Caribou
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Re: Onan 3600lp turns propane regulator to red
Well I installed the unit in to the RV yesterday. Got everything hooked up, bolted down and wired in. Made sure the demand regulator opened properly by hitting the prime switch and blowing a little on the vent hose. Cranked and started right up......... and then promptly sent the RV propane regulator to red and shut down. I about cried. I went through the whole process in my head. It ran just fine in the garage, what had changed. Through process of elimination I determined it was the pigtail hose. NRALIFR nailed it again. I never suspected the pigtail hose because in theory that would only effect the propane flow from one tank, not both. If the pigtail was bad on one side the flow would be fine from the other side, but both sides produced the same results. I had a long pigtail made a couple years ago so I could bring a separate larger propane tank with me on long stays. I had the original pigtail that I used with my temporary set up in the garage. The original pigtail worked fine. So, I still believe the demand regulator was not working right because the generator did not run even with the good pigtail until I rebuilt the demand regulator. It was a combination of things, both pigtails and the demand regulator. I don't know how all that could have happened unless it was caused by the same event. 99% of the time I get my propane from a large supplier here in town. I don't use gas stations or U-haul or what ever. I don't think I got bad propane, and even if I did get one tank of bad propane, how would it effect the other side pigtail? I really don't understand how it could have all happened at the same time, but it did. Anyway, thought I would follow up with that news. Going down to the propane supply house today to replace those lines. Thanks for all the help!511Views0likes0CommentsRe: Onan 3600lp turns propane regulator to red
I agree, the demand regulator must be a finicky system because there was absolutely no indication mine was bad. The diaphragm had no holes, the valve seat seemed to close and open properly and the troubleshooting test per the service manual did not indicate any problems. Obviously the diaphragm wears out to some degree which makes sense since it is a flexible sheet of material and in my case is about 10 years old sitting in a very dry climate. I have the prime option on my unit also, but like yours all it does is open the electronic shut off valve and allow flow to the demand regulator. I suppose a simple prime would be to blow slightly in to the demand regulator vent tube while holding the prime button. That would open the demand regulator and allow flow to the carburetor. Thanks for the pat on the back, I feel pretty good about getting it fixed.510Views0likes0CommentsRe: Onan 3600lp turns propane regulator to red
I received the demand regulator rebuild kit yesterday. It contained more parts then I needed because it is used for several different versions of the 52N regulator, but it had the parts I needed. Basically I changed out the shut off seat, the shut off valve, the spring and the diaphragm. I put it all back together and she started right up and ran smooth. I can't really say what might have been wrong with the old regulator, but I imagine the diaphragm wears out and somehow either allows too much or too little fuel flow to the carburetor. I did not hook up any load to the system yet but once the generator started the circuit board seemed to take over and run the throttle plate normally. I'm going to get it installed back in the rv this weekend. The frustrating part of this was the complete lack of information on the troubleshooting. If I had gone by the Onan tech manual I would have replaced the circuit board before I suspected the demand regulator. I would have taken the whole brush assembly apart and performed other unnecessary tests. The tech manual clearly says the demand regulator is rarely the problem and all other troubleshooting steps should be performed before replacing the demand regulator, right. The test of the demand regulator only tells if it opens or not, it does not test for fuel flow. I found one thread on the web that documented this problem in another forum. The guy did all the tests I had done and he finally ordered a new demand regulator and then let the thread go stale and never said whether it worked or not. Any way, I'm glad it finally seems to have been fixed.510Views0likes0CommentsRe: Onan 3600lp turns propane regulator to red
Finally found a repair kit for a decent price http://www.centuryfuelproducts.com/parts/repair-kits/52b-rbk-repair-kit.html I believe this will work for my regulator. This is a repair kit for a regulator with a primer, which mine does not have, but I believe the main diaphragm is the same for either model. For $25 I will take the chance.511Views0likes0CommentsRe: Onan 3600lp turns propane regulator to red
I read a lot more over the weekend. Had to do the glow plugs on my diesel, so I didn't spend much time on the generator. I borrowed good compression gauge from a friend because mine is pretty old and beat up. The compression test with his gauge read 150 lbs, so I know the engine is good. I wish I could find a rebuild kit for this demand regulator. The test with the manometer between the demand regulator and the carburetor should measure a slightly negative pressure. This is due to the vacuum of the piston pulling the fuel in the the cylinder. I still haven't done that yet.511Views0likes0CommentsRe: Onan 3600lp turns propane regulator to red
I will have to do that test tonight. Didn't get to it last night. I removed the demand regulator and was prepared to just replace it but I took it apart and it is a very simple device. Now I can understand the test that I did to verify the demand regulator is opening properly. I am back to looking at what the output flow from the demand regulator is showing while the engine is cranking. I will try to do that in the next couple days and get back. I'm getting frustrated now because I really thought that was going to be the issue.511Views0likes0CommentsRe: Onan 3600lp turns propane regulator to red
nralifer, thanks for the link. The way my generator sits I doubt I could reach the regulator to prime it manually. Also I have the electronic solenoid shut off valve prior to the regulator that doesn't open up until the start switch is pushed so no fuel would get to the regulator anyway. I really appreciate all the help. I will let you all know how this winds up.236Views0likes0CommentsRe: Onan 3600lp turns propane regulator to red
I'm thinking of the demand regulator as the float and jet of a carburetor. The fuel pump may be putting 5 lbs of pressure in to the system but that is not going in to the manifold to deliver to the piston. The 11" is coming off the propane regulator and the demand regulator has to reduce that down and open the flow as required by vacuum. If the demand regulator allows too much flow when it opens its like flooding the fuel bowl of a carburetor.236Views0likes0CommentsRe: Onan 3600lp turns propane regulator to red
hmmm, Wizard, you confused me there, sorry. The manometer would show the inches of water column. If the demand regulator should reduce the pressure coming from the propane regulator then the water column should be greatly reduced coming out of the demand regulator. If the water column coming from the demand regulator is close to the 11" coming from the propane regulator then I have a problem. Am I thinking about that right?236Views0likes0Comments
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