Issues with evinrude v8 carburetors fuel delivery

**powerabout** · 07-04-2018, 08:06 PM

Originally Posted by alexvzx

The engine start instantly and has a very smooth idle. Out of the water get high rpms with no problem. In the water the engine works OK until you hit the gas all the way down. The engine do not pass 3000 rpm. All electrical system is new and the loose magnets that I found during restoration were glued with omc epoxi. The issue that there is no big spray at 3000 rpm and the pulse pump are pushing 5 psi. I tested an electrical pump with same results. No fuel leak and carbs and floats were inspected once again today. Thinking that the issue was fuel delivery, I installed two electrical pumps set at 5 psi and the engine do not accelerate. The carburetors stop delivering fuel immediately after the engine was accelerated. Strange behaviour. No carbs overflow in any of the test. I tested pulse pumps too and the result were the same. The only pending test is to disconnect the cut of cables from the power packs. Pistons were check once again and were installed as per manual port and starboard. At this point I do not know what else to do.

have you run it with the pack to pack loom disconnected yet

**alexvzx** · 07-04-2018, 08:10 PM

No air box, that is the only pending test that I will expect to do this Saturday.

**powerabout** · 07-05-2018, 12:01 AM

Originally Posted by alexvzx

No air box, that is the only pending test that I will expect to do this Saturday.

Also check the carb body part number top left of main body
Just something to check to ensure they are stock

**alexvzx** · 07-05-2018, 05:03 AM

Already check that and they are for an 86 3.6 gt.

**racer** · 07-05-2018, 05:25 PM

86 3.6 has 80D stock jets the 78D were in 1985 which had a different smaller carb

**alexvzx** · 07-10-2018, 12:56 PM

The power packs cables were disconnected and the issue remains the same. Any other suggestion will be considered.

**powerabout** · 07-10-2018, 07:25 PM

You will need main jets over 80 if you run it without an airbox, do you have the baffle and airbox to put on for a test?
Have you marked the flywheel to check timing on all 8?
buy a dva adapter for your multimeter and check the coil primary voltages

Did 4 cyl keep running when you tried to stop it with the pack loom unplugged where the shift loom should go?

**racer** · 07-11-2018, 06:13 AM

86 3.6 did not have a baffle in box but came with 80D mains

**powerabout** · 07-11-2018, 08:10 AM

Originally Posted by racer

86 3.6 did not have a baffle in box but came with 80D mains

So if you have no airbox, what jets?

**alexvzx** · 07-11-2018, 05:56 PM

The jets are 76d and the engine does not have the air box. The loom was disconnected and the engine do not turn off. I am planing to install higher jets but I do not find a biger ones. I will drill them, or maybe any of you can point a store that sell me a new set.

**gotboostedvr6** · 07-11-2018, 06:34 PM

Carb throats cracked?

**powerabout** · 07-11-2018, 06:59 PM

You will still need to get the diode into the loom between the packs regardless of anything else.
Its can cause issues in all rev ranges
Time for voltage check on coil primaries to see if it drops away, make sure that the pack kills wires are separated when you do this

**alexvzx** · 07-11-2018, 07:31 PM

Carbs were inspected and all 8 are in good condition with new kits.

**racer** · 07-12-2018, 06:34 AM

Get the proper jets in it first before you hurt the engine. 4 sizes below stock is enough to cause running issues. Jets should be available from any dealer, I may have some but need to check.

**powerabout** · 07-12-2018, 09:55 AM

Originally Posted by racer

Get the proper jets in it first before you hurt the engine. 4 sizes below stock is enough to cause running issues. Jets should be available from any dealer, I may have some but need to check.

Racer, without the airbox on a 3.6, how much bigger do you need?