1997 Volvo Penta 4.3 GS Very rough at low rpm and dies if brought back to neautral

[jrgcbg40]

Hi, I just took my boat out of winter storage. It started up quickly and I ran it about 1500 rpm for a few mins. When brought back to idle position it was really rough and died.
These are the specs on my engine. 1997 4.3 GS PLKD 4 barrel holly carb. This will be my 3rd year with the boat. I winterized it by opening the block drains and all hoses from waterpump and took out the thermostat. I then filled the hose to the waterpump with antifreeze 50/50 green car stuff. (the year before the pink stuff looked like a slushie in my rv toilet so thats why I opted for the green.) I then re-installed the hoses and therm housing. Put the muffs on and had my son start pouring in the antifreeze through a section of garden hose and funnel. I started the engine and he poured 4.5 gallons of the green in. I then fogged it and let it stall. I always keep fuel stabilizer in the gas. I tested the antifreeze in the catch bucket and all the ball floated so I figured it was good. I didn't re-drain the block this time as I thought it would be better for corrosion purposes to leave the anti freeze in. I also changed the oil and fuel filter. My fear is something went wrong and maybe I cracked the block or heads?

So for testing I replaced the spark plugs, drained and refilled the gas tank and re-installed the thermostat. Did a re-start and it started right up again but still had the rough running at rpms below 1000 and died when put in neutral. I sprayed carb cleaner in while it was at 1500 rpm. Let it run to operating temp (about 15 mins) then tried to bring it to neutral and it stalled.

My next step was going to replace the distributer cap and rotor as I don't know if or when they were changed. But after looking at my photo's I saw one plug that was cleaner than the rest. Making me think it maybe a head gasket or riser problem?

I did a compression test with a cold engine and throttle full open. Results #1 190 psi,#3 190psi, #5 190 psi. #2 180 psi #4 180psi # 6 170 psi. I did # 6 twice just to make sure I turned the tester in tight enough and it tested at 170psi again. So its an 11% variation from the 190 to 170?? Is this bad enough to cause my symptoms? The carb was also rebuilt twice by the boat dealer because they said there was junk in the tank. last year I added a stiffer spring to the secondary because I had a bog on accel and that fixed it. Boat ran fine before putting away?? Which direction should I go now? Thanks in advance for your help.

 

[bruceb58]

Your compression numbers sound good.

Did you drain your manifolds when you drained your block?

Did you replace your spark plugs with new ones?

BTW, putting antifreeze through the muffs is a waste of time. It never reaches your engine. Just goes out the exhaust.

Out of curiosity, what are you doing with the antifreeze when it reaches the ground?

Spraying carb cleaner in the throat of a carb doesn't do anything.

 

[jrgcbg40]

I pulled the two drain plugs on the block and also the plug on the intake manifold. also the one on the circulating water pump.is there another drain for the exhaust manifolds?
yes I did replace the spark plugs.
I used an oversized square transmission pan funnel into a round catch pan and drained it back into the bottles after it was done.
what would you look at next, should I go cap and rotor?or do you think its a water intrusion problem?
It revs up good held it at 3000 rpms for a few seconds and it was smooth. Then slowly backed it down to near idle and it runs rough and stalls if put back to neutral.sounds like it could be misfiring at that low rpm? Also the engine has 462 hours on the clock.
Thank You

 

[bruceb58]

You just pull the hoses on the manifolds to drain them.

Wouldn't hurt to do the basics like coil/wires. Verify timing.

I doubt you have a water intrusion issue but if you do, it is your manifolds and that shouldn't cause an idle issue anyway.

Check your firing order to make sure you put the wires on correctly. It is amazing how smooth an engine will run under no load with 2 wires crossed.

Next year when you winterize, drain everything and just leave it. Forget the antifreeze. If you insist on doing it, leave the part out where you run on the muffs.

