Chugging and hiccuping

[D Lindy]

Are the temps still down around 0? Did you let the motor set at and idle for about 15-20 minutes before taking off? Could still be a fuel gel issue if temps were 0.

[camping fam]

Thanks for the responses.

as for the air in the tank I don't think that is the issue as I have a breather tube on top of my tank and when I was under the Moho today I blew into it and could easily do so with an easy smell of fuel when I smelled the tube.

now this is what I have figured out with playing with it today here at the house. when I open the small petcock valve on the bottom of my fuel water separator I get air out then fuel, if I turn the key on as though I was getting ready to start it so this is what happens.
1 lift pump turns on and runs for almost a minute it seems louder/noisier than normal
2 if I leave the key on in this position after the pump turns off I then open the petcock and swoosh of air then fuel comes out but the pump does not turn back on simply stays off and the fuel is no where the capacity of the filter

Now I would think the pump would turn on and continue to pump fuel through the filter with the switch on and with the pump making a horrible racket (not normal sounds) I am thinking it is the lifter pump.

With this entire deal I had no issues before I took my Motorhome in for a simple oil and filter change and fuel filter change which Piedmont Fleet Services told me they would replace "two fuel filters" when I picked up the Moho they said the in rail fuel filter was a "inline air filter" I ended up using my extra Fleetguard filter and had to go to another shop and get the racor inline filter so basically I paid for these filters twice. After talking with several of my camping friends I have found out that the shop does not have a good reputation so do I call the shop and say hey what the heck did you do to my RV or should I just have it fixed and have our attorney send them the repair bill or just fix it and forget it?

[ladagobago]

Originally Posted by camping fam

Thanks for the responses.

as for the air in the tank I don't think that is the issue as I have a breather tube on top of my tank and when I was under the Moho today I blew into it and could easily do so with an easy smell of fuel when I smelled the tube.

"OK that is Good"

now this is what I have figured out with playing with it today here at the house. when I open the small petcock valve on the bottom of my fuel water separator I get air out then fuel,
"when you open this valve, you are opening the fuel transfer line before the lift pump.


if I turn the key on as though I was getting ready to start it so this is what happens.
1 lift pump turns on and runs for almost a minute it seems louder/noisier than normal
"running the pump now with the drain open you are pulling in air"

2 if I leave the key on in this position after the pump turns off I then open the petcock and swoosh of air then fuel comes out but the pump does not turn back on simply stays off

"the pump may stay on for only a few second and stops when it makes pressure to the injector pump of about 10-15 lbs.'

and the fuel is no where the capacity of the filter

Now I would think the pump would turn on and continue to pump fuel through the filter with the switch on and with the pump making a horrible racket (not normal sounds) I am thinking it is the lifter pump.

"I am not certain what engine you have but it sounds suspect"

.

On my MH the water sep filter is inline with the fuel supply from the tank and the lift pump pulls fuel through the filter so make sure all your connections are good and the drain valve is fully closed there is no pressure in the water sep filter assembly.

[camping fam]

Does the 2005-2006 cummins 300isb use the vp44 injector pump?

[1985 Bounder]

Also be sure that a genuine Racor filter was used. There are some replacement filters that do not have accurate fit that the Racor does and could be causing an aireation problem.

[camping fam]

Definitely a racor filter.

I think it may be the lift pump going out it seems noisy and could be an intermittent issue.

[camping fam]

okay so I have been busy with work (self employed) and have not even had a chance to work on the Moho but does anybody know how to check the fuel pressure so I know if it is the lift pump or not?

[camping fam]

So today I spent a little time and money trying to trace down the issue and trying to narrow down the fix to this problem.

1 Fuel pressure at idle is 8psi

2 my fuel system works in this order (tank, fuel line, inline racor filter/rock catcher, lift pump, spin on water/fuel separator, injection pump)

3 if air is getting in the fuel water separator it is probably from the lift pump acting up or failing under a load causing the injector pump to suck and this causing air in the fuel water separator.

From here unless I come up with another answer I am going to either put a lift pump on it which is $200 from cummins or I will have to take it in to have them look at it.

If anybody knows of anything else to try please let me know.

Thanks again to everyone for the help!

[charles tuit]

At approximately 80,000 miles my lift pump started to fail and eventually caused the injector pump to start acting up. $3,000 later and 100,000 more miles all is doing well. Just replaced the lift pump last month as a preventive maintenance measure as according to Freightliner in Tolleson, AZ 2 improved lift pump versions have been made since the one that was replaced at 80,000.

[jroethke]

We had a simular condition where the engine would run good at idle and good at full throttle but at mid range it would hiccup. Turned out to be the injector pump was going bad. Replaced it and the problem was gone!

[Randy125]

Do you know if the air noise you heard was air rushing into or out of fuel/water separator?

[camping fam]

The air was coming out of the petcock on the bottom and 8psi on the outlet side of the filter

[camping fam]

Installed new lift pump and now we have 11-12 psi with our newly installed fuel pressure gauge. Is this the correct amount of psi???