View Full Version : 1989 Johnson GT 150hp (OMC)

06-26-2010, 11:08 AM
Ok I rebuilt my carbs, changed ALL gas lines from carbs to tank, primer bulb, and fuel filter. When the boat gets up on plane I can run for about 30 seconds before it starts sputtering. I hit the choke and it clears up. I know that the choke puts gas strait to the carbs which would make me believe that itís a fuel pump issue (or lack of fuel getting to the carbs). Also a buddy pumped the bulb while on plane and kept it running (man it ran good). The pump is 2 years old (back when they were $200). Since they are $400 now. I want to be sure itís the fuel pump. I tested it Thursday, after I put new lines on it, and when I was priming my bulb, the bulb collapsed. That tells me that I may have a stopped up line on the tank side. Question is how do I check the line inside the tank and is there anything else I can check if that doesnít work, before I order a fuel pump?

06-26-2010, 11:18 AM
Try putting your fuel line directly into the fuel tank and see if the bulb still collapses also the check valve in the primer bulb may be sticking closed causing a fuerestriction. also you can buy a rebuild kit for your VRO if your has one.

06-26-2010, 11:34 AM
Ok i'm stupid when it comes to this. Are you considering the fuel pump a VRO or the fuel pump with the oil pump a VRO. If its with oil I took that off 2 years ago and the fuel pump doesn't have a oil pump on it anymore. bought it without. I cant find a rebuild kit for my pump. have been told by 3 different parts stores that the rebuild kit was discontinued.

06-26-2010, 04:57 PM
First thing to check is the tank vent. Easiest way is to pump the bulb until it collapses, then remove the fuel cap and see if the problem goes away. If so, plugged tank vent. If not, try what rlc said above. If that cures it, then it is most likely the pick-up in the tank, or the fuel line from the tank to the bulb.

06-26-2010, 07:05 PM
The primer bulb collapsed? = Fuel restriction.......

(Fuel Anti Siphon Valve)
(J. Reeves)

Many of the later OMC V/6 engines incorporate a fuel restriction warning via a vacuum device attached to the powerhead. If the engine overheats, or if you have a fuel restriction, the warning is the same.... a steady constant beep.

NOTE... Only the V/6 & V/8 engines have the above "Fuel Restriction Warning". The warning horn will not sound on the other models.

The fact that a engine is not overheating, but the warning horn sounds off with a constant steady beep, and that the rpms drop drastically would indicate that the engine is starving for fuel due to a fuel restriction. Check the built in fuel tank where the rubber fuel line attaches to the tank fitting. That fitting is in all probability a "Anti Siphon" valve which is notorious for sticking in a semi closed position. It will be aluminum, about 2" long, and the insides of it will consist of a spring, a ball, and a ball seat. If this valve exists, remove it, knock out those inner components which will convert it to a straight through fitting, then re-install it. Hopefully that cures the problem.

The above procedure will cure a restriction problem with the anti siphon valve as stated. BUT, it may also allow fuel to drain backwards to the fuel tank when the engine is not running (siphoning backwards) due to the fact that the carburetors/fuel pump etc are higher than the fuel tank. This condition is not an absolute as the valves in the fuel primer bulb usually prevent this backwards siphoning problem. However.... if this does take place, the cure would be to install a new anti siphon valve.

06-27-2010, 10:39 AM
try running it on a separate 6 gallon portable tank to see if it works too

06-27-2010, 04:42 PM
Joe How do you get the dern thing out of the tank. I have loosened the nut. It appears to be threaded into the tank. I turn and nothing. It feels like there is a lock tab on the inside but there are no slits to slide the tabs through. Do I pry, continuing twisting or what?

06-29-2010, 03:56 PM
Your anti siphon valve should look like this use a deep socket and remove it. Here is a link for a replacement.

06-29-2010, 08:14 PM
Mine has an aluminum elbow threaded down in that fitting with the nut, one sides male other is female, it threads out along the fitting NTBRAN mentions. Looks like this one but aluminum. Hope that helps.

http://imageserv8.team-logic.com/store-logic/products/5/8709/tn_8805.jpg (http://www.marineengine.com/3/8-NPT-Male/Female-Brass-Elbow-033206-10-0/)