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Question about fuel pump

D

dhyams

Regular Contributor
"If a fuel pump is applied 12V

"If a fuel pump is applied 12V directly, what might cause it not to pump?

The only thing I can think of is that it must have a pressure sensor to tell it to stop pumping if the carb is full (i.e., the needle valve is shut because the float is at the top of the bowl).

I ask because I'm applying 12V directly to the pump via a pushbutton switch at the console, and sometimes it doesn't come on. There have been times that I pushed the button once, and it didn't work (at a cold start). I waited a few seconds, pushed it again, didn't work. Waited again a few seconds, pushed it, and it did work (filled up the carb with fresh gas)."
 
"All the electric pumps I have

"All the electric pumps I have worked with on boats and vehicles do indeed have a pressure cuttoff so they do not run when not needed.
I speculate that if a boat is free to roll about in the water, the float could open and close the valve whenever the fuel runs to one side or other within the bowl."
 
"[b]"If a fuel pump is app

""If a fuel pump is applied 12V directly, what might cause it not to pump?"

Ayuh,....

Bad Wiring, or an Internal Problem....

It Should run whenever power is applied...."
 
"David: Thanks....and as far

"David: Thanks....and as far as the float/valve, I'm doing this in my driveway, so there's no rolling around.

Bondo: I've verified at the fuel pump harness that I'm getting 12V every time I push the fuel-pump-start button. I supposed it could still be the wiring (in that I have to move the wire+harness a little bit to hook up a voltmeter to it) or maybe a problem with the electrical connection itself at the fuel pump. I'm going to pull it tonight and see what I see.

So I'm gathering that there's no way to service an electric fuel pump? Just replace it? I'm trying to make that I don't replace an expensive component that is perfectly good."
 
"Ah, and I forgot to mention t

"Ah, and I forgot to mention that I have no water separating fuel filter....the fuel line goes directly from the fuel tank to the pump. I don't know if that would affect the fuel pump performance or not, but I thought I would mention it.

It looks like a previous owner removed the water-sep fuel filter."
 
Daniel;
IMO you would be well

Daniel;
IMO you would be well advised to re-install the water separating filter. They are usually installed by the OEM for a good reason.

Rod
 
"Will do Rod; I was planning o

"Will do Rod; I was planning on reinstalling, and I might do it sooner rather than later (I was planning on waiting until end-of-season). Is it possible that the absence of the filter is causing problems? I'm just flailing about here, but could the pump be relying on the filter to hold a bit of fuel for it?

I know for a fact that there is never any fuel pressure in the steel fuel line that connects my fuel pump and the carb, after the boat has been sitting for a while (say a day). I'm beginning to suspect that perhaps there's a jammed-open check valve in the fuel pump itself. I don't know if the fuel pump is at all servicable, but I'm going to pull it tonight and try to take it apart."
 
"Daniel;
No, a filter will no

"Daniel;
No, a filter will not affect the pump operation, it just filters the gas. The fact that your gas has not been filtered may have a bearing on your problems.


The pump should supply the carb with a steady 4-6 psig of pressure when it is powered up, at all load conditions.

Rod"
 
"OK, pulled the fuel pump and

"OK, pulled the fuel pump and messed around with it a little. Couldn't get inside of it because it's sealed. Before pulling it, I verified again that, when power was directly applied, it just clicked sometimes (like the little turbine inside was trying to get going but it couldn't), and it ran sometimes. I guess it's time for replacement, unless anyone has anything else to add!

The model number is strange (122 3005A), and that's the only thing stamped on it. It looks just like the Sierra electric pump offered on this site though...

214530.jpg
The fuel pump."">

214531.jpg
A little gunk at the inlet screen
 
Daniel;
That looks right as i

Daniel;
That looks right as it references the carbed 4.3.

That should work for you and the price is right.

Rod
 
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