Left Bank weak spark

[Dzrtrat1111]

My car felt down on power this weekend and could smell fuel in the exhaust. LS3 376/525 with Mefi 4b and CMB harness.
 

Took a temp gun to the primary tubes and the left bank (cyl 2,4,6,8) were only in the 200 ish deg range while right bank were 700 ish deg. Pulled the plugs and found that the left bank plugs looks fouled and right looked normal. I replaced the bad plugs and checked the coils and injector harness connections with no change in the way it was running. 
 

A little background, I just finished a full tear down to paint the chassis because it was still raw chromoly and was tired of fighting to keep the rust to a minimum. I painted everything with Steel-It. 
 

Could a poor ground connection cause just one bank to run like crap or am I looking for a bigger problem?

 

[Bobalos]

Fwiw, My fist goto would be fuel.  

Fuel rail, crossover tube, fitting, hose, return line.... 

 

[Dzrtrat1111]

Fwiw, My fist goto would be fuel.  

Fuel rail, crossover tube, fitting, hose, return line.... 

it’s definitely getting fuel to the left bank

 

[Mike E]

I believe each bank of coils has it's own ground. Check and clean those as a starting point

 

[L.R.S.]

Best bet is to get it to CBM and have them figure it out. Could be simple, could be complex. I hate electrical issues.

 

[Markcsand]

Mefi coils are hot always when key is on, ground triggered, definitely check te ecu grounds

 

[Travelah]

Check voltage with a multimeter between pins A and D (outer pins) on one of the coils on the bad side with ignition key on. Should be 12V.

 

[Kraut_n_Rice]

Even with a questionable ground, without a load, those pins would likely read battery voltage on a meter.  

 

[Rockwood]

Even with a questionable ground, without a load, those pins would likely read battery voltage on a meter.  

Assuming it's not obvious, yeah.  With the whole bank being dead, probably something simple.

Should see it drop significantly when cranking if it's an intermittent issue.  

 

[lincster]

There is 1 connector to run all coils per bank.

I would check that connector to make sure all pins are in the correct location.

I think it is a ground issue.

 

[Dzrtrat1111]

Fwiw, My fist goto would be fuel.  

Fuel rail, crossover tube, fitting, hose, return line.... 

UPDATE

@Bobalos you were right and I was wrong. I thought I was getting fuel to the left bank but after chasing grounds, I pulled the fuel rail and injectors. Well… 3 out of the 4 injectors were pretty clogged. I decided to buy an eBay injector test/cleaning machine which did a great job. Then I opted to buy some aftermarket fuel rails and tossed the factory fuel rail. Runs like a champ now!