Evinrude 90 hp V4 choke/primer tutorial

[tomats]

I was wondering if anyone could walk me through the choke and primer system on my 81' 90 V4? model E90TLCIM. I am not trying to troubleshoot anything really just curious how the system works. I searched the forum but didn't come up with anything. Thanks in advance. Rob

What I'd like to know is: what happens when I push-to-choke the ignition with the key prior to starting? I know these engines don't have a choke flapper valve, so its my understanding that the fuel system is being primed in some way. I just don't quite get what is happening with the vacuum and fuel lines on the block. On my block I have four nipples on each side (one pair high and one pair low) I am guessing for each cylinder. On each side of the block it looks like there is one set of vacuum lines and one set of fuel lines. The vacuum lines on each side run to the primer solenoid and the 1/16" fuel lines run to the bottom of each carburetor. This is a non-VRO system. I also realize I may not have the original block on there now.

So when I push to choke with the key, is the primer solenoid just pressurizing or vacuuming the crankcase to allow the fuel pump diaphragm to work more efficiently at start up? Or is fuel actually being delivered directly somewhere in the carbs?

And are the 1/16" fuel lines just returning crankcase fuel back to the carbs or is this some type of an oiling method for the crankshaft?

Thanks!

 

[Bosunsmate]

Re: Evinrude 90 hp V4 choke/primer tutorial

The two lines form the solenoid squirt fuel into the back of each carb which leads into the area just in front of the inlet reeds.
Those other four hoses are i think scavenger hoses to pick up unburnt fuel from bearings etc and suck it into the rear bypass cases to be burnt.

 

[Bosunsmate]

Re: Evinrude 90 hp V4 choke/primer tutorial

When you push the choke in prior to starting a little bit of fuel will go in from the pressure from the primer bulb. You are best to push it in as you turn the key so the fuel pump pressurises it.
If you a having trouble starting then make sure you are getting fuel to the top and bottom cylinders before you go any further as if any carb is not providing fuel you will have either the top two or bottom too running lean.

 

[Bosunsmate]

Re: Evinrude 90 hp V4 choke/primer tutorial

I was working on one today, it had a solenoid primer, not a flapper. It was a 82, it may of being upgraded with a solenoid.
Those little valves the hoses connect to get blocked easily so if you have the carbs off at anytime its best to check them for patency

 

[emdsapmgr]

Re: Evinrude 90 hp V4 choke/primer tutorial

It's likely your model is the very early fuel primer (choke) system. I don't think your carbs are new enough for the fuel primer hose barb to be mounted at the top/back of each carb. Your early powerhead may be somewhat different, in that the fuel is injected direct into the hose barbs which are mounted on each bypass cover-at the side of the block. Other than that, it functions just the same as bosunsmate described. The system is initially pressurized when you first prime the fuel hose bulb. When you push in on the key, it opens the solenoid and the fuel (under pressure) flows through the 4 hoses, into the 4 bypass covers-providing that extra fuel charge to start a cold engine. As the engine cranks, the fuel pump continues to pressurize the system and the fuel will flow through the hoses-as long as you push in on the key. The only pulse/vacuum line is the one from the fuel pump to the side of the block, usually the bottom cyl. The alternating crankcase suction/compression is what moves the fuel pump internal bladder.The small fuel hoses are all pressure hoses.