 

[jrgcbg40]

ok I'll do a coil, cap , rotor and wires and check timing.I'm pretty sure the firing order is correct because I didn't change it. I changed the plugs after the symptoms were already there And did the plugs one at a time I'm hoping its not anything cracked in the motor. The stumper is it ran perfect when I put it away. I also put a fuel pump in last summer mid season and cleaned the anti-siphon valve in the tank.I also checked the tank for debris and didn't see any. The fuel looked a little bit yellow so I drained it and put in fresh gas, then jump the fuel pump till the gas came out clear.
Thank you

 

[Lou C]

I agree you comp test #s are good. Plugs look fouled though, could be fogging oil but after I start mine after winter storage and burn off the fogging oil they usually look much lighter in color than that. If you put in a new set if they still look like that you might still have carb problems (choke not opening, sticking float, etc).
I do fill mine up with -100 AF but I do it the way Merc and OMC say to do it in their manuals-- manually drain, poke all holes, replace drain plugs with a bit of gasket sealer on the threads and back fill through the hoses. BTW you do NOT need to remove the thermostat to do this; just disconnect the big hose from the top end at the thermo housing. Then stick a funnel in it and fill it through the hose till it comes out the neck of the thermo housing. Re connect the hose. Manifolds, I fill em till I hear it run out on the ground (why you must use no tox).
Post back what you find next...

 

[jrgcbg40]

That's encouraging,so if compression is in spec then chances are good that there are no cracks? I pulled the thermostat housing because I was having issues with rust particles sticking The thermostat open.I also read somewhere that It was the easiest way to get the antifreeze to flow through the engine when winterizing.I thought leaving the antifreeze in would cut down on the corrosion.the water drained pretty easily I did still poke with wire in there but nothing bad came out.I took off the flame arrestor while it was running and the choke seem to open as it should. my son is going to pull The carb see if there's anything going on there.
Thank you.

 

[Lou C]

The easiest and best way to use AF on a raw water cooled engine is to manually drain and back fill. Since you removed the 'stat, you should have not had a problem with water left in the block. That can happen with the suck up the drive kits if the stat does not open all the way.
Did you take off the big water separating fuel filter and dump it out in a big jar and let it sit? See if you have water or other junk in there.

 

[jrgcbg40]

I changed the filters as part of the winterizing process. I emptied the old filter on to a white paper towel to check for particulate but I didn't check for water. the fuel was slightly yellow when I took it out of storage. so I drain the tank and put in fresh fuel. then I jumped the fuel pump until all the clear fuel came out.I tested the yellow fuel in the lawn mower and it seemed to be fine.I ran the boat for about 15 to 20 minutes afterwards that should be enough time to drain the bowls yes?
Thank you.

 

[nitwhit]

My 2 cents with the parts cannon is on the carb being gummed up or having trash in it. Sure won't hurt to look at the cap and rotor though.

 

[jrgcbg40]

I replaced the cap and rotor today. The distributor shaft was kind of rusty so I wire brushed it and blew some compressed air to it. I then coated the shaft with a very thin film of dielectric grease. I put on the new parts and started it up.The boat ran great for about ten seconds then started to stumble and loose rpm.I took off the flame arrestor to check if the choke was opening/stuck .It was opened. When I looked down into the carb I saw gas dripping out of the left side venturi is it called? But nothing on the right side? Which is it supposed to be? What would cause this problem? How should I go about repairing it? I will try to attach a you tube link of the leaking carb.At the end of the video is when I put the throttle lever back to center. (Neautral) Could this be my stalling problem?
Thanks to everyone for the help!

Link to video https://www.youtube.com/watch?v=GyM5YWvzbjw

 

[Lou C]

You need to get that carb rebuilt no way raw gas should be dripping out like that. Explains your fouled plugs.

 

[jrgcbg40]

Thank You. I ordered the rebuild kit today so should have it by Thursday. Then the fun begins! I'll let you know the results.

 

[Lou C]

Good luck with it. You ever rebuild a carb before? If not keep in mind you have to be careful with carb cleaner. Always work in a well ventilated area (flammable) and always wear safety goggles (not just safety glasses). You do NOT want to get that stuff in your eyes. The cleaning is the most important part. You will need compressed air to clean out jets and passages.

