8HP Won't Start

[regulator23]

I have a 1999 8HP Sailmaster and can't get it to run at all. I pulled the flywheel to make sure the key wasn't sheared off. I looked for points, but didn't see any under there. I took the carb apart and it is super clean. The motor has never been used much, but it's been sitting for a long time. Both plugs have a good strong blue spark. I don't have a compression tester, but it seems to have decent compression. After trying to start with the choke on, when I turn the choke off, I have gotten a few loud backfires. Seems like that might be a timing issue. I don't know how to go about adjusting the timing on this motor. Any thoughts or help would be greatly appreciated.

 

[JB]

Re: 8HP Won't Start

Switch the spark plug wires back to the right cylinders, regulator. Your symptoms are classic for them being switched.

Let us know what happens, and good luck.

 

[regulator23]

Re: 8HP Won't Start

That wasn't it. Any other thoughts?

 

[JB]

Re: 8HP Won't Start

What happened?

Loud backfire from the exhaust happens only when the cylinder fires with the exhaust ports open.

I guess you are waaaaay out of time with the ignition.

 

[JB]

Re: 8HP Won't Start

^^^

 

[ENSIGN]

Re: 8HP Won't Start

The first thing you need to do is get a service manuel.

 

[bktheking]

Re: 8HP Won't Start

Carb probably isn't super clean, just looks that way. Carbs sitting for years usually have dried up fuel in them and passages get blocked. Spray some 50:1 mix into the carb and try starting it as a starting point then if it runs you need to dissassemble the carb, soak with carb cleaner, blow out with compressed air and reassemble with a new kit, there is no magic fix to servicing these motors. As well, did you pump the bulb on the gas line until it was hard?

 

[regulator23]

Re: 8HP Won't Start

Thanks for the replies. I did the carb rebuild kit yesterday. It was already very clean (like brand new). The bulb was pumped hard. I removed the fuel line from the carb and gas flows freely from the fuel pump. On the coil, in addition to the 2 spark plug wires, there are two other plug on wires. I tried reversing those as well. It won't even attempt to start. After pulling with the choke open a few times, it only backfires when the choke is off. I've tried putting fuel into the spark plug holes, I've tried spraying starter fluid into the carb, nothing seems to help. I can't see any sort of timing adjustment under the flywheel. This doesn't make sense because it has great fire and it has fuel. Help!

 

[bktheking]

Re: 8HP Won't Start

Guess if it has fuel and spark, check compression next.

 

[JB]

Re: 8HP Won't Start

Switch the spark plug wires back to the right cylinders, regulator. Your symptoms are classic for them being switched.

Let us know what happens, and good luck.

What happened?

"That wasn't it" is not an answer.

 

[regulator23]

Re: 8HP Won't Start

When I switch the plug wires, the back fire occurs on practically every pull and it may be even louder. When the plug wires are in the orignal position, the backfire only comes after I've pulled it with the choke open a few times. In addition to the plug wires, there are two additional plugs on the coil that I also switched. They didn't seem to cause anything different to happen. I'm going to get a compression tester and see if that may be the issue, although it feels like it has good compression??

Thanks for the thoughtful responses.

 

[Silvertip]

Re: 8HP Won't Start

Has anyone mucked with this motor since it was last used? If not and it ran fine before, then timing is not the issue. That doesn't change sitting in storage unless someone screwed with it. Timing is part of a link&sync procedure covered in detail in the service manual. When you pulled the plugs, what did they look like. Dry, wet, black, tan, white or?
I as others, feel the carbs are not clean. Varnish builds in stored carbs so it is the tiny passages and jets that become clogged. Unless those are cleaned that engine will not run.

 

[Vic.S]

Re: 8HP Won't Start

with a similar but somewhat older engine I am intrigued and puzzled by this one.

If the flywheel is keyed on the shaft I cannot see how the timing can be far out except for the possibility of the plug leads (or the "low tension leads) being swapped over..

If its got good sparks the ignition circuit must be Ok .

if the compression feels good it probably is!

So it must be carb problems but it wont start when fuel mix is sprayed into the intake and it wont even start when starting fluid is tried ... back to the ignition .

I have never cleaned the carb of mine and thats a 84 model! and I don't drain the carb when laid up during the winter either!

What is everyone missing ??

Have you tried new plugs ?

I'd double/treble check those plug leads and Lt leads.

Are the sparks as good as you think .. how far will they jump?

 

[bktheking]

Re: 8HP Won't Start

It may feel like good compression, you may have great compression on one cylinder and near zero on the other. It should fire plain and simple and if it won't then something is causing it not to run, broken ring perhaps, the other part could be reeds.

 

[Gary H NC]

Re: 8HP Won't Start

Compression test and test the ignition with a real spark tester.
Just because you see the spark plug having spark it could still be too weak for the motor to run.
It needs checked with a spark tester and jump at least a 7/16th gap with a bright blue zap.
I would clean the coil grounds too.

 

[regulator23]

Re: 8HP Won't Start

The compression is 60 and 65 pounds. Is this enough? I don't have a spark tester. Is that something I can pick up at an auto parts store?

 

[bktheking]

Re: 8HP Won't Start

The compression is 60 and 65 pounds. Is this enough? I don't have a spark tester. Is that something I can pick up at an auto parts store?

It should be enough compression to make it run although it isn't the greatest it should still run. Spark testers are available at almost all auto parts stores.

 

[regulator23]

Re: 8HP Won't Start

I just pulled the head off and it is a mess in there. The pistons and cylinder walls look fine, but the entire water passages were completely clogged with a white colored hard powder. It looks like someone might have run it in salt water, never flushed it, and let it sit for years. I cleaned it all up tonight and will replace gaskets, thermostat, etc. tomorrow and try again. The head gasket wasn't blown around the piston openings, but it was a mess in several other spots which I guess might cause the low compression. Thanks for the help and I'll update after I get it back together (hopefully tomorrow).

 

[bktheking]

Re: 8HP Won't Start

Plugged water jackets have nothing to do with compression readings, they are seperate from the cylinders but they should be clean to prevent overheating. Do a decarb with seafoam once it's running to try and bring the compression readings up.

 

[bktheking]

Re: 8HP Won't Start

Do you know how to check for spark without a tester?

Spark Plug out and against engine metal while someone pull starts it, watch the spark. What plugs are in it and are they gapped properly?