gas spewing from hoses on valve covers

[cptgeorge]

I am working on a volvo 4.3 vortec with a holly 2bl carb. I have just put a rebuild kit in the carb and when running the motor gas spews from the hoses on the valve covers...lots of gas like a garden hose. the motor will not start unless fully throttled and then runs very rough, the gas does not spew out for about 10 sec and then just shoots out with out stopping. Im guessing that I have done somthing wrong when rebuilding the carb and the vacum is just pulling all of the gas thew unchecked, but what would cause this. If I forgot the gasket ring on the power valve would that allow this amount of fuel to pass threw. Any input will help, and thanks.

 

[superpop]

Re: gas spewing from hoses on valve covers

How much gas are we talking about and are you sure it is gas. Sounds like the floats are not set up right and gas is just dumping out of the bowls and down the intake but it should not be so much that it sprays out the vent hoses. If it is doing that then the next question is how is so much gas getting past the valves. did it run before you did the carb job? If it did then I would double check the carb for problems. You will also need to change the oil most likely because it is probably diluted with gas now. Be very careful with this one as you have a high boom factor going on with that much gas in the wrong places.

 

[Don S]

Re: gas spewing from hoses on valve covers

when running the motor gas spews from the hoses on the valve covers...

Are you talking liquid gasoline, or are you just seeing some smoke or steem coming from the valve covers?
In reallity, there is no way for gasoline to be coming out of the valve covers.

 

[cptgeorge]

Re: gas spewing from hoses on valve covers

we are talking about a lot of gas enough to measure in quarts definatly gas. the boat did not run before, it is a huricane boat bought at auction. the oil is now full of gas clear to the top of the dip stick. the boat has not run for more than a minute or two total with good clean oil to start. the gas is definatly comeing out of the valve cover vents and enough to flood the oil containing area and blow out quarts worth. I dont beleave that my fuel pump could pump that much gas that quickly and amazes me that much fuel could pass through the carb...but guessing that the vacume from the intake has to be pulling it through? thanks for the quick replies, hope this helps.

 

[legoman67]

Re: gas spewing from hoses on valve covers

Maybe a picture would help, is fuel pouring out through the flame arrestor aswell? how is it getting into the valve vents, are they not just hanging off the side of the flame arrestor?

 

[Don S]

Re: gas spewing from hoses on valve covers

I suggest you do not start that engine again. The fact that it hasn't exploded into a huge fireball is remarkable. You MUST get all the gas and oil out of the the engine before you ever introduce anything resembling a spark to the engine again.
For raw gasoline to be coming out of the valve cover vent hoses, the crankcase must be completely full of gasoline.
The fuel pump has to be your problem, vacuum would pull the fuel from the carb into the cylinders, and in that quantity would first flood the engine so it wouldn't riun, then hydrolock the engine, not fill the crankcase and blow out the vent hoses.

 

[chiefalen]

Re: gas spewing from hoses on valve covers

Is it in a well vented area away from the house and any other structures?

Take the key out, and put it in your pocket. Fumes are more dangerous then the actual gas itself.

Leave the motor cover off, and as Don posted drain the oil and gas and dispose of properly. Don't forget the oil filter. new one.

You will have to test the fuel pump 4-6 psi no more no less.

Careful around the motor real careful. A spark within 50 feet will ignite the fumes believe me, so don't touch anything with a wrench except to drain the crankcase.

Fill it back up with the correct oil, test the pump and then see if the float is still floating in the carb and the needle is seated properly.

You will need to change the oil after 10-15 minutes after you get it running.

Don't forget to get 2 filters, one for the change and then another for the next change.

 

[tinman565]

Re: gas spewing from hoses on valve covers

First of all, I'm not familiar with that engine..but..LETS GET BACK TO BASICS. I dont know if that motor has a mechanical fuel pump, or electric. Either way, there is no way for the fuel to get into that motor without going thru the carb first. Either pump has an inlet..and an outlet..thats it. Outlet is obviously going to the carb. Now, getting back to basics, that carb has a needle and seat configuration for the float. If that is not set up correctly, the bowl will overfill, and the excess fuel is suposed to exit the bowl thru the vent and into the venturis to be inhaled and burned by the running motor. I dont think we are getting the whole story here (did you replace or rebuild anything else on this motor ?..everything on and around the intake looks good ?). If you turned the motor over time after time after time trying to get it running or to fire, then I could see alot of fuel being introduced into the motor. Especially if you had the flame arrestor on, and couldnt see anything. Problem is..it should have hydrolocked, or at least had raw fuel coming outta the exhaust. I say change the oil (carefully), take the carb to a respected re-builder, and try getting the boat running again. Leave the flame arrestor off this time, and have someone watch the carb while you turn the motor over. Look for excessive fuel being dumped into the engine from ANYWHERE. I think you somehow flubbed the rebuild on the carb. Take it to someone who knows a thing or three about them, pay the man for his knowledge (its cheaper than a new boat, your garage, house, and life) and please...please be safe with that bomb.