 

[smassey22180]

You may not want to put a ton of effort into that old carb. The shops by me won't even take them as cores. They have discontinued the rebuild kit so it is not easy to get a complete kit. I was able to piece one together but not all the parts were the same. Make sure the length of your secondary diaphragm rod is the same. If I were to do it again I would replace the carb with the newer version. Yours probably does not have a power valve so you can improve your fuel consumption with the newer version.

https://www.holley.com/products/fuel_systems/carburetors/marine_carburetors/parts/0-80492

 

[jrgcbg40]

I have never rebuilt a carb before.I have been watching you tube videos on the 4160. It doesn't seem to terribly difficult. I will take a lot of pictures and take notes as I go.I also ordered a book.(Holley: Carburetors, Manifolds & Fuel Injection (HP1052) Paperback ? June 1, 1994) to read up on before I start. I have a good amount of tools,large air compressor,safety equipment. With the help of these forums I've been able to accomplish lots of jobs I'd never have attempted years ago.I'm slow and methodical with a little OCD thrown in So I'd never make it on flat rate.Hardly ever made flat rate back in the day come to think about it.
I will check on the length of the secondary diaphragm rod.The cost of a new carb is out of reach right now.Maybe next year if this one continues to be problematic.
Supposedly it has been rebuilt twice from the dealership I bought it from. (My first inboard outboard so a little green.)Water tested with the dealer after the rebuild. Noticed a flat spot on acceleration, where the boat would take off then bog at around 3500 rpm then take off hard again.The dealer said wow did you fell that..that's the secondary's opening. Nice rebuild job. NOT really. After researching, I put the quick change secondary cover and went up one spring size and no more bog and it pulled like crazy. Last year 51MPH gps verified (speedo said 53) with 4 people a cooler and gear aboard. It has a Solas 4-Blade Prop Aluminum, 14 dia x 21 pitch and still over revs at 5200 rpm. The First year I bought a Solas 3-Blade 14.3 dia x 21 and it ran 48mph but would over rev a lot. I didn't go up to a 23P because I read that the 4 blade would reduce rpms 200 to 300 rpm over the same pitch 3 blade.Maybe I should try the 23P ? Ok getting waay of topic.
Thanks for all the advice and I'll let you know how it turns out!

 

[jrgcbg40]

No Title

I took some pictures of the carb and having a hard time matching up the numbers. The only one that shows up is 80487? Which if this is the carb number then the 37-119 renew kit is not correct? Its calling for a 703-66 renew kit which I cannot find? Do I need to start a new thread?
Thank You

 

[smassey22180]

Renew kit for 80487 has been discontinued. I used this and everything was right except for the secondary diaphragm.
https://www.holley.com/products/fuel_systems/carburetor_components/rebuild_kits/parts/703-29

You won't need the power valve as the 80487 does not have one. The rebuild is easy. It just will take several hours to completely remove the old paper gaskets. If you are lucky they will be the newer blue ones that come off better.

 

[jrgcbg40]

Thank You! I'll order the 703-29 kit!

 

[jrgcbg40]

No Title

While I was waiting for the correct rebuild kit to come. I decided to disassemble and clean/adjust the carb. It was relatively easy especially with the Holley Book.
The gaskets around the fuel bowls were blue and came off without ruin.The inner gaskets were black but still came off without breaking. I cleaned it all up ,adjusted the float on the primary bowl. It was too high.Then for grins I put it back together and back on the boat. I started the boat and had the same crappy running as before except no more fuel leaking from the venturi.
I then hooked up a vacuum gauge and took some readings. While it was idling around 1200 rpm it was in the green area. As I lowered the rpms the gauge reading went down into the "late ignition timing" area. I then hooked up the timing tool and checked base timing and the vacuum reading. I will attempt to attach links to videos I took of the different tests. I also will try to attach some photo's I took of the inside of the distributer,which looked nasty.
Do you think I still have a carb issue or should I look elsewhere? Could the timing chain have jumped? The rotor looked like it was pointing just past the #1 area of the distributer? If its an ignition problem where would you start checking?

You Tube Links.
https://youtu.be/pgEsh44gYHc
https://youtu.be/k61ME4jRgPs
https://youtu.be/Q9U0Cbi6_9c
https://youtu.be/VryZjQ8DUkk
https://youtu.be/xRcGsSaPWm8
https://www.youtube.com/channel/UCmyrCX2E3BKbsWC9eoumhzg



Thank You.