OMC 165 carb problem I think

"I have a houseboat powered by

"I have a houseboat powered by a 1974 OMC 165, 2bll carb. I can only get the engine running at high rpm's. It will not idle. Even while at high rpm the engine will eventually die even if I pump the throttle. Is this most likely a carb problem? I also heard if the distributor is not advancing this can cause the same symptoms. Any help with be appreciated."

"the primary circuit will caus

"the primary circuit will cause that, yes it the mechanical advance isn't returning it can also cause that but I'm not sure you would get it started.

The mech advance is easy to check, with out removing any wires, take the dist cap off and see is you can rotate the Rotor Clockwise and see if it returns, if not than look further, maybe a return spring broke off.. dont use just any sping though, needs to match else the advance wont be right.

I recently bought a new sierra carb for my 165, while I could and before the price went up, last fall, there are some modifications Sierra/Mercruiser made that will hopefully help the efficiency. You may just need a good rebuild. A lot less than new, only problem would be if the throttle shaft is worn."

"Brian, thank you very much.

"Brian, thank you very much. I did check the distributor and it does return as its suppose to so that leaves the carb. I pulled it and dropped it at the carb shop for a complete rebuild. Thanks again for your help. It helped me narrow the problem."

"What Brand of Carb? My V6 has

"What Brand of Carb? My V6 has a one barrel Carter, and the check ball was sticking, due to glazing of old gas. This caused flooding at idle. I tore the entire carb apart, and it runs fine now.Oh yeah, a new needle and seat as well."

"Scott, my 250ci carb isn'

"Scott, my 250ci carb isn't much bigger than your 225ci carb."

"But you said it was a 2 barre

"But you said it was a 2 barrel. Mines a 1 Barrel, on the V6.I DO have a 2 Barrel Intake, but it uses little gas now, and goes like stink (really good).
A good investment is the Seloc Manual for OMC. I bought one, and it was the best money ever spent on my boat.. along with the useful info plucked from here....
All I need to do now, is monitor the plugs to make sure it's not too rich. Starting setting was 1&1/2 turns out."

"Well, I'M back to scratch

"Well, I'M back to scratching my head. The new carb (rochester) didnt solve the problem. I also put in a new fuel pump and the same problem remains. The engine dies as soon as the fuel in the bowl is used up. I pump the thottle a few times and it starts and dies again. Distributor seems ok. I'm not sure where to go from here."

"' The engine dies as soon

"' The engine dies as soon as the fuel in the bowl is used up.'

Yo me an indication that the pump for some reason does not work?
Hook a separate tank with primer bulb straight to the carb and see if that 'solves' the problem, using the bulb as pump.
Then hook it to the pump (if ok) and check the pump function eliminating the boat tank and line system. Work Your way back towards the tank, it might be an air leak/blockage somewhere."

"I agree with Morten, It seems

"I agree with Morten, It seems to be a gas problem and have to make sure that there is no restriction or air leak coming to the gas pump.If that's working than check right after the pump. If gas is coming take the gas filter from the carb. make sure that it is not blocked. Get some quick start spray and spray it in the carb and crank. Al along to me sounds like gas starvation. Good luck."

"[b]"I pump the thottle a

""I pump the thottle a few times and it starts"
If there's no fuel in the bowl, pumping the throttle probably wouldn't help. Are you sure the idle circuit is clear and adjusted correctly?"

"Ok so you say you had the car

"Ok so you say you had the carb rebuilt? Or is it a brand new one? Reason i ask is a carb rebuilt even by a expert has at best a 50/50 chance of ever giving good service. Was the rebuilt carb at the shop that rebuilt it, run on a motor? If not it's not a real carb rebuilt expert doing the work.

The fitting that enters the carb has a filter it clean? There is a filter in the fuel pump, it clean?

Ok you have a fuel / water separator on the boat? Replace the element. Now you know the system is clean, remove the hose from the fuel pump inlet and install a hose that runs to a external tank.

You ever check what psi the fuel pump is giving you? Should be between 4-6 psi no less no more.

Run the boat it fixed, runs good ? If yes then you know it's something with the onboard tank. Remove the fitting that enters the onboard tank, that the fuel hose connects to, it should be a anti-syphon valve. It has a ball in it that allows gas to flow one way, blow thru it, look thru it. It clogged up, dirty clean it or replace it if bad.

The fuel pickup tube should have come up out of the tank when you unscrewed the fitting, it should have a screen on the bottom it clean ?

Next check the vent it clean, blow are thru it, no spiders or animals living in it? If vent is clogged, running the motor will cause a vacuum condition in the tank and the pump can't pump fuel causing the carb to run dry.

Now you have a choice at this point, to pump the garbage and water off the bottom of the tank or not. If you want to, than stick a 3 or 4 foot hose connected to a cheap dc fuel pump that you can buy at any auto store, with a hose long enough to reach a clear plastick container, and pump the garbage and water off the bottom of the tank till you see clear fuel and then shut off pump,pull hose and close up tank.

Long post but the only way to get to the bottom of this problem is to make sure you have a clean system with a good carb."

"Chiefalen, the carb was rebui

"Chiefalen, the carb was rebuilt at a carburetor shop, pretty much all they do. I have checked all filters, fittings, etc. All appear to be clean and in working order. I checked the fuel for water using a substance (unknown name) that turns reddish/pink if water is present and it is clean. Still having the same issues.

I appreciate your assistance and everyone who has responded. I'm sure its something fairly simple but no luck narrowing it down yet."

what Morten said to do with a

what Morten said to do with a remote tank will probably lead you to what Chief said about the anti-siphon valve.

Have you checked the line comi

Have you checked the line coming out of the gas tank? if you can pull any gas out.

"Yes,I can pull gas from the t

"Yes,I can pull gas from the tank line. I think I am still going to try the remote tank and see what happens."

"Since the rebuild, are all th

"Since the rebuild, are all the symtoms the same as your initial post indicates? For instance, "I can only get the engine running at high rpm's. It will not idle." And, "Even while at high rpm the engine will eventually die even if I pump the throttle." Could be more than one problem here. Do you know for sure that the fuel bowl on the carb is running empty? Have you tried looking down into the carb while pumping the throttle 2-3 times to see if you can see fuel squirting in the throat. If you do theres fuel in the bowl, if not, you may have a restriction. If you suspect a restriction then trying an external tank as suggested earlier, could prove so."

"Thanks for the response. Yes

"Thanks for the response. Yes, there is fuel squirting. I am going to try the external tank.

Thanks again to everyone who responded."

"please dont tell anyone, I ha

"please dont tell anyone, I had an issue that I in advertantly put/left 2 washers on 2 studs of the carb causing a vacuum leak, there by requiring the carb to provide more fuel which it didn't but the engine did run, and ran better at high, then low. it would die at low rpms, just remembered.

Maybe there's a port on the carb base that should be plugged, if they used an automotive carb or base. Could also be a leak on the adapter between the carb and the manifold."

""I pump the thottle a few

""I pump the thottle a few times and it starts"
Means there's not enough fuel at start, in turn theres a possibility for a vacuum leak causing air to bypass the carb."