Gearheads.. I've got a one pump chump!!!

1987 American Skier
Ford 302 with a holly 4 barrel carb.
Mallory ignition

Well, I just got off the lake for the second time with a broken boat. The first time, it acted as if I had run her out of gas even though I was showing a quarter of a tank of gas. I filled her up on the way home and she started fine in the driveway. When I was out today, she initially started fine, but a little rough. After I revved it up a little it ran perfect. Once the engine gets warm while pulling the first wakeboarder, it dies when I go back to idle to pick them up. It is un-savable. I tried to catch it as it was dieing, but I am unable to. It dies even though I am giving it gas. I even tried bringing the RPMs down slowly to about 1300, but she kept falling no matter what I did. I am unable to start it until it cools down, and then it runs fine (especially at high speeds) until it heats back up again. I went through this cycle 4 times this evening. Does this sound like a carburetor issue? I had it rebuilt 2 years ago and I have never had a problem. I am definitely getting gas in the carburetor, so that is not the issue. When it is working it is running quite rich, and the back side of the butterfly valve is sootier than normal. I’m stuck. The coil appears to be getting hotter than I remember, but I have never really felt it after I was done running it for a while.

take a can of carb cleaner and check for vacuum leaks...by spraying between the intake and carb...and intake and block

vapor lock maybe?? check to make sure the fuel lines are not close to anything too hot. just an idea.

I was going to suggest vapor lock as well, but wasn't sure if it happens in boats......

Do you have an in tank fuel pump, or engine mounted one? I've had similar symptoms with an electric pump. When it got hot it died, and after cooling off for a while it would start again.

(Message edited by bstroop on May 02, 2006)

If you have a water fuel separator check that... when mine was full of water i was fine at high throttle. dump it and fill with fresh gas

I have an engine mounted fuel pump.

It could very well be vapor lock, but that would be kind of odd, because the fuel lines are in the same place they have been in forever and we never had this problem before. That is not to say that it can not happen. I will check for that. I just got done reading online about vapor lock.

They said to try a different type of gas... done

They mentioned to find the gas lines and make sure they do not cross any hot spots...

They also mention that there will not be any gas in the carb if it was vapor locked and we seem to be getting lots'o'gas. You can see it spraying. It also runs perfect at high RPM, but dies at low RPM and will not restart. Correct me if I am wrong (I am still learning) If I had vapor lock, it would also run rough at high RPM…


Another thing is that it really is running a bit rougher than it use to even in idle. It is like all of the sudden this issue happened and it is not going away.

Cliff~

When you mention taking a can of carb cleaner and checking for leaks, are you meaning where the carb attaches to the block. Right around that seal?

yes I am
perhaps as the engine heats...a leak gets worse
the carb cleaner will let you see bubbles, indicating a leak
just spray it around all of the engine seals while it is running....won't hurt anything

when you are spraying, do it while the engine is at about 1000-1200 rpm. If you have a leak, the engine should rev.

i would definately check for water in the gas. that would explain why it runs rough, and wont idle. Those things need to be cleaned out and/or replaced every so often.

nbeihl,

I troubleshot this exact same problem for years on my older IO. Though mine wasn't consistant everytime - It'd act up every now and again. Here's the two things I ended up with.

1) Points, replace and or adjust the points

2) I began to notice that when it'd act-up, that if I ran back to the engine after it died and pulled the air cleaner, I could see gas running out of the float bowl and into the manifold. I have two explanations for this:

2a) I had a steel fuel tank. The boat had sat for many years. The tank had rusted. Rust particles were making their way up through the inline fuel filter and they'd get stuck on the needle valve in the carburetor. When they'd get stuck, the needle valve couldn't seat properly. Thus, at idle the float bowl would fill up and overflow into the intake manifold. The engine would go rich and die. A quick test for this would be to cut your fuel line and install a clear fuel filter. (assuming you have a metal gas tank) If the filter gets loaded up with rust particles, they may be your culprit.

2b) carburetors were designed to go on cars. Cars sit (mostly) level and rarely experience a lateral G loading of more than .6. with a boat, you're commonly banking into corners and generating G loading to exceed .6 Gs. I suspected that the Needle valve would get dislodged and jam into the side of the seat preventing a firm seal. thus, flooding the carb and dumping the overflow into the manifold.

