Expert help needed. 1992 V-150 wont idle.

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I'm hoping someone can help me out here. I bought a used very low hour 1992 Black Max (0D077862) that had low compression due to a broken oil line from the remote tank to the oil pump. The engine started and ran fine, but had no power due to the low compression.

I pulled the engine and rebuilt it with new rings, pistons, bearings and all new gaskets. There was no galling of the cylinder walls and a light hone cleaned it up just fine.

I've got the engine back together and now I'm having some trouble with starting and idling. I added 3 quarts of oil to the 38 gallon fuel tank for break-in.

Link and sync is spot on. I went through the factory service manual to a tee. .462" BTDC marking of the pionter etc etc..

I just rebuilt the carbs with all new parts. Primer bulb, all fuel lines and fuel filter are brand new.

I get a nice big fat blue spark on all cylinders.

All spark plugs look the same - slightly oily. Fresh ones don't change anything.

I've got about 5-6 gallons through it and have since checked compression. - 120 +- 2 psi on all cylinders.

Battery is brand new.

**** I can get the engine started with 1/2 to 3/4 throttle in neutral and some choke - regardless if its hot or cold. The engine has excellent throttle response from 2k to 5.5k. It just wont maintain an idle. Forget about putting it in gear, it just stalls. Yesterday I did manage to get it in gear and get it up on plane, ran great at mid to full throttle. Idle back down and it quits.

Squeezing the primer bulb has no effect. Gets hard, stays hardish.

I can get it to idle on the muffs with the idle set a 0deg. If I go to 4 deg ATDC then it loads up and quits.

Someone help, I've run out of things to check. I know I'm overlooking something simple. It runs so good up top...now if I can just get it to idle as good as it did before the rebuild....

 

[j_martin]

Re: Expert help needed. 1992 V-150 wont idle.

Did you use the right diagram to run the bleed lines? It's different between horizontal and vertical reeds.

I'm assuming you checked out the reeds when you had it torn down.

John

 

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Re: Expert help needed. 1992 V-150 wont idle.

I've got the factory service manual for my engine. It only shows horizontal reeds. I suppose I could have a bleed hose routed wrong. I haven't checked that since I re-assembled the engine. Reeds checked out fine. I couldn't get a .005" feeler gauge under any of the reed pedals.

The funny thing is it seems load makes it worse. I can -eventually- get it to idle on muffs at 0 deg, but in the water...nothing below 1500 rpm.

 

[Unbalanced]

Re: Expert help needed. 1992 V-150 wont idle.

j-m, what is the function of the bleed circuit?

 

[j_martin]

Re: Expert help needed. 1992 V-150 wont idle.

j-m, what is the function of the bleed circuit?

Excess fuel pools up behind the reeds. The bleed system pulls it off and feeds it to the cylinder opposite it in timing. 1-4, 2-5, etc. There is a check valve in each hose which is easily tested with a syringe.

The upper starboard fitting would be #1 in a vertical reed engine, #2 in a horizontal reed engine.

If there is any air intrusion into the intake system, it will affect idle. Faulty bleed valves, or misrouted bleed lines is just one such fault.

Exhaust troubles, such as insufficient relief can affect idle in the water.

It should idle with the timing a lot later than 0 degrees. Something is drastically wrong, either in air intrusion, or in carb setup.

hope it helps
John

 

[Unbalanced]

Re: Expert help needed. 1992 V-150 wont idle.

Thanks for the responses, j-martin!

I'm pulling my hair out here trying to figure this one out. At this point, as soon as daylight hits, I'm re-checking the air bleed circuit and checking the check valves. Something clogged with slurry from de-glazing the cylinders?

There was no change from before the carb re-build to after. I'm very attentive to gasket mating surfaces and proper torque settings. I've used all new Quicksliver gaskets.

Is there anything else I could have missed or assembled incorrectly to cause this? A bad ground somewhere? What does the tilt (mercury) switch do?

I did notice something today that may spark something in someones mind. I was checking the idol timing and all of sudden I didn't see any timing marks. It was flashing on a different part of the flywheel. I checked to make sure I had the #1 instead of #2 plug wire and by the time I re-checked the timing, it was back to normal. Maybe I was picking up spark from #2 since the inductive lead was laying next to the #2 plug wire??

 

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Re: Expert help needed. 1992 V-150 wont idle.

I checked the bleed system routing and functionality of the check valves. All checked good. I was able to suck a little fuel from a couple of the bleed lines when using a small syringe to verify the check valves. I assume this is normal.

I also checked the stator, trigger, coils and wiring. I don't have a DVA meter - only a Fluke 71 so I didn't check the switchboxes.

