1150 won't stay on plane

[oldglass]

I'm new here and am having trouble with my old engine. It's a '77 (I think) 1150 merc. Ran perfect sunday, took it out tonight and starts great same as always, idles good, but when you go to full throttle it pulls the boat up on plane then dies. It seems like it runs out of gas the tank is half full. It starts right back up after it sits for a few seconds. I thought my filter was plugged so I removed it, still same problem. With the engine at idle I can feel the fuel line pulsing I assume it is normal for the fuel pump to pulse the suction line, I never checked before. The primer bulb didn't go soft, Is this normal? I never checked that before either. Any Ideas would help. Thanks

 

[Chris1956]

Re: 1150 won't stay on plane

oldglass, It is hard to diagnose your issue from the description. Do you think you are actually getting fuel to the carbs? Have someone pump the bulb while you try to run on plane. If the bulb is hard and the motor still dies, you may have a fuel restriction further down the fuel circuit.<br /><br />The carbs themselves have screens on them, which could be partially clogged. The backdrag carbs have a screen under the brass fuel inlet fittings on the carb bowl cover. The "normal" carbs have cylinder-shaped screens under the dome mounted on the carb bowl.

 

[Clams Canino]

Re: 1150 won't stay on plane

1977 is way too late for the carbs to have the big screens. The screens were gone by 1973/1974<br /><br />Some of the later ones may have had screens under the inlet fittings, but I've only found them in the fuel-pump inlet.<br /><br />Also make sure the bayonette fitting has a tight seal.<br /><br />-W

 

[oldglass]

Re: 1150 won't stay on plane

Thanks to you guys who replied. I have found and fixed the problem. It turns out that the primer bulb itself was the culprit. The check valve inside the bulb had come loose and were blocking the line. Replaced it and ran boat today without an issue. Thanks a bunch.

 

[Chris1956]

Re: 1150 won't stay on plane

Clams, Just so you know, my '77 1500 with backdrag carbs, has screens under the brass elbows and tee that feed the three carbs! They clogged up on me once, or I never would have found them!

 

[Clams Canino]

Re: 1150 won't stay on plane

Hmmmmm<br /><br />I'll have to pull a couple more off. Very strange place to hide them.<br /><br />-W