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View Full Version : Carb adj causing fast stalling???????


peterb
08-09-2006, 12:09 AM
Ok, here's the problem, other than I am leaving for vacation on Lake Cumberland starting Sunday and desperatetly need to fix my boat....

My 86 with a 351 is still stalling at 35+... starving for fuel it appears.

So far, I have:

- Drained the fuel tank and cleaned it out
- Checked the pickup hose
- Rebuilt the 4160 carb
- Replaced the anti-siphon valve at the top of the tank (severely plugged)
- Checked all the fuel lines
- Replaced the fuel/water seperator filter
and finally, today....
- Replaced the mechanical fuel pump

I am out of ideas other than.... could something be amiss with the rebuilding of the carb... the float adjustment, needle valves, something.

I am at a loss...

kurtr
08-09-2006, 12:59 AM
Is your tank vent line open? A clogged vent could cause a fuel starvation at high speeds.

peterb
08-09-2006, 10:15 AM
Vents fine.. even ran with the gas cap off to make sure.

Bruce Carr
08-09-2006, 12:31 PM
Try running a new (temporary) fuel hose directly from the anti-siphon valve to the fuel pump. This will eliminate any variables between the tank and the fuel pump. If it runs out OK, you will know that the old fuel line is restricted in some way or there is a problem in the filter.

If there is still a problem, try loosening up the distributer a little and manually adjusting the timing (by rotating the distributer) when the engine is at speed and stalling (35MPH). This could help in isolating a potential timing advance problem in the distributer.

Do you still have points? If so, they may be "floating" at higher RPM if the spring is weak, or cracked.

Just some ideas to check out.........

peterb
08-09-2006, 02:00 PM
I can try the fuel line issue... it's the only thing not replaced but it was blown out with an air line.

You refer to a filter, the only one I have is the fuel/water seperator mounted on the stringer next to the engine. That has a new filter element this year and I checked it yesterday, it looks clean. There is no other filter I can find.

The timing is a bit off and when I tried timing it before, about a week ago, after I redid the carb, it ran better where it was then trying to get it back in sync.

The plugs, points, condensor, wires, cap, & rotor were all replaced last year. I had to do the points again this year (it wouldn't start at the beginning of this year). I didn't do the condensor because the one I got from West Marine was the wrong size.

It ran a bit rough so I replaced the plugs... that didn't help.

When I replaced the fuel pump yesterday, I did get the right condensor from a MC dealer and replaced that. It now idles lower like it should and doesn't seem to misfire as bad. I also reset the points at that time.

I looked at the dist weights and springs and seeing how that was the first time I looked at em, they looked and seemed to move fine.

I was sort of ruling out timing and ignition because it seemed to run fine at lower speeds and I figured if it was an issue with one of these, it would faulter then as well.

I have considered electronic conversion but I have sunk so much into this boat this season... the funds are running thin. Hell, I haven't even run much more than a tank of fuel this season. I figure I'll make up for it in Cumberland but this is frustrating and I am running quickly out of time.

xsvfooter
08-09-2006, 03:53 PM
Are you sure it's fuel starvation? Next time it stalls, before you crank the motor. Check to see if there is fuel in the bowl. You can check in the hole used to adjust the floats. You might have someone pump the throttle a few times to see if fuel is squirting into the carb.

Bruce Carr
08-09-2006, 04:11 PM
Describe the symtoms again. At speed does it begin to get ragged and then loose power and and then keep running roughly or does it simply shut die when the magic power level (RPM / speed) is reached?

Does it accelerate normally up to speed?

east tx skier
08-09-2006, 04:12 PM
Don't forget to clean out the flame arrestor. Never hurts.

peterb
08-10-2006, 01:46 AM
Flame arrestor was cleaned out thoroughly. We even ran with it off to watch in the bowls.

When the boat hits approximately 35 mph and sustained (or higher)... after a 10-15 seconds it starts sputtering and reving then if we leave the throttle alone, dies all together.

