Greg W

Hello, Got her done finally. New lift pump installed behind the ECM, primed the system, fired her up and successful test drive done. Stumbling and lurching all gone. Thanks all for advice. Greg W

Backup camera or monitor leads?

No disrespect, but seems if faucets and low drains open then most of the water will gravity drain. Then by closing all faucets a little air will push remaining water out low point drains? I get a little more water out by finally running pump for 5 seconds or so. Gravity is your friend. Greg W

Folks ar Rev4 group told me Monaco lost all their records on microfiche some years ago due to a warehouse fire and that's why info and schematics are so hard to come by? Is this true? Greg W

I have no filters that I know of, haha but bet need done manually and might be an issue to fully draining system.

Sorry didnt mention you have to open upper kever to let air flow and replace the water.

When im on my last trip before winter, I drain fresh tank and open my low point drains in the water mngmnt cabinet and drive home with faucets all open. I also hold open toilet flusher so water drains back from it. I think movement of the coach helps insure good drainage. When I use air I first open all faucets and low point drains. After that I blow air in fill coupling with lever set to city water. Leave open low point drains , but close all faucets so the air pushes water thru the plumbing to the low points. Be gentle with the air pressure, but strikes me faucets must be closed or air will escape at first faucet and do nothing. Before finishing run water pump for 5 seconds or so to get water out of it snd out nearby drains. Only need to drain water heater using large outside plug. Catch most of it with bucket because will drain with good stream that clears heater shelf. Bucket needs to be 6 gallons or greater and yes last of it dribbles but thats life. Also plug should be anode tube to fight corrosion in heater, so get one if just plastic plug. Ive never used coolant and I live at 4000 feet and get hard freezes during the winter. Hope this helps. Greg W

Does Sparks rv repair do engine and driveline repair? Pass thru there some and good to know? Great idea to use jacks to check the sound!

Hey, hey. Found the beer can sized pump hiding behind the ecm cooling plates! Plumbing to it easy to overlook when tracing lines. Going to test for power to it and go from there . Move ecm out of the way and should be easy access. Busy life right now, so may be a bit, but will post up when resolved. Thanks all.

Thank you Bruce for most informative reply yet! Another mechanic friend coming to look tonight and your info will help a bunch. Didnt think had intank pump and even tho lift pump has failed she starts fine but lurches and stumbles driving! Amazing that high pressure pump has enough vacuum to start it. Getting close to solving this. Thanks to all who have chimed in. Thanks, cant hear pump run even if lying under coach so wondering if may have moved pump to tank between 02 and 04? Doing prime test only to see if any lift pump working at all. Filled filters when changed them and never lost prime which is nice.

Sparks/Reno has number of semi service centers that can fix what sounds like wheel bearing, but could be simple as brake backing plate rubbing against the wheel. They typically dont like mohomes but will work on them if nicely pushed for an appointment. Take a cab and go in person and like said above, sound knowledgeable and youll be better off. Understand they cant plug it in and while waiting and absolutley cant stay in it while in their yard for liability. Small shop maybe different, but most gonna say no. Winterize it and get a cheap room at a casino. Good luck and enjoy Reno.

Thanks, cant hear pump run even if lying under coach so wondering if may have moved pump to tank between 02 and 04? Doing prime test only to see if any lift pump working at all. Filled filters when changed them and never lost prime which is nice.

Thanks, what year is your coach Jim? Do you hear the pump when its running? Hearing by year of my coach, 2004 monaco may have switched to intank lift pump? Going to do priming test at secondary filter head and see if pumps fuel out with key on. Will tell me if lift pump working. Already have remote tank hooked in there and it ran great, so will be easy test. Separate hose at bubble primer, hold it in the tank and turn key on. Thanks for Irv2 link Ray. Greg W

Thanks Jim ,going to call cummins monday with new info.