One of the remedies that I figured out was this; when it'd die I always had the excess of fuel flooding into the intake manifold. So I'd park the boat with the throttle and wide-open and the aircleaner off. That way the excess fuel could evaporate quicker out of the hot intake manifold. It seemed to get me started quicker.

I replaced the coil-nothing, and many fuel filters-seemed to help. I rebuilt the carburetor sometimes twice a summer-always worked for a little while. I pulled my hair out trying to solve this problem. I got so familiar with the carburetor, that when it'd die on the water, I'd pull it apart and clean the needle valve and seat with a cue tip. I could do this process in about 10-15 minutes at my best. Though unsafe, I did this probably 20 times. Never the less, it impressed my first-time on the water friends. They'd realize the gravity of the situation being stuck on the water then I pull some magic mechanical trick and we're running again...they thought I was god. :-) haha..

Anyway, good luck, keep us posted.

Check the float levels, it easy.

another for vapor lock. make sure the hose from the gas to your carb isnt near anything hot.
also take the carb apart and clean it out. im not very mechanical and i have no problems doing this task

I just got finished rebuilding my Holley 4150 (4 bbl, double pump) - took about 6 hours - makes ALL the difference in the world as far as idle smoothness, lag on acceleration, not starting after being warmed up - hey, for $50 and some time, I'm a happy camper - if you've done your due diligence on the elctrical side, I'd just go ahead and do the dang carb...this of course assumes you're getting a sufficient amount of good clean fuel to the carb...

(Message edited by wesgardner on May 03, 2006)

nbeihl
lots of good advice on this thread...

I also wouldn't rule out vapor lock

everybody here makes great points

I wonder what a fuel injection kit would cost...might be worth the money

good luck

COuld be the fuel pump itself. They have a rubber membrane that gets brittle. They are rebuildable but replacements are cheap. Also, do you run, or has the boat ever been run in a sandy bottom lake. If not, I won't bother you with my experience with the very same problem.

Did it ever backfire through the carb? Sure sounds like a power valve which would cause it to run rich and not run at idle or just off idle but run fine in the higher RPM's. Also it will run better cold than hot as it needs more fuel cold. You should see black soot coming out the back if it is the power valve.

Get water to the engine and run it on the trailer. Warm it up until it acts up. At this point you can use the carb cleaner down the throat of the carb to see if it will run off the carb cleaner. If it does that would indicate a lean condition. If it stalls and will not restart, set the throttle for wide open and try to start it again. It may take a few time cranking it (Never more than 15 seconds at a time with time between to allow the starter motor to cool). If the motor now starts it is flooded. Make sure you are quick to cut the throttle back as you can over rev the motor.

BTW to correct miss information. Typically vacuum leaks get smaller as an engine heats up. It has more effect on runability though as they run leaner without the choke on.

nbeihl:

Is your carburetor the "double pumper" type, that has two seperate float bowls? If so, then it is possible that one float bowl is having a problem, possibly because the screen at the intake (right on the carburetor) is clogged. If this happened on the primary side then it could run out of gas under load but the engine continue to run off the secondaries alone. Once you back the throttle off and close the secondaries then you have nothing. The accelerator pumps draw from a little lower in the bowl and have a bit of reserve of their own so a few pumps they would squirt.

A situation very similar to vapor lock is an air leak in the fuel line between the tank and the pump. A crack in a rubber hose or the seal on your fuel filter/water separator could cause the pump to suck air. A full tank would be easier to draw from than a 1/4 full tank so it would vary with fuel level. A cool pump handles air better than a hot pump so temperature would have an effect.

Can you easily get to the flame arrester on top of the carb? If so, carry a can of "starting fluid" with you. When it won't start, give it about a two second shot of starting fluid right in the flame arrester screen and then try to start. If nothing happens then you aren't gettng spark! If it starts up then dies right away then you aren't getting gas.

If you have any suspicion on the coil then I would just change it. Same with points and condenser (if your boat has them). Heck, change the spark plugs while you are at it. The coil and condenser are both things that can get weak with temperature and could possibly cause such a problem. They are also easy and cheap to replace, and well worth the cost if if eventually saves you a day of riding.

