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Carbfuel delivery help

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sebas54

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"Hi, I have 1987 4.3l gm merc.

"Hi, I have 1987 4.3l gm merc. I/O alpha 1

After installing a new fuel pump today I tried to start the engine. It wouldn't start. So, after letting the fuel pump run a couple of times I noticed that the fuel lines going to the carb looked swollen. I disconected the hose that is attached to the carb and there was a lot of pressure, enough that fuel was sort of spraying out. I tried to blow in the the inlet of the carb and it wouldn't allow any air into it. I removed the carb. and tried again. When I blow into it air will flow with alot of resistance but then it sounds like it clogged up and no more air flows. I blow from the top and there is little resistance and then all of a sudden the flow gets cut off.


Is the carb. supposed to be like this?


Is my carb clogged with something?

I checked the filter/screen/strainer from the inlet and it looked clean.


I replaced the fuel pump because the old was not working and when I removed the inline filter it was dirty with debris. I was trying to start the engine for a while, trouble shooting. Could I have caused the carb to get clogged?


Please help.


I can post pic's if it will help. I know that describing this my be vague but I tried my best.


Thanks."
 
in your carb is a float that i

in your carb is a float that is hooked to a needle/seat that when the fuel bowl on the carb is empty the float comes down and pulls the needle away from the seat and as fuel begins to fill the bowl the float raises and the needle closes. sounds to me like the needle is stuck shut
 
"I noticed that the fuel l

"I noticed that the fuel lines going to the carb looked swollen."

I have the exact same engine and there aren't any rubber fuel lines except from the tank to the pump. Someone has removed the steel fuel line required by the Coast Guard.

You are going to need to rebuild the carb due to the amount of crud inside it and the stuck float needle.
 
"Thanks for the info. The pum

"Thanks for the info. The pump that I installed is an electric pump. The hose comes from the water separator that is connected to the carb. There is a hose coming from the fuel tank which is connected a fuel filter, then the fuel pump, the the water separator, the the carb.

The pump that I installed is a carter 5-8.7 psi, 30gph.

Thanks"
 
"Hi, can can someone please gi

"Hi, can can someone please give me some input. I am sure that the hose are fuel hose and the fittings are all correct. I have ran the engine setup this way for 2 years without any problems. So, the carb. is supposed to work like this? When I removed the carb it was full of gas.


I also relaced the intake with a use one. Can this have anything to do with it?



Thank you."
 
"Have you taken the top off of

"Have you taken the top off of the carb and checked the float function and the needle fuel valve? If the bowl is full of crud it needs to be rebuilt! Blowing compressed air in the fuel inlet WILL knock the float setting off.

If the problem is not inside the carb the only thing that could be wrong would be the filter screen at the fuel inlet is in backwards.

We all feel that you should fabricate steel fuel lines from the pump to the carb or your boat is going to be one big firecracker one night. Using rubber fuel lines on the engine is crazy.
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"
 
"id like to know why that pump

"id like to know why that pump isint kicking off before it pressures enough to swell them rubber lines give this some thought is the pump defective
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if its standard3/8 fuel hose IMO that would take quite a bit of pressure to swell that. what you have there is a accident thats gonna happen"
 
I think I exaggerated with the

I think I exaggerated with the fuel line swelling. All the fuel lines are A1 fuel lines. I reinstalled everything and it seems to be working and the fuel line are not under a lot of pressure. I think the reason it's not starting is because of timing. I thought that the timing was set but probably lost it on the install. That is my next step in trying to start the engine. If that does not work I will look back at the carb or have a pressure test for the intake manifold.

Thank you all for all the advise.
 
Sebas we wasnt trying to be ha

Sebas we wasnt trying to be harsh with you at all but the info you gave us kinda scared us and we were trying to save you a big mess. come back anytime you need advice

steve
 
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