3.0 liter boggs

[lwb007]

hello all, i have a 1984 3.0 liter {gm} omc when i first put in water it runs great after a short time on the water it starts running rough spitting though the carb.had the carb rebuilt last year didn't help.it's really bad under a load/runs fine on the hose any ideas

 

[Bondo]

Re: 3.0 liter boggs

Ayuh,... It's Starving for Fuel,... You've got to figure out Why.....

Fuel Filters,...
Fuel Pump,...
Fuel Lines,...
Fuel Tank,...
Fuel Tank Vent,...
Possibly a Junk Carb, but I doubt that....But Maybe.....

 

[lwb007]

Re: 3.0 liter boggs

can't understand why it only boggs sometimes and other times it doesn't? it seems like the longer you stay on the water the worse it gets..

 

[Bondo]

Re: 3.0 liter boggs

it seems like the longer you stay on the water the worse it gets..

Ayuh,... 'cause it's burning More Gas....

 

[mylesm260]

Re: 3.0 liter boggs

First thing you should do is benchmark your fuel delivery to your carb.

#1. Grab a fire extinguisher and have it close by.
#2. Grab an empty jerry can.
#3. Disconnect the fuel line from the carb, and put it in the jerry can.

Then grab a stop watch, turn on your ignition, and time how long it takes to pump one gallon. Come back here, and post your findings.

If the number is too high (meaning it takes too long for 1 gallon to get pumped) than you may have a problem with your tank, pump, lines or filter.

If the number is good enough, than it may be carb tuning or something else.

It's a great test to find out which half of the system is at fault. And remember to be careful while dealing with fuel in such a way. Make sure the cover is off your boat, and everything is well ventilated, and there are no open sparks/flames.

 

[gdombroski]

Re: 3.0 liter boggs

Why not just replace the anti-siphon value? When they get gummed up will cause that.

 

[Bondo]

Re: 3.0 liter boggs

Why not just replace the anti-siphon value? When they get gummed up will cause that.

Ayuh,.... Why replace Anything ? til you know what's Wrong,..??

 

[mylesm260]

Re: 3.0 liter boggs

Exactly, Diagnose the problem first, then replace parts as needed.

Replacing random things on a huntch until the problem goes away is domestic car dealership mentality.

For example, What if his needle and seat is gummed up with crappy fuel he left in over the winter, or some foreign object that found it's way through the fuel filter?

If his pump can pump a gallon into a jerry can in a reasonable amount of time (30 seconds - 3 minutes, something like that) than we know the pump/tank/filter are probably okay.

If it takes a long time (5-10 minutes or longer ?) to get a gallon, than we know we've narrowed down the problem substantially.

 

[lwb007]

Re: 3.0 liter boggs

This a mechanical pump not en electric it's a 1984 model..

 

[mylesm260]

Re: 3.0 liter boggs

I see.


Well, I'm only 28, and have very very limited experience with mechanical fuel pumps. I'm assuming it's driven off your cam shaft.

I once bought a 1974 datsun 260z that had one, but I pulled the engine out the day after I bought it. =)

Ask the boating gods in here (don, bond-o, etc), how they would test it.

Off the top of my head, you could either

A) disconnect the line from your carb, remove your pump, pump it by hand, and ask the guys in here what you should expect for a reasonable amount of flow. (by hand I have no idea)

B) If you feel you can do it in a safe way, Put your boat on the muffs, heat up the engine, shut down the engine, disconnect the fuel line from the carb and put it in a jerry can, have someone else start the boat up (it will run with the fuel in the float at idle for quite a while), and while it's running, observe the flow of fuel into the jerry can.