OUTLAW EAGLE MANUFACTURING

rustyzipper · Joined: 08 Oct 2009 Posts: 67

New to the SJ engine and am trying to figure out a rich condition on this engine. top two cylinders running rich and fouling plugs after last owner "Fogged" engine. Engine runs fine on trailer but smokes heavily. push it off the trailer and mak a few runs and the thing fouls top two plugs...on the EFI is the oil premixed then injected or is oil on the drip in 3 different areas on the intake...also how many fuel injectors is this engine running. how long should this take to clean up "Fogged" engine? total run time so far after Fog job is approximately 15 min idle and 5-10 mins tops of WOT at about 20 second bursts....any input appreciated....

ntjetboater · Posted: Tue Sep 14, 2010 11:59 am Post subject:

I am not a big fan of fogging and fuel stabil..i have found they both create issues like you have mentioned.
I would check the following...
compression
fuel filter check and change(both)
oil filter

Not sue on where exactly the motor puts the oil, but it does pressurize it to 3psi I think. ONly use top quality oil..SJ's do not work well with cheap oil.
I believe there are 6 injectors one for each cyl.

There are some SJ gurus on here that will chime in...I too am a SJ rookie.
good luck

rustyzipper · Joined: 08 Oct 2009 Posts: 67

changed all the filters already and only using the mercury injector oil. motor runs fine for a bit (1 minute) at WOT after changing fouled plugs. then starts missing. guess I will just keep repeating the process until I go broke from buying plugs. I know the motor is good because it ran great before the "Fogging" BS....Also is there a way to block off the oil injection and just premix?

Alumaman · Joined: 26 Jul 2005 Posts: 306 Location: Whitecourt

No mechanic here but I have been learning a bit more about these over the summer.
Fuel supply begins with an electric fuel pump (you hear it running when first turn key on, and runs only for start ups and to prime the mechanical pulse style diaphragm pump). Raw fuel is inlet controlled at the vapour separator by a float and needle valve. In the vapour separator it is mixed with the injection oil. The ECM controls the mix ratio from 40 ppm at idle to 125 ppm wide open. Mixed fuel is then picked up by a high pressure pump (its inside the vapour separator) and delivered to the fuel rail. There are six injectors on the fuel rail. The injectors receive signals from the EFI Electronic Control Module (ECM). The pulse width will widen or narrow depending on a bunch of signals received from sensors. The ECM also receives a signal from the crank position sensor to fire each injector and coil accordingly.

The 240 has a firing order of 1,2,3,4,5,6, but it actually fires two cylinders at once. 1,2 then 3,4 then 5,6. That's why they sound like F1 cars at idle. Also explains why you are seeing both the top two cylinders foul.
Unlikely to be an ignition coil as why would 2 fail? Not likely the oil mix as all injectors are fed from same system. If no spark, should be wet plugs not fouled.
So.... my guess is an injector stuck open, or the ECM is causing the grief.
Is there a Mercury shop close by, as it might help to hook it up to a Diagnostic Terminal (DDT).

Arthur · Posted: Tue Sep 14, 2010 2:54 pm Post subject:

I love my SBC....just sayin'! Wink

rustyzipper · Joined: 08 Oct 2009 Posts: 67

well I got to put some serious time into it yesterday...running good now....checked the plug wires , coils , compression, all good. the shop that fogged the engine had premix fuel in tank as well. got gas in tank cleaned out to straight fuel and changed the plugs a couple of times and the thing runs strong now with just a slight hint of smoke...damn for the first hour it looked like the BP horizon on the river bar. LOL. Guess we just had to burn the oil out of the thing and get all holes firing...oil injection block off kits outs there? or is the stock system ok(bullet proof)?

blen · Joined: 31 Oct 2006 Posts: 53 Location: Vancouver

I think it is hard to block off the Oil inj on the 240 because the ECU would need to be reprogrammed to not put the engine in Limp mode when the sensor fails to see inj oil. I think the the inj system on the 240 is reliable and have not heard of any engine failures related to it. The 240 uses a elec oil pump unlike the crank gear driven ones used on the 175.There has been alot of failures on the 175s because the plastic gear on the crank tends to strip. I have run the 175 and the 240 and the 240 runs alot colder than the 175 I have heard that the plugs foul alot easier on a 240 then a 175 because of this. A really good resource for Merc 2.5 L motors is a web site called ScreamandFly.