Marine Carb bypass?

[vstol]

Hello all,

I noticed today while looking into some other problem that there is fuel coming / being pushed from my fuel pump straight to a fitting on my flame arrestor. This is on a 1992 431A Volvo w/ 4 BBL Rodchester. I pulled the line and held finger over line from fuel pump and noticed little change in engine RPM at idle.

What's the deal with that and should it be doing it?

 

[tommays]

Re: Marine Carb bypass?

That is a saftey line YOUR fuel pump has failed and should be changed before useing the boat at ALL

Tommays

 

[Don S]

Re: Marine Carb bypass?

It's only purpose is to put the fuel into the carb instead of the bilge. The only reason it would have fuel in it is if the fuel pump is bad. The fuel pump itself pumps the fuel into that hose.

 

[Don S]

Re: Marine Carb bypass?

What tommays said..........

THAT my friend is what is causing your rough idle. It's getting too much gas and running rich. Just like having the choke closed.
Amazing how having all the information can make troubleshooting a problem so easy.

http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=24;gtid=1147100

 

[vstol]

Re: Marine Carb bypass?

I suppose what i mean is what kind of a safety line, is it meant to suck fuel away, allow fuel to bypass, or some other purpose

 

[vstol]

Re: Marine Carb bypass?



What is the purpose of that line, is it there to indicate a failure or does it serve some other purpose usually?

 

[vstol]

Re: Marine Carb bypass?

Got it, so the pump has failed internally, some is now going though the line up through the flame arrester and the rest is still going up through normal pipe and tubes to front of carb.

Looks like this is going to cost about 100 bucks, not to bad for a boat part.

 

[vstol]

Re: Marine Carb bypass?

Off course I can not see a part number anywere on the thing, I tried stemtostern with engine serial number (868393 yr1992) got the stadard will email with info, dont have part number so cant use iboats, any other websites with 1992 and later vovlo stuff?

 

[Don S]

Re: Marine Carb bypass?

First of all, that 868393 number is not your serial number. The SN is 10 numbers long.
Second, the 431A only had one pump number, it's 855297. So you can cross reference to that number.

 

[vstol]

Re: Marine Carb bypass?

Thanks for all the help i am glad you put the two together before I was 10 miles off the coast of NC.

The experts on this forum are a lifesafer for the novice mech and boater such as myself

 

[lilmandavis]

Re: Marine Carb bypass?

make sure your fire ext. isnt all rusty!

 

[Don S]

Re: Marine Carb bypass?

make sure your fire ext. isnt all rusty!

WHY? ? ? ? ? ?

The tube in question was doing it's job. The gas was going into the carb and causing the engine to run bad, and not go all over the engine compartment.
The problem would have been with an automotive carb that drained out of a hole in the pump and dumped the gas in the bilge. Of course, if that caught a spark it would have blown the fire extinguisher overboard.

 

[vstol]

Re: Marine Carb bypass?

You know it is funny how we like to (maybe just me) put things off while they are still working, even if they are not working right. My boat has been doing this for at least the last 4 times it has been out. A couple of those times have been 5 to 10 miles out to sea to include 2 days ago catching some spanish mackrel. Not sure how long it will keep running with the bad fuel pump, but it wont be back on the water till I get a new one.

Thanks again for the help

 

[vstol]

Re: Marine Carb bypass?

I think I will look around and see if there is a thread out there that explaines all the differences between auto and marine parts, like the fuel pump, I had no idea what that extra line was for.

 

[lilmandavis]

Re: Marine Carb bypass?

i was talking about a fire extinguisher not arrester. its amazing how many people in saltwater have rusted out fire putter outters that are a bomb in themselves just waiting to blow out the side of them.