2 black black spark plugs, 2 nice ones. What gives?

[CharlieB]

Re: 2 black black spark plugs, 2 nice ones. What gives?

Compression is way too low on the bottom two.

Possible cause, check your fuel pump pulse hose between the pump and the crankcase for the presents of gasoline from a leaking diaphragm in the pump.

That will wash out the rings and the recirc hose will pull some of the extra fuel from one cyl into another and start washing out the rings there.

You need a rebuild, at least a re-ring, and possibly a fuel pump or a pump kit

 

[ezeke]

Re: 2 black black spark plugs, 2 nice ones. What gives?

Which plug in the picture is in the hole that reads 60 PSI?

 

[Chinewalker]

Re: 2 black black spark plugs, 2 nice ones. What gives?

Low compression IS that big of a problem. Just because your buddy ran his into the ground with one hole down, doesn't mean it was a good idea. All you need is one ring to catch and grenade a piston and then your rebuildable motor has become a pile of scrap. Plus, Murphy's law dictates that it'll crap out when you can least afford it to, like when that big yacht with the drunken millionaire at the helm is bearing down on you at 30 knots...
- Scott

 

[iwombat]

Re: 2 black black spark plugs, 2 nice ones. What gives?

Chiming in with another bit of support for what's been said.

Regardless of any other problems, your motor will never run right with compression numbers like that. Pull the heads and take a look at what's going on.