bertram31.com

yep...port engine wont idle. under a thou it just poops out. runs fine to 3000 but wont go past that under load. 4000 no prob in neutral. ive been starting in gear at speed but docking with one engine gets old fast.

good gas flow to the carb and its not ethanol disease...plugs look new.

help.

Will it idle in neutral? If so, but poops out in gear, it may be something draging in either the transmission or v-drive. Not a mechanic, so who am I to suggest...

You checked compression? Water in cylinder(s)?
Try adjusting low speed fuel mixture?

Randall it sounds like it could be sucking air "somewhere". Maybe an intake manifold leak, or the gasket under the carb. try tightning the carb bolts just a tad. Some times the gasket will dry out when not used for a while and suck air under the carb, causing the carb signal (vacuum) to be weak.

I assume you checked the fuel filter? That could also cause a similar problem. Maybe the small cintered screen at the carb is corroded or blocked.

If it was the fuel pump diaphram it should return fuel into the air breather, causing it to be too rich to idle. Pull the fuel pump return line off and see if it is pumping fuel back up to the breather.

Have you noticed "what" color the exhaust smoke is?

Randall

Make sure the throttle cable to that Carb is operating to capacity. That is it moves enough to fully open the Carb. Make sure the butterfly is not closing on you, i had that one time. Couldn't get over 3000 RPMS but it idled fine.

Also if it is a 4 barrell Carb. If it is make sure the back butterfly is operating.

Then like the Capt. said, check for something hanging up the prop etc.
Change the filters, and make sure you check the one in the Carb. That will do it also.

My first thougths parallel those of Scot.....a vacuum leak will adversely affect an engines idle....but not affect the top end as much.....

But I would take a good look at the ignition system....first of all make sure you have good power supply to the coil.

Then I would swap coils and see if the problem follows the coil.....I'm gonna put my money on an ignition problems.

Harry

thanks for the replies. gets plenty of clean gas and starts right up. spark to all cylinders....runs OK 1000-3000. bolts seemed tight but that was with a little wrench....ill put a socket on it it today. just hoping its gas or ignition and not compression or valves.

patrick....wont idle at all but will turn up to 4000 in neutral no prob.

patrick....wont idle at all but will turn up to 4000 in neutral no prob.

Do a vacuum test first...

Dirt / debris Clogging the Carb jet. I would have said water, but with the ethanol I don't think that happens anymore.

Coil would be my second guess, as Harry mentioned. Being that it is easy to check by swapping the coils, I'd swap and see if the trouble follows. Takes that right out of the equation.

Do a vacuum test first...[/quote]


how?

Randall,

Here's a simple trick, you could always try swapping the carbs on the motors, if you swap and the problem follows the carb, have it rebuilt. If not then you can start looking elsewhere.

br,
JohnD

Randall wrote:how?

You will need a vacuum gage.....get from a good autoparts store....not expensive.

The gage that I have also measures fuel pump pressure.

The gages are ususaly color coded....but I believe that good idle vacuum will be equal to about 28" Hg........I don't think that low vacuum will affect the high RPM as you are describing......

I am really interested in this thread Randall.....please keep us posted


Harry

i always try to solve problems by switching parts...its the beauty of two engines. ill keep you posted.

Randall-

You can get a cheap vacuum tester at an autoparts store. The owner's manual for your motors may list what the gauge should read at idle, and how it reacts to throttle. On my 454s, there's threaded bolt on the intake manifold a few inches behind the carb mounts that you thread out, and plug the gauge in there. I needed some kind of adapter from the threads to the gauge--like one of those fuel nipple things--but it was pretty easy to figure out. If you have a bad vacuum leak, sometimes you can hear them.

Check your timing--if she's retarded to far, you won't idle or make any power, but she'll run a bit in the mid-range. Same thing with bad spark to one cylinder. Run her as low as possible in neutral where she'll idle, and then pull plug boots off one at a time and make sure the idle dips. If you pull one off and nothing happens, you found your problem. I know you said you had spark to all plugs, but could it be a plug, and is it a strong spark to each cylinder? Weak spark to all--check coil and whatever else you can (points/condensor), weak spark to single plug = bad wire.

Not enough fuel would explain the lack of power, but not the bad idle--unless Scott is right about the pump.

So if you got spark and fuel, then I'd check compression. I had a motor that wouldn't idle and made no power--it'd just dog along in the mid-range. Turned out it had leaky intake valves and as such really low compression.

Hope its easy and cheap.

John

I'm not a mechanic, and didn't even stay at a Holiday Inn last night.

havent had much time yet but i did change the filters. it was ugly. then it started cold instantly and ran crisp. but still no idle below 1100. i tightened the carb bolts....ixnay. looks like an interesting weekend.

