Engines fired up. (long)

[paulrfrancisco]

Prior to putting the batteries in my boat, I changed the spark plugs, wires, cap, rotor and fuel/water separater on both my 1990 7.4L motors... then when the batteries were installed I started them up and I find them BOTH mis-firing and popping... I confirmed the firing order and confirmed the wires go to the correct plugs and they match the numbers printed on the top of the cap. The plugs are AC Delco replacements for the OEM plug, and everything else is genuine MerCruiser. Plug gap was set to .040 according to a local boat service center.<br /><br />The confusing thing is that both engines are doing the same thing. Also, I checked the timing and strangely I cannot locate the mark. I premarked it on the balancer with chalk, and I see the 8 degree mark, and am on the # 1 cylender, the engine is idling about 600 rpms, but the mark is barely visable behind the waterpump hose... very very advanced. Last season, the motors ran reasonably well so I dont think the timing is actually wrong, but why can I not see the mark?<br /><br />Lastly, can the carburators cause the misfires and popping problem? <br /><br />Thanks<br />Paul

 

[whywhyzed]

Re: Engines fired up. (long)

The firing order is right, but could you have all the plugs one position off on the distributor cap?

 

[I/O WALDO]

Re: Engines fired up. (long)

Wrong fire order? 18436572? Triple check your install! Maybe it was wired on the cap improperly(knott following the numbers on the cap)before U re-wired it and now U R off! Can always pull #1 plug and gitter on TDC and make SURE the rotor is pointed at #1 on cap.

 

[paulrfrancisco]

Re: Engines fired up. (long)

I replaced the wires one for one and they exactly match the positions and number references on the caps.. I was careful to do one wire at a time leaving the the old wire on the old cap, and install a new wire in the same position on the new cap.. The caps were identical.

 

[whywhyzed]

Re: Engines fired up. (long)

I'd try running out of a jerry can of new gas then

 

[Don S]

Re: Engines fired up. (long)

Check the rotors. Count the notches in the metal ring. If there are only 6 notches it's for a V6, not a V8.

 

[paulrfrancisco]

Re: Engines fired up. (long)

Mmmmm... never thought of that one... Could that also throw off the timeing reference with respect to where the light is showing it? How bad would it run?

 

[paulrfrancisco]

Re: Engines fired up. (long)

Don S you are amazing.... You hit the nail right on the head the very first time.<br /><br />Thanks so much....

 

[paulrfrancisco]

Re: Engines fired up. (long)

Aaaahhhhh... Puring like a kitten with the correct rotors installed...<br /><br />This forum has been an awesome information resource for me... <br /><br />Thanks for all your help everyone...