Onan Microlite 2500 Lp Service Manual

Posted : admin | On 17-08-2021

Onan HDCAA, HDCAB, HDCAC, HDCAD Generator Set (Spec A-D) Service Repair Manual. Onan HDKCA, HDKCB, HDKCC, HDKCD, HDKCG (RV) Generator Set (Spec A-E) Service Repair Manual. Onan RDJE, RDJEA Diesel Engines Service Repair Manual. Onan MDJA, MDJB, MDJC, MDJE, MDJF Marine Diesel Genset Engines Service Repair Manual. Onan MDJA, MDJB, MDJC Series. Manual The following safety styles and symbols found throughout this manual indicate potentially hazardous conditions to the operator, service personnel, or equipment. DANGER Indicates a hazardous situation that, if not avoided, will result in death or serious injury.

OnanIn my search to quiet down the Onan 2500 Microlite propane generator, I decided to install an Onan Resonator (Part# 155-2449) which was recommended by couple of RV.net members.

Onan Microlite 2500 Lp Service Manual 1

To start, first determine the placement of the resonator. You could either install it at the end of the generator exhaust pipe or somewhere in the middle section of the pipe. If you decide to install it towards the end of the exhaust, you may need a bigger u-bolt pipe clamp to accommodate the bigger resonator body. For cleaner/ stock look I opted for the later.
I removed the generator exhaust pipe by unbolting it from the internal muffler flange, then removing the 2-rubber hangers that holds the exhaust pipe. The exhaust is not a simple straight pipe rather it has 2 opposing 135 or so degree bend towards both ends.
Using a marker, I made a straight line along the middle section of the exhaust where the resonator will be installed, doing this made sure that the geometry and shape of the exhaust will remain same after installation of the resonator. Same straight line was made along the resonator body, this line should be in-line with the line made on the exhaust pipe once installed.Generator

Onan Microlite 2500 Lp Service Manual User

Using a metal cut-off saw, I

Onan Microlite 2500 Lp Service Manual Instructions

cut out about 10-inches long (double check resonator length, from collar to collar) section of generator exhaust pipe. I fitted the resonator, made sure it was properly aligned and then held it in place using tube clamps on each end. I then took the whole exhaust pipe assembly to a local welding shop and have the Onan resonator welded in place. The welding cost $10 and took less than 5 mins. I then painted the whole exhaust with heat resistant paint, or you can just paint the welds to keep them from rusting. If welding is not an option, a U-bolt clamp like this (U-Bolt Exhaust Clamp) maybe used to connect the resonator into the exhaust pipe.


Generator exhaust (with resonator installed) painted with heat resistant paint
I also fabricated a new exhaust pipe hanger, the hanger that came with it was made from hard rubber. When generator is running, exhaust vibrations is being transferred to the RT's body through the old hanger. I purchased an Exhaust Rubber Mount from local auto parts store. The rubber was really designed for automotive exhaust, so it was kinda thick. Using a hack saw, and periodically spraying it with WD-40 for lubrication, I spliced the rubber exhaust mount in half. The metal brackets were fabricated from a metal sheet. See pictures below.
Click on pictures to enlarge.

Onan microlite 2500 lp service manual instructions
New metal brackets

Side by side comparison of the new and old hanger. Disregard the new hanger upper bracket placement, I ended up mounting the brackets (upper & lower) on the same side of the rubber. I kept the old one as a spare.

From another angle. The resonator really makes a difference, I highly recommend installing one. The new hanger is a lot better than the stock one.
I found a YouTube video testing an onan resonator, you be the judge.

Model FA26120H (Spec H), S/N A000050942. It was made around the year 2000 and has 63 hours on it. It is installed in a truck camper.

Onan Microlite 2500 Lp Service Manual Download

Once started, it runs good and handles loads fine (A/C, microwave, etc.). The starting problem has been getting progressively worse. It only used to give me problems when it was cold. Now it is hard to start when it is warm out whether or not it has been running. Some other observations and things I have checked:
  • The air filter is clean.
  • It has a good spark when cranking. The spark plug looked clean but I replaced the spark plug anyway.
  • The primer solenoid does not pull in by itself when cranking. I have to give it a little push and then it will stay in by itself. However, if the engine fires it usually pulls itself in whether or not the engine starts. It goes back out once the engine starts or I let off the start button. If adjust the red dial on the plunger to 1 1/2 turns out per the service manual engine won't start (hot or cold) if it pulls in. The engine will fire, the plunger will pull in, and the engine stops firing. Sometimes the engine will start if I manually keep the plunger from pulling in at this setting. I need to have the red dial set way out (~ 5 turns) for the engine to be able to start when the plunger is pulled in. The engine will not (or rarely) start without the plunger pulled in.
  • The pressure balance hose is 24' long and does not appear to be blocked or have leaks. I can't disconnect it from the regulator due to access but I can disconnect it from the carburetor. If I lightly blow through or suck on the hose (be kind and hold the jokes) it freely passes air through the regulator. If I increase the pressure in either direction it checks off although it does leak slightly in either direction. If I disconnect or pinch off the hose while the engine is running it will run rough and die. However, if I pinch the hose while the engine is cranking it will often start. The engine will initially run rough until I release the pinch (unless it dies first), continues to run rough for a bit, then smooths out while surging, eventually settling out. This is one of the tricks I use to get it started.
  • The engine usually runs rough for the first second or so after starting and sometimes surges for a several seconds before settling down. I need to continue holding down the start button for a second or so after the engine has started or it will die if it is running rough.
  • Sometimes the starter solenoid chatters like I have a dead battery or bad connection even though the batteries are fully charged. I have not been able to find any bad connections anywhere between the camper and generator. I may have to repeat pressing the start button a few times to clear this and then it will crank fine. I don't know if this is related to the hard starting problem but thought I would mention it.
  • The propane bottles are full and all of the propane appliances in the camper work fine.

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Any help or suggestions would be greatly appreciated.
Thanks

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Sterling
---------- Post added at 11:56 AM ---------- Previous post was at 11:40 AM ----------

Onan Microlite 2500 Lp Service Manual Pdf

Also, if a moderator could correct my misspelling of Microlite it would be appreciated.