fuel pump

Joined
Mar 4, 2014
Messages
6
Hello new to forum have to replace mechanical fuel pump in a 84 four wins 170 candia with a 140hp mercruiser.
fuel pump is a carter low volume up to 6.5 psi. would like to replace with an electric fuel pump. Also would not like to spend 200.00 for a mechanical fuel pump. what is a good electric fuel pump one boat shop told me to use a mr. gasket fuel pump? what do you guys think?
 

JustJason

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Joined
Aug 27, 2007
Messages
5,319
Re: fuel pump

Just keep the mechanical. If you go electric you have to rig up an oil pressure switch to make it work right. And an oil pressure switch + relay to make it work reliably But on top of that, the mechanical pump is much more reliable than the electric fuel pump is anyways.

And if you don't mind making up a new steel line, you can use the newer style fuel pump, which is only 150 bucks.
 
Last edited:
Joined
Mar 4, 2014
Messages
6
Re: fuel pump

So I currently have a steel fuel line on the engine. Wouldn't performance and startup be better on electric pump.
 

JustJason

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5,319
Re: fuel pump

No it wouldn't change. Electric fuel pumps do not kick on until after the engine is already started. Aside from that, the fuel pump does not have much to do with starting as long as the carbs fuel bowl has fuel in it. If it doesn't, it's only another 5 or 6 seconds of cranking time.
 
Joined
Mar 4, 2014
Messages
6
Re: fuel pump

Okay thanks makes sense. So for carter fuel pumps I can just order online from iboats or is their somewhere else?

Oh and the reason for the pump is that I could only run my boat at 25 mph so my mechanic friend told me to replace fuel pump. boat use to do 35-40mph. got any ideas on that one.
 

81 Checkmate

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1,360
Re: fuel pump

Okay thanks makes sense. So for carter fuel pumps I can just order online from iboats or is their somewhere else?

Oh and the reason for the pump is that I could only run my boat at 25 mph so my mechanic friend told me to replace fuel pump. boat use to do 35-40mph. got any ideas on that one.

Now yer throwing parts at it with not realy knowing what the problem is......When was the last time you did a full tune - up?
 

JustJason

Vice Admiral
Joined
Aug 27, 2007
Messages
5,319
Re: fuel pump

Run a boat side fuel system test. It's in the stickies. It will test both your fuel pump and fuel supply to rule any of that in or out.
 
Joined
Mar 4, 2014
Messages
6
Re: fuel pump

Not since beginning of summer. Boat has been down since middle of summer. the day it went down very rough riding we knocked the carb. out of adjustment, the throttle rod out. Fixed all that the same day and we could never get off of plane. Rebuilt carb then she would plane out and only run 25mph. Got busy at work and was unable to use her. since then I have drained all old gas had a crushed filter in the fuel pump and cracked container around filter. Put new water separator filter plus adding another inline filter. my boat mechanic he is very wise and knows how I like to do it myself so he suggested new fuel pump. Also changed plugs, distributor, plugs. I will also say this when I bought boat it had sat for 2yrs without every touching the water. But if fired right up and ran awesome the first summer. the Second summer half way through now we are getting ready for crappie season so this is why. Any other pointers will be greatly appreciated. oh and fuel lines are clean.
 

old islander

Petty Officer 1st Class
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Jan 27, 2013
Messages
302
Re: fuel pump

Crushed filter may have let some junk into the carb. Could be an obstructed jet or needle and seat. How did the rough riding knock the carb out of adjustment? Your problem sounds more carb obstruction then fuel pump. When fuel pumps go...they go. Yours sounds more like a lack of fuel flow. I'm betting your problem will be found in your carb. Have you checked plugs for signs of lean condition? how about your float level? Did your fuel consumption change when your top speed changed? I'm putting my money on a carb issue. You can rebuild that carb for less then the cost of a new fuel pump. Another clue to your mystery...It sat for two years. In two years a lot of stuff can harden and build up in your fuel bowl. Think gas turning to varnish, and water separation if your running ethanol fuel. Now, when you start running new fuel through that carb it breaks down and breaks loose that junk that collected. I'm thinking carb issue all the way.
 
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achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: fuel pump

Do a 'standard' tune and then start looking for the problem. You might just find that the tune fixes it...

So, in this order.

1. Compression tests.
2. Check spark plugs, replace if they are more than a year/18 months old.
3. If points, replace, along with condenser and rotor. Check and adjust, if needed, points cam dwell angle.
4. Inspect distributor cap, rotor and leads, replace if necessary.
5. Check spark quality (needs to be a nice BLUE spark drawn over 1/2").
6. Set timing. Check timing advance is working correctly.
7. Check/change fuel filters and check that the fuel system is not sucking air.
8. Check fuel pump pressure.
9. Check for full opening of the carb. Also ensure choke is opening fully when the engine is warm.


Chris.....
 
Joined
Mar 4, 2014
Messages
6
Re: fuel pump

ok will do this week or next week thanks for all answers. A little cold down here, I replaced wires, plugs, distributor cap, rotor and leads because they were original haven't reset or checked timing yet but will do. Fuel filters are new and fuel pump is going to be replaced and lines will be replaced.. I will let ya'll know what I come up with.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: fuel pump

.... so my mechanic friend told me to replace fuel pump. .....

He's just guessing and spending YOUR money in the process. I'd need to see WAY more diagnostics done before coming to a conclusion about ANY specific part needing replacement... Loss of boat speed has about as many causes as there are boats, and fuel pump is a LONG way down the list!

Best advice at this point, do not listen to this 'mechanic'.... He's full of it.

Chris.....
 

old islander

Petty Officer 1st Class
Joined
Jan 27, 2013
Messages
302
Re: fuel pump

^^^ totally agree with Chris. Chris is the Chuck Norris of boat repair.
 

thumpar

Admiral
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Jun 21, 2007
Messages
6,138
Re: fuel pump

For the price of a fuel pump you could probably get it properly diagnosed by a shop. I highly doubt it is the pump.
 
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