This volvo is killing me!

[peejcj8]

Here is my previous post.

http://forums.iboats.com/showthread.php?t=230315

I Thought the pick up tube was the issue since it ran fine after I sealed the tube. Then I replaced it with a new one. I went out fishing and bam, same thing. Boat will not idle right after it is warmed up. While we were out fishing I pulled the cap and it looked tarnished along with the rotor. I buffed them out with a screwdriver (the only thing I had). The boat then ran OK at idle, not good as new but it would stay cranked. Im thinking Im really on to the problem now, all I need is a cap and rotor, we even trolled for a few hours and caught a limit of fish.

We got back to the ramp and I cranked to flush motor and the starter sounded real bad. So next day I ordered a starter, a cap and a rotor, since I was at it a set of plugs.

I installed everything, and as soon as the boat warms it runs bad at idle still. We hooked up a vaccum guage to the port on the intake, it seemed to stay at 30psi unless the motor tried to die and it would drop with the rpms. We hooked a hose directly to the fuel pump and put the hose in a can of clean fuel, still same problem. We were thinking fuel pump so we changed it, no change.

Im going to change the coil now, for no other reason than it has not been changed.

Any advice will be appreciated.

Eric

 

[bjcsc]

Re: This volvo is killing me!

Are you sure you were getting 30in? Sounds a bit high to me...

When you rebuilt the carb, what was your procedure, i.e. exactly what did you do?

What did the old plugs look like?

Don't give up! Eventually you will figure it out. My advice, and don't take this the wrong way, is to spend more time diagnosing/tracking the problem down and less time throwing money at parts...

 

[peejcj8]

Re: This volvo is killing me!

Rebuilding the carb, Its a Edlebrock carb so its real easy. I just pulled it apart and cleaned it and replaced the gaskets. The floats were close, so I left them alone at first, then when i still had problems I pulled the top off and adjusted them with no effect.

Old plugs looked like crap, alot of carbon build up.

Believe me we have spent 3 days diagnosing the thing. The carb rebuild was due to breaking a gasket when looking at it. So far the only shot in the dark is the fuel pump, but the clear filter you could see gas just trickle into the filter, with the new pump the filter stays full, but still the motor will not idle, so im real confused.

So far we have "fixed it" numerous times


Cap and rotor were dirty, Changed them

Spark plugs were dirty, changed them

Starter went bad, and is not a part of this problem, but was changed

Fuel filter, when we had it installed, would not fill with fuel, and you could fuel trickle into it. So we changed the fuel pump, and like i said the filter is now full of fuel, but the motor still will not idle.

You can set idle to 800 RPM's and it runs fine, but if you give it throttle, and then come off the throttle it will die. The second you go to throttle it dies.

 

[Don S]

Re: This volvo is killing me!

When you rebuilt the carb, did you disassemble, then soak all the parts in carb cleaner for an hour or so? Then wash off and blow all the passages out with compressed air?
Is the choke working properly?

 

[achris]

Re: This volvo is killing me!

... and blow all the passages out with compressed air?

When he says "compressed air" he means compressed air, not those farts in a tin you can buy from the electronics shop. Good for blowing the dust off a computer fan and little else! Compressed air means about 100-120 psi.

Chris.....

 

[Lakester]

Re: This volvo is killing me!

"Compressed air means about 100-120 psi."

YES!!, the good stuff!! but be sure to wear eye protection goggles... at 100+ psi the grit can fly off at Mach speeds....

regards,
lakester

 

[Robj]

Re: This volvo is killing me!

The problem seems to be running rough when the engine warms up. This sounds like it could be a fuel issue, ie choke comes off, rough idle?? Try setting your mixture, look for vacuum leaks. Another thing, is the engine running rough at idle because it has a dead hole? When the engine is running, at idle, warmed up, do a cylinder balance test. With a heavy pair of gloves and insulated pliers, pull of the plug wires one at a time and listen for a rpm change. No change in rpm with wire removed = dead hole, drop in rpm with wire removed means that the cylinder is firing.

God luck and have a great day,

Rob.

 

[JCF350]

Re: This volvo is killing me!

I installed everything, and as soon as the boat warms it runs bad at idle still. We hooked up a vaccum guage to the port on the intake, it seemed to stay at 30psi unless the motor tried to die and it would drop with the rpms.
Eric

Assuming you mean 30 "inches" of vacuum. How are you getting such a high reading? Where did you take from? Also check it with a different gauge.
No way you should get a reading like that. Normal readings at idle are around 19 inches

 

[bjcsc]

Re: This volvo is killing me!

