At what engine speed should the trigger voltage be tested at on a 1986 mercury classi

[oldman570]

Re: At what engine speed should the trigger voltage be tested at on a 1986 mercury cl

On most carbs the float should be equal distantance from the float to the upper carb body with the carb upside down and the needle an seat installed. If fuel is comming out of the carb when priming the motor then the float is set to high, or needs to be replaced as it could be saturated, or the neddle and seat are bad and not shutting the fuel off . It is always best to replace them if they have not been done so lately.
JMO
Oldman570

 

[CharlieB]

Re: At what engine speed should the trigger voltage be tested at on a 1986 mercury cl

I think oldman is trying to tell you is that with the carb upside down and the float bowl seat level, adjust the float so it is also level. This leaves a small space between the float and the carb, a neat straight gap, nice and parallel.

 

[Coltrickle]

Re: At what engine speed should the trigger voltage be tested at on a 1986 mercury cl

Ok gentlemen, I found that I had my floats set incorrectly. The motor would scream as Long as I kept pumping the bulb however I removed the carbs again and set the floats parrellel with the carb body as described. Now when I take off I can hammer all the way down and it revs hard and launches then Boggs and Gradually gets faster but is still not opening up all the way.. Seems like the carbs are running out of fuel..

I removed my inline fuel filter and that helped a great deal however I found that I was sucking air through a crack in the neck of he pickup tube near the top of the tank.. I have replaced the tank.. That issue is fixed..

I am at a loss of ideas on this one. I wonder if I may have my vaccuum fuel pumps on the side of the carbs installed incorrectly or something to that nature.. I run 3/8 fuel line from my tank to the t in my motor where it splits to each carb. Then 3/8 from there to the carbs.. However the nipple on my carbs is a 1/4 or 5/16... Could this affect it.. It's not leaking fuel and I have a hose clamp securing it..

The reason I use 3/8 is because all of the tank fittings I have found have 3/8 nipples..

As always gentlemen I appreciate all and any input.. You guys have no idea what you have taught me!!!

 

[CharlieB]

Re: At what engine speed should the trigger voltage be tested at on a 1986 mercury cl

Do you have a FACTORY service manual for your motor?

Try this thread to see if yours is still available

Do you need any mercury manuals on pdf format!!! - Page 1 - 309079

Parts views are sometimes very helpful also, I like Merc Parts, Search with pictures

The #1 web site for genuine Mercury Mercruiser engines, parts and propellers

In-line filters, especially the screw together glass ones, can be too restrictive, a spin-on water separating filter is good.

Total length of fuel line can get excessive and contribute to low flow from excessive line loss, this is the major reason for using large hose instead of 1/4.

Have you rebuilt the carbs and fuel pump with complete kits or just taken everything apart, cleaned and reassembled?

 

[Coltrickle]

Re: At what engine speed should the trigger voltage be tested at on a 1986 mercury cl

I rebuilt the fuel pumps a few months back when my grandfather had the boat.. However the carbs fuel pumps were already disassembled and he just brought over the pump rebuild kits.. I assembled the pumps by placing the pieces where they fit.. It's pretty much idiot proof the way the alignment holes are in the parts.. Or so I thought... However at one point I had two parts that looked just alike but seemed to be made of different materials.. A shadetree boat mech. Down the road said to place them both in there where they line up on top of one another.. So I did. This may be correct but In The past I know I have rebuilt carbs on atvs and motorcycles and often times carb kits have extra parts in them for a similar but different model and all parts are not used.. I was wondering if this may be the case here??

As for the rest of the carbs I only disassembled cleaned and put back together.. I did replace the float needle also.. But no jets, floats, or anything else!!

I do not have a manual for the motor.. I will try the link ASAP but for now I am operating on a mobile phone so the PDF will not load on here.. Thanks again!

