Couple issues

[Mcboater669]

Ok so I just bought a 91 Reinell with a omc cobra 5.0, and I’m having a fuel boiling issue after about an hour and a half to two hours on the lake what would cause this? The back doghouse was removed for a flush bench so tons of room in the engine compartment now. Also the previous owner “rebuilt the carb” and I’m assuming played with the mixture and idle I am not familiar with tuning a carb on a gas motor industrial lpg I have done so I’m sure I can figure it out just don’t know what screws and knobs are what.

 

[dubs283]

Fuel boiling? Like it's hot and boiling? I immediately thought of vapor lock but other than fuel spilling out of carb and landing on a hot intake can't say I've seen fuel boil before

I would start with a carb rebuild. Would guess your carburetor is either two bbl rochester or holley. Both very simple carbs and quite easy to rebuild. Plenty of info online for parts/information regarding both

 

[Scott Danforth]

My first thought is the engine is running hot. With your new to you boat. Make sure you do all the maintenance the prior owner didn't do

Like the impeller service, annual drive service, u-joint inspection, alignment check, etc.

 

[Bondo]

Ok so I just bought a 91 Reinell with a omc cobra 5.0, and I’m having a fuel boiling issue after about an hour and a half to two hours on the lake what would cause this? The back doghouse was removed for a flush bench so tons of room in the engine compartment now. Also the previous owner “rebuilt the carb” and I’m assuming played with the mixture and idle I am not familiar with tuning a carb on a gas motor industrial lpg I have done so I’m sure I can figure it out just don’t know what screws and knobs are what.

Ayuh,..... Welcome Aboard,...... Just how did you come to that conclusion,..??

 

[Mcboater669]

Ayuh,..... Welcome Aboard,...... Just how did you come to that conclusion,..??

I have had this issue on a buddies car in the past. Im a HD mechanic by trade so not as familiar with smaller motors and carbs so most of my knowledge (which isn’t great is from watching roadkill, engine masters, stuff like that.

 

[Mcboater669]

My first thought is the engine is running hot. With your new to you boat. Make sure you do all the maintenance the prior owner didn't do

Like the impeller service, annual drive service, u-joint inspection, alignment check, etc.

Was all done with receipts when it got de winterized a month ago impeller, drive service oil change fuel filter, but buddy said no to a carb rebuild “because dads a mechanic”……..

 

[dubs283]

Still don't know what a fuel boiling issue is nor have you given any description of what you're experiencing with the motor.

Guessing it's running poorly, can you give us any more information?

 

[Mcboater669]

It will be running great 3500 rpm cruising then just lay over rpm drop to about 5-600 then kick back up, by that point iv already throttled back water temp doesn’t go above 170 stays between 150-160. Let it sit for about 5 mins and will run fine for another hour and a half to two hours, then same thing.

 

[dubs283]

First guess is something temporarily blocking the pick up tube in the tank. When you come off plane/throttle back the debris eventually comes off the tube and your back in business

What does fuel boiling issue mean?

 

[Mcboater669]

First guess is something temporarily blocking the pick up tube in the tank. When you come off plane/throttle back the debris eventually comes off the tube and your back in business

What does fuel boiling issue mean?

Your fuel gets too hot going into the carb and boils. But the debris idea actually makes sense too

 

[dubs283]

Your fuel gets too hot going into the carb and boils.

Would only expect fuel to be hot enough to boil in the case of an extreme overheat, or vapor lock on a hot, idling engine

At 3500 rpm the engine cooling system, if sound ought to be keeping the motor cool enough to run at optimum temp. The fuel in the delivery system won't be there long enough to heat soak enough to boil/vapor lock

 

[Mcboater669]

Would only expect fuel to be hot enough to boil in the case of an extreme overheat, or vapor lock on a hot, idling engine

At 3500 rpm the engine cooling system, if sound ought to be keeping the motor cool enough to run at optimum temp. The fuel in the delivery system won't be there long enough to heat soak enough to boil/vapor lock

The debris in the tank sounds more plausible now then well that sucks…… anyone k ow how to get the tank out seriously thinking it might be easier to just put in a fuel cell and be done lol

 

[dubs283]

Best access for inspection is to remove the fuel guage sender.

As far as tank removal i have no clue. Some boats you need to remove the floor/deck to access for removal

 

[Lou C]

Fuel boiling in the carb or fuel lines can happen but it is rare on boats. It is more common on older carbed vehicles due to higher cooling system set points of approx 40*F higher than a marine cooling system. I recall people putting a wood or phenolic spacer under the carb & insulating the fuel lines. Those things did work. As far as the boat with the 4.3 Quadrajet I have never experienced it.

 

[Mcboater669]

4.3? It’s a 302 ford with a Holley 2 barrel my apologies I didn’t put that in the original post

 

[Lou C]

No the 4.3 QJet is in my boat.
Holley carb has the fuel bowl up above the intake manifold not likely to have fuel boiling even in hot temps.
Years ago we had a 1970 Ford with a 302 & the Ford Autolite 2100 carb. This one did have fuel boiling & I insulated the fuel lines with heat tape.