EFI onan

It's plug and play electronically. You will need to add a return line and the EFI pump plumbing wise. The units are identical dimensions so it will be a straight swap other than the return and the pump.

I was thinking in terms of buying the whole new EFI unit for the cases where a carb 5500 already exists. Just curious how plug and play the electronics into the toy hauler would be or any other things might not be thinking of. The switch to a high pressure pump and a return line is simple. Beyond this, just trying to determine how much of a drop in replacement it would be.

You're on the right track there tinner. You can not convert carb to EFI. It must be a full changeover.

I wasn't really thinking at the time I posted about converting a carbed gen to EFI, was thinking more of just purchasing an EFI gen. Had one company I talked to said they could after calling Onan, install a EFI gen instead of the carbed unit for a small fee. I just thought being an EFI model they would start quicker and easier. Won't mention the company in case there are laws that could possibly be stretched...just have to inquire when your looking at purchasing your RV and see if they can do it.

What needs to be done on the electronics side to switch from the carb to the EFI version? Seems like not much but wondering if its the same connection for the start switch inside the trailer or any other things that need to be changed?

dohler1 wrote:
Spoke to my local ONAN dealer about this exact issue. Here is what they advised:
needs the following in the Fuel tank:
--Supply return & purge lines for the EVAP EFI unit.
--Has to be rewired to just produce 120 volt as they are 120/240 volts

5.5 HGJAD-6759(diamond symbol)

if you have figured this out please let me know. I have the 5500 carbureted one now. I am always having issues with it. Want to go EFI on our new one.

You got some bad info there on a few fronts. The EFI comes in both 240v and 120v versions just like the carb unit. You'd only need the 120v model but could also use the 240v model as your rig divides the two circuits coming from the genset to the two phases in the circuit panel. No different than when you're on 50 amp service and have 240V entering your rig. As to the fuel lines, you already have the supply and EVAP line. You'd simply need a 3/8ths inch rubber return line. It's very easy to plumb that back into your fuel tank by using the filler neck adapter I linked below for $50. Then, the last thing you'd need is the EFI fuel pump which is different from the carb pump. It's really a straightforward and easy changeover. I just never got to it as my carb unit always works. I keep Stabil in the tank year round and never have an issue. Anyways, here's the tank filler neck adapter for the return line:

Filler neck tie in...

Spoke to my local ONAN dealer about this exact issue. Here is what they advised:
needs the following in the Fuel tank:
--Supply return & purge lines for the EVAP EFI unit.
--Has to be rewired to just produce 120 volt as they are 120/240 volts

5.5 HGJAD-6759(diamond symbol)

if you have figured this out please let me know. I have the 5500 carbureted one now. I am always having issues with it. Want to go EFI on our new one.

Good info Rodney.

I was told by Onan when I was considering converting to EFI that the EFI version still utilizes a EVAP line. I'm betting it's a big deal (IE: costs bucks) to get something CARB certified and they don't sell enough EFI units for it to be worth the expense yet. Just a guess though...

allcool wrote:

offtohavasu wrote:
Oddly enough, as it runs cleaner, it doesn't show CARB compliant on their website.

Interesting...

Although I have browsed CARB before on occasion, not up on its exact operations or guidelines.

Many manufactures find loopholes if the engine in question is more or less the same model/series as previous engines that have passed CARB. Not saying thats what happened, or that Onan is running with a non compliant genny, ijdk..?
More than likely if a carbureted engine that is more or less exactly the same, passed CARB, then the efi version should at least be as clean you would think, yes..?

jmo

That's common sense being applied. You know where the fits in CARBs regulations...nowhere. The EVAP generator is the one that is CARB compliant, and I'm wondering if the EFI version doesn't have an EVAP system, and that's why it is not. It sucks being in California.