If you want to absolutly rule out vapor lock or fuel delivery issues then the thing to do is to cut the fuel line between the pump and the carburetor and insert a TEE. In the third leg of the Tee put a pressure gauge (15 PSI max). I would expect fuel pressure to be around 5 or 6 PSI, but what you are really looking for is a sharp decrease in pressure when the problem occurs.

Peter
you're right
good call

hey guys, this is nbeihl's wife...
my... do we have a probelm on our hands... but it seems with all of this good info we'll be back on the glass in no time
thanks for all of the tips, this is helping him sleep better at night!!!
nbeihls wife

It looks like I left my computer up and the wife posed… She knows that I am going to figure this thing out no matter what it is!!!

I went through and checked the fuel filter / water separator, and it appears as though there is nothing but good gas in there.

I also checked the fuel lines for a possible vapor lock, and the rubber fuel lines are completely separated by a decent distance from the engine. After the rubber goes into the mechanical fuel pump, it is pumped through a metal line to the carb

I am going to do the points and condenser and check the spark plugs for anything fishy. I will get back with some updates to the diagnostics Saturday when I get time to jack with it.

Eric fox~
My boat is run on a river that is quite dirty / sandy. More mud than sand. What is your story, perhaps I can learn from it.

I am also going to take the fuel pump apart just to look at it. I have had the boat for 3 years and have never even bothered to look at it.

Wes~
I am thinking about rebuilding my Holly 4150. I would consider myself mechanically inclined, but I have been fearful of carburetors up to this point. It appears as though it is not that hard. When you rebuilt yours did you just replace all the rubber, seals, and clean everything?

I rebuilt the Holley on my 1983 Nautique, it was my first and it was pretty easy. I just followed the instructions that came in the kit from Napa. It took about 4 hours one afternoon from first bolt to smooth running. Once you get this sorted out I would suggest installing the points replacement type of electronic ignition (I think it's about $100 from Overtons). That boat ran much better than new once the carb was rebuilt without the points. It started with a tiny bump of the starter.

I was going to mention the spark plugs. It's a shot in the dark but a quick check. I've been told that plugs that have too much gap will give a hot engine problems. Probably not your problem, but like I said, it's something easy to check.

" I am also going to take the fuel pump apart just to look at it."

If it ain't broke don't fix it.

Do check the plugs mostly for color. If they are black you are running rich. White means lean. Get the idea? Really you should only have to pull the easiest plug. They will always be somewhat black around the outside edges that is normal, look at the center of the plug.

I have yet to see a boat vapor lock, but that doesn't mean it doesn't happen. They tend to run much cooler than a car and even then few cars ever vapor locked including vehicles from the 60's.

You need to determine if you are rich or lean and take it from there. Ignition probably doesn't have anything to do with it as temperature would not affect it as much.

nbeihl,

Yup - I just got the "Renew" kit - it gives you new power valves, accelerator pump, gaskets, etc...I think a big component is just cleaning it up making sure everything is where it should be, someone before me had the jets in the wrong place - you can get the small red Holley handbook if you want some background reading, here are a couple of links I found helpful...you CAN DO THIS THING...

http://www.barrygrant.com/fromBarryGrant/BG%20Instructions/carb%20rebuild%20kit4150.pdf

http://www.fordmuscle.com/archives/1999/12/holley/index.php


I'm sure folks here will talk you thru it if you get stuck - call skiDIM with your "List" number and they'll get you the kit for around $50.


Check out the Holley 4150 rebuild/Jetting thread - Aaron gave me some VERY good tuning tips...

I would also invest in the electronic ignition module for your motor rather than points...

(Message edited by wesgardner on May 04, 2006)

(Message edited by wesgardner on May 04, 2006)

DOH! Call Vince and SkiDim - 803-345-0996.

If anyone can tell you where to look its Vince. He's seen it all and fixed it all.

I had a bogging problem on my 84 Supra, I called Vince and he said to clean out the Super Traps. After he explained what they were and how to clean em, I was in great shape.

Give him a ring and see what he says.

Well, I had the electrical ignition and that was the problme. The magnets that go past the sensor came unglued. I also changed the coil and we are 'money'.