We know it's starving because we can maintain the engine running by spraying starter fluid down the throats when it is sputtering.

If we back off to an idle or much much slower speed (10mph), it levels out and we can go back up to speed. Pumping the throttle sometimes produces a backfire when it is sputtering so we avoid that.

Not sure what "hole" is referred to for "adjusting the floats"... I don't believe the 4160 Holly Carb has that capability. I think the only way to adjust the floats is to take the bowls off the carb.

My other concern, I can run at 30-35 without hesitations, etc... but if I am having this other issue at higher speed, is there a chance that the "normal" running is not good for the engine?

Hoff1
08-10-2006, 09:00 AM
...I haven't even run much more than a tank of fuel this season. I figure I'll make up for it in Cumberland but this is frustrating and I am running quickly out of time.
You'll make up for it at Cumberland for sure, gas was $3.75/gallon there last weekend.

I can't say I've had high rpm stalling as a problem, but I have had low rpm stall problems. I would definitely check the timing again, that fixed a lot of my problems that I thought I was having (after the second time I timed it). When you get it set at idle, check to see if the timing advances/retards when you give it gas (not sure which direction it goes). If not, it could be the spring in your distributor - total guess but sounds right.

With it strictly happening at 35 and above, it is right where the secondaries kick in. Could the power valve not be sized correctly? I've ran a 6.5" with good success.

Bruce Carr
08-10-2006, 10:06 AM
Sure sounds like gas starvation to me. You need to start isolating the problem as you are running out of time. Try this:

Get a new piece of fuel line (3/8" ID) about 4-5 feet long. Disconnect the existing fuel line at the pump (plug the end so gas doesn't run out) and connect your new 4-5 ft long hose to the fuel pump. Stick the other end in a 5 gal gas can maybe half full so it does not slosh out when the boat is moving. Take the boat out to the lake and run it up to full throttle.

If the engine doesn't stall out as before, you know your fuel pump, carb, ignition, etc is OK. The problem would have to be either in the fuel line, the filter, the anti siphon valve, fuel pick up tube in the tank or vent system. My bet would be a restricted fuel line seeing as you have replaced/checked everthing else.

If the engine continues to stall, with the hose in the gas can test, you know you either have a fuel pump problem (nor delivering enough pressure or volume), some restriction in the fuel line to the carb or the carb itself. Possibly an ignition problem or engine mechanical problem but I doubt it because you said the engine would recover if you shot starting fluid down the carb.

While the engine is in its sputtering mode, manually hold the secondaries closed. If the engine recovers somewhat, you have probably isolated the problem to the secondary circuit.

It's possible that the needle in the primary bowl is not opening up all the way (float travel restricted) resricting fuel flow into the fuel bowl, or there is some debree clogging the seat. If you can isolate the problem to the carb, take it apart and clean it out with a spray can of carb cleaner followed by some compressed air.

Good luck and report back!!

xsvfooter
08-10-2006, 03:28 PM
Peterb, grab the holly rebuild pdf from the holley website. On page 6 is a picture and procedure described to adjust the float setting. There are two methods, one while the carb in on the motor (wet method) and one while the carb in off the motor (dry float method). There is a sight plug port that the gas should be level with. When you rebuilt the carb, are you sure the gaskets on the metering block where correct and in the right orientation?

peterb
08-10-2006, 11:43 PM
Boy, I don't think my carb has the external adjusters... I just can't see em. Do you know the filename location of that PDF. I can't find one on the site with 6 pages for the 4160.