Randall,

I am no mechanic by any stretch. When I had my Chrysler 318's I had the problem of not making power past about 3000 as well. It ended up being the springs in the distributor. Little guys down under the rotor were all rusted out, one was even broken. That may have been the cause of some of the other problems I had as well. I ended up messing with jets to attain a better idle and top end but failed due to over looking the distribur springs. Keep us posted.

thanks kevin...i would never have thought of that.

Randall--

Easy way to check is to throw a timing light on, mark off on the harmonic balancer whatever full advance is supposed to be (maybe 28 degrees? don't know off the top of my head), and then run the motor up and see if you're getting full advance. I'm not sure that would explain the lack of idle though.

John

I would doubt that it was the spark advance springs if it is bad at idle, but one question, is it back firing? If the timing was bouncing around it would backfire. Sounds to me like a vacuum leak or you have dropped a couple cylinders. Could be as Patrick suggested, a drive issue and that motor is just loaded down over coming the friction. An old trick for the vacuum leak is a can of starting fulid, just give small shots around the manifold and if the engine races then you have found the leak.

I would as somone suggested, get it stable at 1100 RPM and pull 1 plug wire at a time from the plugs or distributor. if the engine does not slow down each time you know that cylinder is just along for the ride.

Starting fluid can be dangerous for finding vacuum leaks. Brake cleaner and carb cleaner will work but are also dangerous. WD40 is probably safest.

Randal I am with Rawleigh on this and it is not a vac leak. Idle jets What carbs do you have? Let me know.
Chris

carter AFB...4 barrels. electric choke which i have manually done with a little bungee cord for 11 years.

I would say idle needle and seats. Two ways to do this. One is run in the mixture srews and count the # on turns. This will alow you to put them back in and reset by backing them out to where they where. Once out spray carb cleaner and let set for a period of time. Foame carb cleaner I feel works better for on engine. Now My other method is a little strange. Fire up the engine and get warm. Take off flaime aresstor. With the choke full ope n bring up rpm to about 2000. At that point put your hand on the primary side and use your other hand to control the throttle linkage. Do not stall the engine as what you are doing is causing the primary side to run out or air. The engine will want to stall but do not let that happen. Bring the rpm up as needed. I have other ideas on this and the first two are the first two I would use .As a matter I use the second one first. Let me know.
Chris
PS If useing second method DO NOT use a rag to cover the primary

Chris: The hand over the carb is my favorite method of avoiding a carb rebuild on my older equipment. It usually works, but id what ever is blocking the jet is too large it just plugs it further.

Randall: I had my AFB's rebuilt by these guys 6 rears ago. They test run them and have a warranty.

http://www.carburetion.com/

thanks...

Yea
Did not want to bring that up or the spark plug switch and a backfire through the carb idea.
Got Watermelon Chris

all righty then !!....i sent the carb to carbs unlimited as suggested by Rawleigh. reinstalled and presto....idles like a champ.....i can shift a few hundred RPM lower then ever before and it dosen't stall. now i need help with the spring screw idle adjustment. i turned it all the way in and backed out two and a half turns to start. i couldn't sense any difference while playing around with it....what is the correct procedure for the two adjustment screws?

I do the same thing that you described.....only difference is that when you screw the mixture screw in you should hear a distinct difference in the way the engine runs.

Then back it out until the engine begins to running smoothly then do the same thing to the other screw.

I then go back to the first screw and do it all over again.....

If the engine is idled up to high the mixture screws that you are talking about will have very little affect. Make sure they are idling at 550 to 600 when you make the adjustment and that the ignition timing is correct.

Harry

I hope that fixes it for you Randall! Sounds like Harry has good advice on the settings. Maybe call Carbs Unlimited as well.

When you screw it all the way in...should sound like shes's gonna stall. Stop when you feel resistance. If the Rpm's don't drop it may be too fast an idle or debris ( just rebuilt, so I doubt that, but if it was remove screw and inject a shot of carb cleaner with that little stirrer straw or a shot of compressed air works if it was dirt )

As you rotate the screw outward to the 2-1/2 turns you will be looking/listening for the highest rpm. I like to use a portable tach for this, but not really necessary. You should be in the 2-1/2 turn range +/- a half turn or so and the difference is somewhat subtle until you know what your looking for. It may only be a few rpm so it takes an "ear". Rotate slowly.