 

[300sflyer]

Re: gas spewing from hoses on valve covers

If it's a mechanical fuel pump on the side of the block, could the gas not go straight into the crankcase if the pump was leaking internally?

 

[chiefalen]

Re: gas spewing from hoses on valve covers

Should go up the hose into the carb if it is a marine carb.

That pump should be tested and the carb set up again right.

 

[tinman565]

Re: gas spewing from hoses on valve covers

I dont believe so. If the diaphram was torn, or ripped, it wouldnt be able to "pump" fuel anywhere. I think they are designed not to pump fuel into the block if that were to happen. If that were the case, we would hear of alot more people with this problem. If he wanted to be sure..spend the extra money, and buy a new pump and install it. Would be worth the peace of mind just knowing you had a new pump on the motor. Either way, I hope he safely figures this out and lets us know what the problem was.

 

[a70eliminator]

Re: gas spewing from hoses on valve covers

the fuel pump has a fail safe (well maybe not safe) but in the event the fuel pump diaphragm ruptures cracks tears whatever the raw fuel should leak externally through the little weep hole in pump body, If the pump has catastrophic failure then i don't know maybe a that in conjunction with a failed anti-siphon valve in the tank could somehow fill your engine to the gills.

Whatever it is sounds like a potential explosion to me.

 

[Don S]

Re: gas spewing from hoses on valve covers

I thought I read he had a 3.0L which has a mechanical fuel pump.
Not sure what he has with the little information he gave about the 4.3 Vortec. I would guess electric, but who knows. A model, year, SN anything would help at this point.

 

[tinman565]

Re: gas spewing from hoses on valve covers

Ok...lets say it is electric...now the fuel has NO way to get into block without going thru the carb first. Like I said earlier..I think theres more to this story, and alot of info being left out. He had to have been turning it over for awhile to get the whole oil pan filled with fuel...and that would be ALOT of fuel. Did he change the oil before he did all this (after he bought the boat at auction) ? It was a hurricane boat right ? If he didnt change the oil first, how does he know the pan wasnt filled with oil, WATER, fuel to begin with ? With the pan being that full of whatever..it makes sense that the engine turning over is gonna cause pressure from the BOTTOM of the pistons, and try to blow that stuff outta the valve cover vents. I'll bet the pan was full of whatever before he started doing all this work.

 

[J JACKSON]

Re: gas spewing from hoses on valve covers

to answer you question on a holley carb if you leave the gasket off the power vale it will flood excessively install the gasket and drain the oil and be careful

 

[Don S]

Re: gas spewing from hoses on valve covers

Want to explain to me how the carb is connected to the crankcase?
Seems to me, if the engine was running that the gas would be going into the cylinders and out the exhaust, not into the oil.

 

[tinman565]

Re: gas spewing from hoses on valve covers

I'm gonna agree with Don. I think the motor would have hydrolocked before that happened. Same as leaving the jets out of the carb. Tons of fuel in = hydrolock..or fuel coming outta the exhaust (which I stated earlier). In order to get that much fuel (or whatever it is) in the pan (if its possible), and blow all that stuff out the valve covers..he would have had to turn that motor over for a week straight with no power valve gasket on it. Besides, if it was as simple as checking to see if the gasket was there (he was smart enough to remember about it )...dont you think he woulda looked before asking the forum ? I know I woulda.

Maybe all the ring ends mysteriously lined up, and the fuel is going into the pan that way....ooooooooooooo......spooky !!!!!!

 

[Don S]

Re: gas spewing from hoses on valve covers

Being a Vortec (as he said in the original post) it "Should" have an electric fuel pump.
And I agree, if it had a mechanical pump, that is how it would get into the engine.

 

[Fishermark]

Re: gas spewing from hoses on valve covers

The problem is the mechanical fuel pump, its leaking internally into the crank case.

Yep - That's really the only possible explanation.

 

[Don S]

Re: gas spewing from hoses on valve covers

I agree Don, but given what little info he made available I have to believe its the mechanical fuel pump. I just see no other possible way to get that much fuel in the crankcase. There just isn't any other place the two meet that could account for that much fuel. (Or at least none I've ever seen.)

I agree, that's why I said what I did in post #6.