As for the gaskets, there were a couple of them and we used the one that matched the old one and made sure that it wasn't covering any holes or openings. That was one thing we double and triple checked.

the one thing I remember about the gaskets... I can;t remember off the top of my head if it was the primary or secondary metering gasket, but the one side that had the "bowl" shaped indent in the plate, the old gasket followed that contour. The newer gasket did not, it was flat... it matched perfectly except for that. There wasn't one that had that "indent" in it. We figured it stretched either over time or as needed or that was the one reason we were having so many other problems before the rebuild.

xsvfooter
08-14-2006, 04:31 PM
See attached

Hoff1
08-14-2006, 04:59 PM
the one thing I remember about the gaskets... I can;t remember off the top of my head if it was the primary or secondary metering gasket, but the one side that had the "bowl" shaped indent in the plate, the old gasket followed that contour. The newer gasket did not, it was flat... it matched perfectly except for that. There wasn't one that had that "indent" in it. We figured it stretched either over time or as needed or that was the one reason we were having so many other problems before the rebuild.


Are you saying that both of the gaskets you got with the kit looked like the one on the left. I believe this is the way all of the kits come. Iíve always had to cut the half moon in mine to have them fit correctly on the side where the power valve is at. If you didnít do that, maybe thatís a cause of your symptoms.

rsmith_5568
06-20-2010, 02:03 PM
I have an 86 with the indmar and a 4160. Had carb re-built last year and everythingok till this year and the 35 mph stalling started this year. The only thing i did different this year is change plugs. When i started to have problems with the high speed stalling i installed a new fuel filter and still prob was just getting on here to see if anybody else had that prob.. Sucks runs great at low speeds but it will let me hit about 42 mph for a couple os seconds then it stalls out. I will keep my eye here and if i get it figured out will let u know:confused:

ecproductions143
06-20-2010, 02:19 PM
[QUOTE=rsmith_5568;687922]I have an 86 with the indmar and a 4160. Had carb re-built last year and everythingok till this year and the 35 mph stalling started this year. The only thing i did different this year is change plugs. When i started to have problems with the high speed stalling i installed a new fuel filter and still prob was just getting on here to see if anybody else had that prob.. Sucks runs great at low speeds but it will let me hit about 42 mph for a couple os seconds then it stalls out. I will keep my eye here and if i get it figured out will let u know:confused:[/QU

has it backfired at all since rebuild? also did you use stablizer in the fuel and run it thru the carb. These hollys are a real pita sometimes but when you got it right boy are they nice. If you have backfired it since the rebuild then you prolly poped the power valve. Easy to replace. just make sure you get the right size. Maybe someone will chime in and let us know I wanna say its a 5 or 5.5 maybe. I put a glass ghas filter right before the fuel goes into the carb that way i can see what the gas looks like. I had water in my gas last year and it was doin the same thing drained the tank and put some fresh gas in. It was my fault I didnt fill the tank uo before winterizing and a little condensation cuased the stalling when you got on it.

PS nice resurection of a 4 yr old thread lol. Thats what I like to see someone who is useing the search :D

rsmith_5568
06-20-2010, 02:24 PM
i have not had any backfiring and i have also fille tank at least 3 times and yes i run sea foam in every other tank

oldairboater
06-20-2010, 02:35 PM
Check needle valve and secondary diaphragm on secondaries. My secondaries open at around 3200 rpm. I had the same problem with my Holley. At 35 mph the boat would fall off and run bad but still jump out of the hole and cruise as long as I didn't hammer it. I did a couple of things and I am not sure which one solved the problem. I adjusted the needle valve and manually exercised the secondaries. Something worked--because boat now runs like a scalded cat.

rsmith_5568
06-20-2010, 02:38 PM
so you think it is in carb? That would suck because i had it re built last year

oldairboater
06-20-2010, 02:46 PM
Somethings is either plugged or stuck would be my guess without actually listening to it. I like Holley's. I run Holleys on a few other boats that see hard use.

rsmith_5568
06-20-2010, 02:56 PM
thanks will try those few things.

thatsmrmastercraft
06-20-2010, 04:42 PM
Have you pulled a couple spark plugs to see what color they are. That will sure give you a good idea on what is going on.