If that don't do it Call Carbs unlimited as someone said.

not so all righty then......was pretty good at the dock and left the slip under two engines for the first time in a month. ran it hard for a few minutes and got the RPMs right up to where the secondaries should open, 3200RPM....but ixnay. the other engine has been like this for a few years but it idles. come in and the engine wont really idle and dies. rather than play around i docked the boat with one engine. hell if i ever get two it will seem pretty easy. any how i start er up in the slip and it will idle at about 550 but quite erraticlly with occasional self imposed jumps to 1200. not much available in between. if i try hard enough i can get 750 for a few seconds and shift but its not right.

soooooooooooooo?

From your fuel water separator. Pour all fuel into a clear glass. See if you have water. Look for water droplets or layer of water on bottom of glass. Take all gas on boat, fume precautions. You really should not have water in there with the ethanol, but really sounds like you have water in fuel.

Other then that I'm thinking a vacuum leak, check around the carb gasket and intake manifold. With engine running spray WD-40 around those areas and listen for rpm change.

Vacuum gage would work too.

Timing is good? Advances smoothly?





Boats...gotta love'em.

Sounds like vacuum and/or timing. Sim is on it. You now need to go back to the basics.

1. Check vacuum. If bouncing or low it could cause this erratic idle. Could be vacuum leak, sticking valves or worn cam lobes. this would also account for why you don't get any change from the idle screws.

2. Check timing. It could have jumped time on the timing chain.

3. While looking at the timing, are the bushings and/or advance weights in your distributor worn or sticking? A sloppy distributor can affect timing. Is it electronic ignition? Look at it after dark when it is running to see if you have a bad coil or coil wire. I found a friend's truck arcing from the side of an aftermarket coil to the bracket earlier this summer. It was a very tiny spark, but it was enough to make it run crappy.

OK ..im on it...... thanks

Randall-need a timing light? just holler. Walter

i think i all ready have yours...and the vacuum gauge...thanks.

Randall
I am gonna go back to my first thoughts and put my money on ignition system or something other than fuel system.

I am assuming that you have electronic ignition......

As far as the timing goes don't trust the marks on the harmonic balancer....pull#1 spark plug....stick a screw driver in the hole and slowly bar the engine over with a pull handle. As the piston comes up you can feel it with the screw driver. Keep going until the screw driver stops and starts going back down. Then reverse the rotation until you find Top Dead Center......the 0 degrees mark should be pretty close to the index pointer. If that works out then your timing should be correct when you check it with a light. But even at that the timing would have to be grossly out to cause this kind of problem.

I'm still thinking ignition system or internal engine problem

I think I remember you saying that you have the 318 Chryslers....is that correct?

H

360 heavy duty truck engines. heres the thing. after my last adventure i ran in 15 miles on the engine that wont idle. it ran strong and sounded fine till i tried to go under 1000 RPMs. pushing the boat alone at about 1500 RPMs it was fine.

OK shoot me now. i start up the port engine. starts in a nano second. sounds good. warm it up and bring it down to 1000 RPM. adjust the stop screw so there is a little slack and bottom the throttle at 750. purrs it does. so i start shifting and blipping trying to make it stall....wont. goes back to a nice idle.

then my wife comes running up to inform me the hot water heater is leaking like a stuck pig and the dryer is on fire........you cant make this stuff up.

we will see what happens tomorrow........other than buying new appliances.

Randall, You never told us about the water heater and the dryer.....

may be lint from the dryer plugged the flame arrestor....that's why it will not idle, then the engine backfired and ignited the dryer which melted the PVC line going to the water heater.....

Just screwing around LOL

H

what i want to know is where did he find room on a 31 for a dryer and water heater,

coolair wrote:what i want to know is where did he find room on a 31 for a dryer and water heater,

Even better.......... He found room for 'em on a B25.

LOL thats some funny stuff

i now have the cleanest most lint free dryer in America. i was hopin for a melted wire but no. spins nice...no heat.

bit the bullet on the water heater....new one tomorrow. 6 months free interest. what a deal......it only cost 3 times as much as the one i put in myself 30 years ago.

One step forward and two steps back.

Sounds like my life story....

exactly....i wont even start on my new medical insurance failing to give me a member number yet.......well the water heaters fixed anyway. by fixed i mean NEW.

Oh yeah...

well after a year in the making, I finally converted my 50 year old oil furnace to a gas fired unit.

Nice little unit, supposed to save me a ton of money, space and be real reliable.

Turned it on last night...well it saved me lots of money cause it didn't work.

Called plumber this morning, he said "it sounds like something is wrong".

ding ding ding....we have a winner (i hope). and the winner is harry.

found an ignition wire that was frayed and grounding on the manifold killing that cylinder. left and returned to the dock on TWO engines.

(OK someone else found it)