[brianmerc]

This is a 2 part problem, please read both parts. Any advice or input is highly appreciated. THANKS!!PART 1: My 1976 Mercury 1150, 115hp engine fires right up from a cold start after priming the engine with the priming bulb. About 20 seconds after starting, the engine slowly begins to die as if not enough fuel is getting to the engine. I checked the 3 carburetors and nothing was plugged up and everything in there seems fine. Could it be that the fuel pump isn't working??After the engine dies it won't start up again until I prime the engine again using the priming bulb. Same thing, it dies about 20 seconds after it fires up. I try to keep the engine from dying by raising the throttle. It works for a little bit, but then the engine slowly dies at full throttle. Could it be an electrical problem? Sounds to me that the engine is starving for fuel. As if the fuel pump has gone bad and the engine dies because there is no fuel being pumped into the engine to keep it running. PART 2: Here's the latest update on my problem. Well I went outside tonight and replaced the priming bulb with a brand new one. The old one was kind of old and cracking. Anyways, from a cold start, I primed the engine and it fired up on the second try. About 20 - 30 seconds later it started to putter as if it was gonna die. I ran over to the priming bulb and sqeazed it 2 times, and all of a sudden the engine purked up and began to run good. So, I am pretty sure it's the fuel pump not pumping gasoline to the engine. Here's where things got interesting: After pumping the bulb to keep the engine from dying, I wait another 45 seconds or so until the engine sounds like it needs more gas. All of a sudden after I pump the bulb more, then engine sounds good, then all of a sudden without warning, the engine just stops. I mean, no puttering, just DEAD. So I go to fire it up again, then its just cranking and cranking. Finally I think to myself that the engine isn't gonna start, so I let go of the key, and the engine fires up and scares the hell out of me. It was weird, the engine fired up as soon as I let go of the key. Hmmm... Sound weird to you?So anyways, I let the engine run for a bit, but then I noticed the engine didn't sound like it was gonna die. It was running on it's own now. I didnt have to sqeeze the bulb to keep it from dying. As if the fuel pump was working now. The engine normally idles at 1100 RPMs. Now, the engine was running on its own now but the idle would be at 1100 RPMs, then it would drop to about 800 RPMs. But it wasn't dying completely out. The RPMs were going from 800 to 1100, up and down. About 10 secs at 1100, then 10 secs back to 800. At that point I turned the engine off and let it sit for about 5 mintues while I gathered my thoughts. After about 5 mins, the engine fired right up with no priming. It was idling at 1100 RPMs and was staying there! The engine sounded great and it wasn't dying. It was as if there was no problem at all. SO FRUSTERATING!!So, I am going to wait til Thursday and I am going to try and fire it up again and see what happens. Could it be that the fuel pump isn't completely dead yet and decides to work occasionally?? Please give me some input on this, I highly appreciate it!!! I'm trying to trouble shoot as much as possible before I decide to go out and buy a new fuel pump. Does anyone know how much one sells for on a 1976 Mercury 1150?? Let me know if you have any ideas or input. THANKS!!

[chumbucket]

Try Boatfix.com

[Trent]

Those fuel pumps are re-buildable. Look at this link and get the 18- number and go to your local NAPA parts store and they can get the diaphram kit. Diaphram

[gbillingsly]

Have you replaced the fuel filter lately?

[mellowyellow]

disconnect the hose from the pump to the carb andput it in a bottle, crank it and see if it'spumping gas.pumps are easy to rebuild, just a diaphram andgasket.could also be stuck floats causing this. tappingon the side of bowl with but of screwdriver canunstick them sometimes.make sure tank is vented properly too.good luck,M.Y.

[brianmerc]

Thanks you guys for replying so quickly and helping me out!!I did check the filter screen on the fuel pump and it was clean. I did open up the 3 carburators and checked the filter screens to see if there was any junk that might be plugging it up. The Carbs were clean. One of the first things I did was tap on the bowl to see if one of the floats were stuck. They weren't. I opened up the carbs to see if they were dirty, but they were also clean. Tonight I am going to try and disconnect the hose from the fuel pump to the carb andput it in a bottle, crank it and see if it'spumping gas. I haven't thought of that, but it sounds like a good idea. As for the diaphram kits and rebuilding the fuel pump, I am not too familiar with that. How does the diaphram kit work? If the fuel pump is bad, will the diaphram & gasket kit fix my problem and begin pumping gas again? Let me know. You guys have been a huge help! THANKS AGAIN!!BRIAN

[RICKRICK1]

Brianmerc The fuel pump(s) is a real easy job. Normally 3 screws or small bolts. Fuel pump also has two check valves in it, check and make certain they are clean and operating.your manual should explain how. Also sounds like you may need a new switch as your sounds to be worn. If you can do carbs you can do the pump(s).Good luck

[brianmerc]

RickRick1, What switch are you talking about that could be worn out? Thanks for your reply, I appreciate it.Another question for anyone that can answer it:Isn't the check valve a needle valve? How does it work? I'm not too familiar with the check valve in the fuel pump.Brian

[RICKRICK1]

I was suggesting changing you start switch at the control as you said it started when you let off on the switch.

[brianmerc]

Well my start swith only had that problem that one night. I am going to rebuild the fuel pump this weekend, and if I continue to have a problem with that switch, then I'm going to take it to a mechanic to fix. Thanks for your reply!!

[RICKRICK1]

Sounds like you are on the right track, didn't know if the switch was a one time problem or not. Helped a friend with his (same) problem at start switch, he would release the switch and either have a flooded motor or it started right up. He never knew which.

[mbb]

rebuild the fuel pump no mater what, its simple. Old diaphragms are attacked by todays gas. the material they are made from has been upgraded. Get a manual from your public library if you dont have one. Even if theres not one on the shelf, they probably have one in the reference section (non-circulating) that can be xeroxed.

[brianmerc]

I went this morning and bought the diaphram kit and a new valve kit. I am going to rebuild the fuel pump tomorrow. I will let you all know what happens. Cross your fingers!

[Bear]

antsiphon valve Check this 2) Dead or no fire until you release the key switch: I hope this helps.

[brianmerc]

Woo Hoo! After rebuilding the fuel pump this morning, I fired up the engine. It started up on the first attempt, which it hasn't been doing since I had this problem. So, it started up and ran PERFECTLY and didn't die out like it has been. So it looks like I needed to rebuild the fuel pump. I even put new check valves in it just to be sure, this way everything has new parts in it. The engine idles steadily at about 1100 RPMs again! I could not have been able to fix this if it weren't for all of you that gave me the input I needed. So, I want to say Thanks to you guys! If I ever have any other problems it's good to know that I can come here for help!

[brianmerc]