loeweb
06-20-2010, 07:13 PM
I am having similar problems in my 88. Around 3800 RPMs with a skier I was having this problem. My emphasis is on the skier. I was only having problems when he pulled out hard on his left. I also had a couple of buddies in the boat. This is leading me to think that I am having a carb issue. I think that I am not receiving enough fuel to the secondaries and when the boat tilts hard one way or teh other, it is starving for fuel. How do I adjust this? is there an adjustment screw I need to loosen a little or what?

thatsmrmastercraft
06-20-2010, 10:34 PM
I am having similar problems in my 88. Around 3800 RPMs with a skier I was having this problem. My emphasis is on the skier. I was only having problems when he pulled out hard on his left. I also had a couple of buddies in the boat. This is leading me to think that I am having a carb issue. I think that I am not receiving enough fuel to the secondaries and when the boat tilts hard one way or teh other, it is starving for fuel. How do I adjust this? is there an adjustment screw I need to loosen a little or what?

Sounds like it could be a fuel delivery problem. How does it respond on a long full throttle run? Could be a clogged fuel filter, fuel pump, partially sunken / out of adjustment float, bad power valve, bad secondary diaphragm to name a few possibilities...........if it is fuel related.

glassmaster
06-20-2010, 10:48 PM
I am having similar problems in my 88. Around 3800 RPMs with a skier I was having this problem. My emphasis is on the skier. I was only having problems when he pulled out hard on his left. I also had a couple of buddies in the boat. This is leading me to think that I am having a carb issue. I think that I am not receiving enough fuel to the secondaries and when the boat tilts hard one way or teh other, it is starving for fuel. How do I adjust this? is there an adjustment screw I need to loosen a little or what?

I would say that it is a float problem if the boat tilts hard in one direction and it starves for fuel.
Just take off the bowl and bend the tab with a screwdriver to make sure the float is parallel to the bowl. While you are in there make sure the needle valve does not have any indentations from the seat or residue on it.

loeweb
06-20-2010, 11:01 PM
Sounds like it could be a fuel delivery problem. How does it respond on a long full throttle run? Could be a clogged fuel filter, fuel pump, partially sunken / out of adjustment float, bad power valve, bad secondary diaphragm to name a few possibilities...........if it is fuel related.

It runs fine on long runs at high speeds (38-WOT), but it acts the same when the boat is turned quickly at high speeds. Not like I turn the boat around at 43 MPH, but a short jerk of the steering wheel causes the boat to respond the same.
I have replaced the fuel filters and power valve, have adjusted the carb a couple of years ago, but this symptom has just recently appeared. Any help is appreciated, thanks all.

ecproductions143
06-21-2010, 02:49 AM
i know this may seem unrelated but a buddy of mine was having some crazy issues like that as soon as the boat warmed up. Turned out to be alternator. was pushing out 13.x then once it got to operating temp it was only putting out 9v of course this should be easy to tell as you would have gas on the plugs. You can check it with a volt meter just to rule out that possibiltiy.

thatsmrmastercraft
06-21-2010, 10:17 AM
It runs fine on long runs at high speeds (38-WOT), but it acts the same when the boat is turned quickly at high speeds. Not like I turn the boat around at 43 MPH, but a short jerk of the steering wheel causes the boat to respond the same.
I have replaced the fuel filters and power valve, have adjusted the carb a couple of years ago, but this symptom has just recently appeared. Any help is appreciated, thanks all.

Sure could be a low float level - or at least a low fuel level.

Just a thought.....how does it act when it stalls? Does it cough and stumble, or does it cut out like it could be electrical? Like a wire being pulled with the torque of the engine.

loeweb
06-21-2010, 04:21 PM
it basically cuts out, and eventually comes back. I wouldn't say it stumbles, just cuts out all together. On high speed runs, it loses power in a similar fashion, but happens on either side turn not just left or right.

thatsmrmastercraft
06-21-2010, 05:29 PM
If it is cutting out rather than stumbling from lack of fuel, you might have an electrical / ignition related issue.