Is it possible the crank rings are leaking bad enough to cause this? They weren't galled up I could spin the crank freely when I put the block halves together.

I'm completely stumped... Anyone have any other ideas?

Bad gas???

 

[j_martin]

Re: Expert help needed. 1992 V-150 wont idle.

The mercury switch shorts the kill circuit to ground. It can be disconnected. While yer at it, disconnect the kill wires from both switchboxes and check between the wire and ground with the ignition switch on. It should be open. It shorts to ground with ignition or kill switch off.

Is there a chance you either put the wrong pistons in, or put them in wrong?

The logic is, The engine is simple in theory, and in actual operation, but the design (port timing, port holes in piston, etc) is pretty tricky, and also highly variable between engine designs. If you have compression, fuel, and spark, it should go per specification. If it's assembled wrong, you might have good looking numbers, like compression, and it barely runs. Turns out wrong pistons or installed backwards.

It's been seen before.

On the variable spark, try another flywheel if you have one. Long shot, but easy experiment.

Just thought of something. Seems to me someone here had trouble like this, and it turned out a flywheel he bought was an inline flywheel. The wrong parts thought comes up because if an engine has enough compression to start, it ususally will run quite reasonably, except maybe at idle. If it had real poor high speed performance before you overhauled it, it might have had wrong parts.

hope it helps
John

 

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Re: Expert help needed. 1992 V-150 wont idle.

The engine had never been wrenched on. There were no marks on any of the painted bolts.

The pistons matched up and are installed correctly. All the S's are on the starboard and on the P's are on the port side with all the UP's at the top. I did match the pistons to the OEM's as the replacement are aftermarket.

The merc switch tested fine.

I removed the idle stabilizer with no change.

I don't have variable spark, I think my timing light was picking up plug #2...

I just started and ran it on the muffs out in the driveway. I can get it started and it will stay running at 1500 RPM or so. Instantainious throttle response. If I pull it down to idle, it will idle for 10-15 seconds the start to pop and eventually quit.

*** I noticed my volt gauge reads right at 12v and will <slighly> climb with the RPM's at 2k or more, at idle, the volts drop below 12v. This is with the voltage regulator disconnected. Could this be a recifier problem????

 

[j_martin]

Re: Expert help needed. 1992 V-150 wont idle.

The symptoms you describe are fuel starvation.

Did you put in a fuel pump kit?

Did you replace the fuel pump pulse line with tygon?

Voltage sounds normal, with slight variance in meter. Besides, there's nothing in the charging circuit related to engine ignition.

John

 

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Re: Expert help needed. 1992 V-150 wont idle.

Hey John, you may me on to something...

I just put the motor in a tub and on the muffs, and started it up. When It started to die, I sprayed some fuel in the airbox and the RPM's picked up...

Funny thing as I ordered a fuel pump kit when I picked up the carb kits as the fuel pump kit was out of stock.

I thought if the fuel pump were an issue (there isn't any fuel in my pulse line) that it would show up at high rpm or I would be able to squeeze the bulb and have that make a difference if the pump were bad. :redface:

 

[j_martin]

Re: Expert help needed. 1992 V-150 wont idle.

Normally, squeezing the primer bulb will compensate for a failing fuel pump.

You have proven, however, that it is a fuel problem at low speed.

Fuel pump can be proven with a pressure gauge. Just replace the plug on the last (usually bottom port) carb fitting with a hose barb, and hook up a 10 - 15 psi gauge to it. (canner kettle gauge in a pinch) Pressure under all conditions should exceed 2 lbs and be less than 8.

I have seen the thumb sized filter get plugged up intermittently with a nearly invisible goo from decomposing stratified fuel.

Keep diggin'. It can't be that complicated.
John

 

[j_martin]

Re: Expert help needed. 1992 V-150 wont idle.

Nasty thought just occurred to me. Could you have a bit of water in your fuel?

Pressures, squeeze bulb, etc. are all normal, but water doesn't burn.

 

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Re: Expert help needed. 1992 V-150 wont idle.

The fuel filter is new, as is the entire fuel system sans fuel pump.

There's no water in the fuel. I've run off a remote tank with fresh fuel with no difference.

I'll see if I can round up a low pressure gauge, but I can have a new pump kit on Tuesday and it's due for a replacement anyway since I have no idea when it was last replaced.

I pulled it appart and check it out. The diaphram looks stretched out but not torn or dirty.

I'll report back on Tuesday unless anyone has anything else to check or some other trouble shooting ideas.

 

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Re: Expert help needed. 1992 V-150 wont idle.

Well folks, the problem turned out to be a broken crank sealing ring. I guess I broke it during assembly and didn't know it. I figured it had to be something I did since the engine ran well before the teardown except for the low compression.

:redface:

Jeff