I'm thinking along the same lines as Don S. and wondering if you soaked (I do overnight at a minimum) and blew out the carb entirely. I wonder what you mean by "cleaned it". By rebuild do you mean you replaced all gaskets, etc..? Your carbon plugs could mean you're running rich. And it could be the idle circuit in the carb, or it could also be the choke not opening fully, esp. since your problem occurs when it warms up. Have you verified the choke is operating correctly?

 

[Flukinicehole]

Re: This volvo is killing me!

I really think you have carb issues, it needs to be gone through again. Like others have said you have to really blow the passages out. This is not a 5min job.

 

[peejcj8]

Re: This volvo is killing me!

Sorry guys, the vacuum readings were around 20 PSI at 1200 RPM and dropped down to 18 at idle. Sorry for not remembering that right.

As far as the carb. I am no expert at rebuilding carbs. I do know that it made no change from before the rebuild to after the rebuild.

The carb is 3 years old, I bought it because the old holley carb would do the same thing that this one does now.

I took the carb apart, soaked the parts overnight. I do not have air so I blew the parts with carb choke cleaner to make sure they were clear. I then used my mouth to blow through the parts (probably not close to 120 psi) I then replaced all gaskets.

The choke seems to work great, when it opens up problems begin, when it opens the engine starts running rough. When itb dies, I have to hold the choke closed some to re-crank it. This is with the engine fully warmed up.

I appreciate everyone help with this, as I do need a fresh thought pattern, as nothing I have come up with has helped.

Eric

 

[Robj]

Re: This volvo is killing me!

Do the cylinder balance test that I suggested earlier. It will tell you where your problem is and then troubleshoot the problem area. By the way, your vacuum readings are not in psi, I believe they are in inches of mercury or water column.

Have a great day,

Rob.

 

[peejcj8]

Re: This volvo is killing me!

Thanks rob. I will do the test on Monday. I also have another coil that Im going to use. Im going to test the spark before and after hooking up the new coil to see if any difference.

After that Im going to suspect the carb, again.

The carb does not look hard, Im not sure why it would be such a problem. It did not have much build up or alot of trash in it..

 

[Bondo]

Re: This volvo is killing me!

The choke seems to work great, when it opens up problems begin, when it opens the engine starts running rough. When itb dies, I have to hold the choke closed some to re-crank it. This is with the engine fully warmed up.

Ayuh,.......

That says to Me that you have a Plugged Idle circuit,......
And,....
It only takes 1 little speck of Crap to plug a tiny orifice.......

 

[peejcj8]

Re: This volvo is killing me!

That makes alot of sense, clogged idle circuit. I just looked up idle circuit and I now see that it is used during idle and when I am giving it throttle I am transitioned to the main circuit which is probably not clogged.

Thanks everyone for all the suggestions

I will look at the carb again!

 

[JCF350]

Re: This volvo is killing me!

Do the cylinder balance test that I suggested earlier. It will tell you where your problem is and then troubleshoot the problem area. By the way, your vacuum readings are not in psi, I believe they are in inches of mercury or water column.

Have a great day,

Rob.

inches of Hg (mercury) if it was a water column the scale would be 0-33 feet.

A vacuum gauge is a very versatile diagnostic tool if you know how to use one. While I haven't looked any up I'm sure there are websites on the use of one (I still keep a guide in my toolbox after 35+ years of mekanicking).

 

[peejcj8]

Re: This volvo is killing me!

The carb is soaking in carb cleaner as we speak. When I rebuilt the carb last time I just blew the bottom out with carb cleaner and replced the gaskets.

I will borrow a neighbors compressor in the am and blow the cleaner out.

There is a hole in the primary that the idle screws "screws" into to restrict. Is the slit above this port something that needs to be blown out also? I take it you do not remove the jets?

 

[JCF350]

Re: This volvo is killing me!

All passages must "blown out". All jets need to be removed (because sometimes some "gook" will remain on the back side of them). Leave in all the "pressed" in tubes and such.

 

[magster65]

Re: This volvo is killing me!

When it runs like crap, figure out which cylinder isn't firing. Take the riser off that side and look into the manifold and check for anti-freeze or water. The symptoms sound like a problem I had with a boat a few years ago.

 

[flabum]

Re: This volvo is killing me!

A soggy float can cause the fuel level in the carb to be lower than required causing this problem as well. Check the weight of the float or just replace it. Be very careful setting the float height too..... Fuel level height in a carb affects idle quite a bit.