting on the lift pump. Even if it's not leaking when you turn the key on, it still might be letting in air.

[HD4Mark]

We had kind of the same problem with our ISC 350 when we picked up our coach from the dealer on the way home. Fortunately he made good on having Cummins repair it.

Any grade we went up it would stumble like it was losing power. Turned out to be some junk in the lift pump screen. Does your coach have one or two filters? Ours only had one, placed after the lift pump. The Cummins tech told us for some reason Freightliner left off the one before the pump for a few years. We paid the local Freightliner service to install a second one figuring if something was in the tank it was easier to change a filter than clean the lift pump screen. Never had the problem again but it was good peace of mind.

[Dirtbuster]

I changed out my expansion tank today in around 2 hours with no problems, I decided to check out my fuel system. I removed my filter, & saw some flakes of trash in the bottom of it. I also noticed, that I forgot to install the upper rubber seal on the filter housing. I rode down the road to the local Cummins Dealer, to see what he thought. He said leaving out the upper gasket, would make it run terrible. I installed the gasket with a new filter. I finally got it primed, & took it for a ride. I drove around 25 miles with some big hills, & all was good! As I got off the off ramp onto the highway, I started accelerating & the engine started to die. I backed off the throttle, & it slowly picked up power. I don't understand what is going on? I ran a steady 70-80 MPH on the interstate, & nothing happened. I make a right turn & started accelerating, & it loses all power. This does not make since to me? The trash in the fuel filter is not good. I also did not get a chance to trace out the lines, due to weather.

My 1st thought is the lift pump. 2nd would be trash in the tank. 3rd injection pump strainer. 4th I don't want to think about. It looks like I can install a pressure gauge on the filter housing, but I can't see it going down the road. Does anyone else have any other thoughts, with an action plan?

Thanks!

[KIX]

Have you considered a VMSpc........program is free but the data link cables and "interpreter" is about $400. But, with it you can see all sorts of engine activites and read codes, etc. google it for more info

[Dirtbuster]

Quote:

Originally Posted by KIX Have you considered a VMSpc........program is free but the data link cables and "interpreter" is about $400. But, with it you can see all sorts of engine activites and read codes, etc. google it for more info

I have considered one, but I would like to play with one 1st. They look pretty limited, on their troubleshooting capabilities. They show operating parameters, but I am not sure if it is what I want.


Thanks

[KIX]

Quote:

Originally Posted by Dirtbuster I have considered one, but I would like to play with one 1st. They look pretty limited, on their troubleshooting capabilities. They show operating parameters, but I am not sure if it is what I want. Thanks

Maybe you can chat with someone that has had VMS longer than I have but, I think it would be a pretty helpful tool to troubleshoot. After all it will show you (as I understand it) the same info a Cummins shop can see when they hook up to your OBD

[Dirtbuster]

Does anyone have a copy of the Cummins fuel troubleshooting manual. Is there anything that could help me. I also talked with Freightliner Gaffney today, they suggested looking at the throttle position sensor. This is a longshot, but something with easy access.

I cut open the fuel filter that had been on for 100 miles. Other than a little trash in the bottom of the filter, the media looked new looking.

Thanks!

[Airtool]

What year Chassis are you all referring too?
Most of the frieghtliner Chassis come with 2 Fuel filters,that being said around 04 they hide an inline fuel filter along the frame rail-drivers side-right next to and behind the rear axle. Almost impossible to see and not common knowledge to many. from 04 to 06 time frame.
They are small and can plug up in a short time.
Regarding the fuel pressure sensor.There is an add on circuit. Will forward the info. if you would like!
My diesel uses a VP-44 injector pump and if the fuel pressure drops below 5psi.it fries the high pressure pump, a 3 to 4k repair job I can do with out.
I use one because my Diesel fuel system has no OEM pressure monitor.
I use VSMpc and it can monitor fuel flow rate but not pressure,the newer fuel systems my have a pressure sensor that the Software can monitor.
A call to Silver Leaf could answer that question.

Every day is a gift,and if you have not had a bad one! you will never know when your having a good one!

