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tchipman
09-09-2009, 08:41 PM
I have a 1992 prostar 190 it seems like there is a vapor lock in the carbs. if i let it sit then it goes away but the more i drive it the worse it gets. after a few minutes it won't idle. anybody wit similar problem?

JLeuck64
09-09-2009, 09:01 PM
hmmm, vapor lock.... reminds me of a good joke!

But seriously, what you're describing sounds more like a fuel starvation issue. I would be looking for a restriction some where in the fuel delivery side. After that you should make sure the pump pressure is OK and the volume is OK.

Slinkyredfoot
09-09-2009, 09:46 PM
This is an on going problem that I read a lot about here. I for one am going through the same BS and cannot seem to solve my problem either. My 351 starts acting up after and hour or more on the water, never before.

I talked to at least four very good boat mechanics over this past weekend about the almost exact problem you are having, and got four to 15 different opinions, vapor lock, fuel pump, carburetion, fuel, alternator, ignition, you name it.

After careful consideration of all the opinions, and you know what they say about opinions, I think in my case is is carburetion. I backed out the two idle screws on both sides of the Holly about an 1/8" counterclockwise and it seemed to help but did not completley solve my issue. I got it running better, but still not fixed. If I finally get it I will let you know bust it really Psss's me off

Hollywood
09-10-2009, 10:13 AM
Obviously you do not understand what vapor locking is. How many carbs you got?

thatsmrmastercraft
09-10-2009, 10:39 AM
This is an on going problem that I read a lot about here. I for one am going through the same BS and cannot seem to solve my problem either. My 351 starts acting up after and hour or more on the water, never before.

I talked to at least four very good boat mechanics over this past weekend about the almost exact problem you are having, and got four to 15 different opinions, vapor lock, fuel pump, carburetion, fuel, alternator, ignition, you name it.

After careful consideration of all the opinions, and you know what they say about opinions, I think in my case is is carburetion. I backed out the two idle screws on both sides of the Holly about an 1/8" counterclockwise and it seemed to help but did not completley solve my issue. I got it running better, but still not fixed. If I finally get it I will let you know bust it really Psss's me off

There are a lot of variables that come into play on a problem like this,, but use your experience with giving it a little more fuel guide you in the right direction. There may be several small problems ganging up on you here to make it harder to resolve the issue. You sound lean, but the mixture screws are probably not the place to go for the answer. Fuel delivery is one of the problems here....maybe a low float level or a bad float? You also may have a vacuum leak allowing more air in and making the lean condition worse. Have you pulled your spark plugs to check how your overall mixture is set?

Slinkyredfoot
09-10-2009, 11:29 AM
There are a lot of variables that come into play on a problem like this,, but use your experience with giving it a little more fuel guide you in the right direction. There may be several small problems ganging up on you here to make it harder to resolve the issue. You sound lean, but the mixture screws are probably not the place to go for the answer. Fuel delivery is one of the problems here....maybe a low float level or a bad float? You also may have a vacuum leak allowing more air in and making the lean condition worse. Have you pulled your spark plugs to check how your overall mixture is set?

Spark plugs look fine. Another opinion was a vent in the fuel tank, not sure on this one. I figure the vent to the tank could be the overflow. Is there another vent on the tank and does this sound like a possible problem?

thatsmrmastercraft
09-10-2009, 03:44 PM
Spark plugs look fine. Another opinion was a vent in the fuel tank, not sure on this one. I figure the vent to the tank could be the overflow. Is there another vent on the tank and does this sound like a possible problem?

Vent and overflow should be one and the same located on the port side of the transom. There would be worse things to do than to remove and make sure it is not plugged up. How old is the fuel line from the tank to the fuel pump? I have seen the inner wall of rubber fuel line separate and restrict fuel flow.

broncotw
10-30-2009, 09:17 PM
I have the SAME exact problem! Did you EVER find the solution to your problem???

TMCNo1
10-30-2009, 10:32 PM
I have the SAME exact problem! Did you EVER find the solution to your problem???

One way to see if it's vapor lock, is to wrap the entire gas line with aluminum foil (shiny side out) all the way from the fuel pump to the carb.
I had the same problem with a PCM 350 Chevy back in 1986 and it cured it and I never removed the foil for the 3 years we had the boat and it never vapor locked again.

blackcreek
10-31-2009, 03:32 PM
Vapor lock usually just causes hard starting due to heat soak after shut down as far as I know. Once the motor was running the cooling effect of the gas vaporizing in the carb and cooler fresh fuel coming in the vapor lock went away, at least that was how it worked on my boat.
I had vapor lock problems on a 275 HP chevy in a ski supreme. I slit fuel line length wise and insulated all the steel lines up to the carb then used a phenol block under the carb to kill heat transfer. They make them for just about all type carbs if you don't already have one. Worked like a charm. If all other parts of your fuel system check out you can give this a whack. I would insulate any exposed steel fuel line for sure, only a couple bucks to do that.
http://image.chevyhiperformance.com/f/10728730+w750+st0/0812chp_16_z+chevy_355_small_block_engine_build+op en_plenum_phenolic_carb_spacer.jpg