Thanks Jim B for this valuable info. Do you think brother in law may know where his lift pump may be? Side of engine or tank? Inline fuse or in fuse block? Has he dealt with this same issue? Pushing fuel is easier than pulling so may have moved pump to tank. Monaco built their own chassis tho, so bet Cummins came in a box? Thanks Greg W

Thanks guys and RIP Bill D, Where is the lift pump found on pass side? Doesnt seem to be behind ecm cooling plates as have read? Great news that same as dodge in those years. Fuse box in battery box very vague! Ideas on fuse and relay locations? Thanks Ray and rip Bill D, glad to hear may not be dropping tank. Haha. Where is your lift pump found on pass side? Doesnt look like theres a pump behind the ECM cooling plates and cant hear anything running? Can only find pump # 3964407 pressure pump on pass. Thanks and sorry for redundant posts, but big fingers on little phone. Haha

Thanks Jim, if pump is in tank just hard to believe no mention in manual? Is it possible Monaco specd no lift pump because isb300 is smaller so the vacuum pressure from the pressure pump is sufficient? Tank is up against floor of coach and hard to see much but did find one can size bulkhead with wiring. Reading about complex sending unit made me think thats it, but better do more thorough check. Fuse panel in battery box vaguely labeled and will check some in line fuses too. Read here Bill D worked extensively with Monaco techs for years. Does he reply to posts or do I need to contact him directly? Thanks again. Greg W

Thanks Jim, on my 04 ISB 300 cummins it starts instantly and sounds fine even tho 0 fuel pressure at filter head. Does have 15 inches of vacuum pressure tho. How can engine even start if electric pump is down yet dont hear a sound when key on? Real head scratcher! In 04 could electric pump still be on drivers side of engine rather than intank.? Drivers side of engine has turbo, oil filter and alternator. Followed fuel lines along frame and see nothing? Today we tapped into the top of the fuel filter head and installed a fuel line to a boat fuel can to bypass the fuel system. Fired right up and no 25 15 fuel pressure code. Great test drive, good power and most importantly, no stumbling or lurching! So high pressure pump is good. There is an air leak or partial blockage in the fuel line somewhere that we bypassed, or an intank electric pump has failed and fuel system starves for fuel under a load even tho engine starts and idles? Really hope someone here can help wade thru this problem between the ISB 300 Cummins and an 04 Monaco. Did Monaco put a pump in tank but show nothing in manual ,and altho Cummins claims there's an electric lift pump that shuts off after 30 seconds we can't see or hear anything and no fuel pressure, yet runs!?!? How about it Bill D or others with good knowledge of Cummins and Monacos systems? Is there a secret electric pump in the tank? Thanks

Jim B, thanks for the reply, would you know the range of years for engine mounted pumps versus frame or intank lumps, or a source that might? Strange that my 400 page manual only dicusses the two fuel filters and the complex sending unit in the tank? No mention of any lift or transfer pump even tho doesnt appear to be one on the engine. If was on the engine would make sense that Cummins all the help I need. Thanks

Hello and great to find this site for some help with a head scratcher? Have a Cummins 25 15 fuel delivery pressure code and the symptom is engine stumbles or misses under load when driving, but not so much in neutral? Engine starts fine, idles and revs in neutral but will stumble badly going thru gears driving. My mechanics scan tool shows only about 1000 Bar pressure at 1500 rpms and he believes that is low. Pressure pump is rated to 1600 Bar pressure. Also when we checked for fuel pressure at top of filter head there was zero lbs yet when switched to vacuum pressure gauge it showed 15 inches at idle. Mechanic believes there is no engine mounted lift pump altho Cummins said based on my serial no. there is one that should run for 30 seconds and then shut off allowing fuel to pass thru. Problem is cant hear anything running with key on and there isnt any pump between water filter, ecm cooling plate, main filter and pressure pump. Based on my serial # Cummins shows lift pump # 3968187, but all we see on engine is pump # 3964407 and it is gear driven not electric. Engine serial # is 57165940. Very confusing based on what Cummins tells us. 3964407 pump is low on curbside of engine. Could it be the lift pump and pressure pump is hiding on driver side of engine or? Pic attached is of only pump found. Did Monaco put a transfer pump intank and say nothing about it in my manual? Or is vacuum pressure from pressure pump all it takes to run motor? We've changed out both filters and no leaks visible to allow air in. This saturday we are going to tap into filter head with fuel line and remote gas tank to see if stumbling solved. Any ideas greatly appreciated and if more info needed glad to add. Crazy thing is how engine starts instantly and even high idles fine yet shows no fuel pressure like would expect from lift pump? If rig has intank pump which fuse panel would it be powered from to check that before dropping tank? What might its fuse or relay be called? Sorry for huge first post, but as can see weve done lot of research troubleshooting this. So sad that all chassis diagrams lost in the Monaco fire Thanks for any help. Greg W