[HeapBigEngin]

Your problem does not sound like a lift pump to me. We had ours replaced on our 8.3 Cummins in our 2003 F/Wood Revolution last July at 36,000 miles....it was leaking badly. I have since learned that this has become a common occurence on Cummins (maybe others as well) with the change to ultra high sulpher fuel. The original main internal gasket deteriorates, and the pump starts to leak. I recall trying to find a gasket kit for the pump, but could not locate one that I was comfortable with....and Cummins no longer offers it. How convenient. So a new pump with new gasket material was installed. Sigh...

I believe the lift pump does one thing....it pressurizes the fuel system at about 5 lbs. psi, I believe, "lifting" fuel from the incoming fuel lines up to the fuel injector pump (which operates at very high pressures). It normally shuts off after about 30 seconds or so when it has done its job. I suggest you turn on your key - but do not start your engine - and walk back to the rear of your coach. You should hear the pump pressurizing....and then you should hear it shut off. Prior to the lift pump replacement, our coach ran great. The pump was still "lifting"....but it was leaking like a sieve.

Is your lift pump leaking?? Not sure what is ailing your coach, but a lift pump with the typical leak should not cause the problems you are having. Can it pull in air? I dunno'. It would likely push out fuel rather than suck in air since it's a pressurized system. And if it lost pressure, it seems a sensor somewhere would turn the pump back on. A good Cummins tech could answer that. Now, if you have contamination that is clogging the pump somehow and restricting fuel flow to the upstream injector pump, then that is a different issue. FWIW, the Cummins tech that replaced our lift pump told me that leaking lift pumps are very common these days and that fuel injection pumps rarely go away.....good thing because they are VERY expensive. Sure hope he's right re ours!!

Please let us know what you find out....Thanks

[Dirtbuster]

I spent some time under the frame rails to day. I can not find another filter anywhere. I talked with Freightliner Tech again today. They said the ISB engine & the Cat engine has 2 filters. They suggested bypassing my fuel tank at the lift pump. Run a temporary line & fuel tank to see if it makes any difference. If it does, start working back towards the fuel tank. There are not any hard metal lines on my coach, only plastic tubing, & fuel hose.

I was thinking I might install a sight glass after my fuel filter, along with a fuel gauge. This would show me if I am holding the required 5 psi, & if there are any are bubbles in the system.

Thanks for the replies & help!

[Airtool]

Over the past 2 or 3 years I have gathered some info. regarding the fuel filters used primarily on the Cummings system.there maybe areas where it could help some Cat systems.
Attached are copies of some of the discussions and information.
The PDF File pictures the locations of the inline filters
#1
> I stopped by Cummins Northeast in Albany NY yesterday on another
> matter, and while there, I mentioned my feelings that the Racor
> Strainer mounted in the Frame rail (on 2003-2005 ISB02 Bounders with
> the Cummins engine) was difficult to get to. He offered a solution in
> the form of a top mount Fleetguard FF105 fuel filter. This is a
> product which meets Cummins specs for the ISB, and can be mounted
> anywhere on the frame using a custom bracket that the filter head
> would mount to. So if you're tired of your Racor, and know a shop thet
> could fabricate the bracket and route the fuel lines to it, take a
> look at the photo in my Hal R. folder in the Photos section of this
> board. As for me, I'm going to hold onto my sight glass a little
> longer. Cummins quoted me a price of $24.00 for the filter and filter
> head assembly, and said extra ff105 filters were currently selling for
> $4.80.

#2
Well, helped another soul for my New Year's good deed. Some fellow I know only
as John called me New Year's Day because his rig dropped to 45mph max somewhere
in Georgia on his way to Naples Fl. and no one could figure out what was wrong
with his rig. He got my number off the web somehow, ans asked for the likelihood
that he had a mystery filter. I determined that he had bought the rig in '04
new, and knew nothing about a second fuel filter or strainer. Since he fell into
the 2003-2005 ISB02 window, and, was getting a low fuel pressure diagnostic, I
told him that whatever was going on with the rig, replace or bypass the
strainer, and since he was web enabled, I gave him the link to the strainer
specs. He called me from the road Jan 2 saying he felt like the rig was back to
it's old self again, and the strainer was definitely clogged. He made it to
Naples on the Third , and will check on replacing the Racor with a Fleetguard
FF105. Breakdowns on Holidays are tough.

Hope this information helps.
Every day is a gift. If you have not had a bad Day,You will never know when your having a good one.




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