 

[CharlieB]

Re: At what engine speed should the trigger voltage be tested at on a 1986 mercury cl

I rebuilt the fuel pumps a few months back ............................................ at one point I had two parts that looked just alike but seemed to be made of different materials.. A shadetree boat mech. Down the road said to place them both in there where they line up on top of one another.. So I did. This may be correct ....................
I do not have a manual for the motor.. I will try the link ASAP but for now I am operating on a mobile phone so the PDF will not load on here.. Thanks again!

A close look at the parts list for your model and serial may reveal exactly which gaskets, diaphragm, go into your fuel pump.

The double layer may be the restriction you are looking for.

 

[Coltrickle]

Re: At what engine speed should the trigger voltage be tested at on a 1986 mercury cl

Ok guys. I have tried everything except full carb rebuilds.. The engine just can not keep enough fuel going to it at higher throttle positions.. It starts and runs fine.. But when I hammer down it will drop act like its shot out of a cannon for about 20 feet then it drops rpms and slowly builds to about 4000.. Then it will jump up to 5200 or so for about 5 seconds.. After that it slow down to barely creating a wake.. If I pump the bulb by hand it will stay around 42-4300 but never peak out until I let it alone then over 5000 for a few seconds and back to a crawl!!! If I pull the throttle back to idle and wait about 10 seconds I can hammer down and start the process all over again!!

So my questions are why does it not hit a full wot until just before the bowls are low of fuel and why cant my carbs provide the fuel my engine needs to peak perform..

It starts and idles fine, it performs rough until 3/4 throttle and will not achieve wot..

As always thanks for any advice!!!

 

[carholme]

Re: At what engine speed should the trigger voltage be tested at on a 1986 mercury cl

The correct OEM service manual for your s/n is P/N: 90-86135--5

Mercury Mariner Outboard Service Manual 1989 45 50 60 70 More Manuals Listed | eBay

In the interim, here is a condensed version of the Clymer manual which may assist you:

Small Engine Repair Reference Center Home

Download this soonest to your computer as the link is short lived.

Here is a link to the tillotson carb for the fuel pump breakdown,

http://www.crowleymarine.com/mercury-outboard/parts/275_60.cfm

Gerry

 

[CharlieB]

Re: At what engine speed should the trigger voltage be tested at on a 1986 mercury cl

How old are all the fuel hoses? Some hoses deteriorate inside, some even peel a 'flap' loose that can fold over and severely restrict fuel flow.

Quick disconnect fuel fitting to the motor can have a faulty O-ring seal, while pressurized by the primer bulb it seal fine, but once placed under vacuum by the fuel pum fails and allows air to suck in, then the fuel pump is not able to supply the carbs.

Replace all hoses to the carbs with new hose rated for alcohol laced fuel.

Test for air sucking in by TEMPORARILY installing a clear plastic hose immediately after the fuel pump, run the motor and see if any air bubbles are passing thru. Just be SURE tp remove that clear hose once finished with repairs, it is NOT fuel rated and should never be left on your motor except for short term testing.

 

[Coltrickle]

Re: At what engine speed should the trigger voltage be tested at on a 1986 mercury cl

All of my fuel lines are new.. I removed the connection at the motor and have a one piece hose from the tank to the carbs.. Of course with the primer bulb!!

I can't use the clear fuel hose trick on my fuel pumps because they are vacuum operated on the carb itself.. The only piece between the primer bulb and the carb is where my fuel line splits to each carb.. I have ordered 2 complete carb rebuild kits but do not think that is going to correct the problem.. I have even purchased a new tank...

 

[CharlieB]

Re: At what engine speed should the trigger voltage be tested at on a 1986 mercury cl

Many factory service manuals were available thru links in this thread

Do you need any mercury manuals on pdf format!!! - Page 1 - 309079

Part views are available at Merc Parts, Search with pictures

The #1 web site for genuine Mercury Mercruiser engines, parts and propellers

Between the two you should be able to make sure your carbs/pump are assembled correctly with your new kits.

Occasionally we find problems with aftermarket primer bulbs, many prefer factory bulbs, they cost a bit more but the quality is there.

Double check all fuel hoses and fittings for good sealing, air sucking into the system limits fuel flow and may be most of your problem.

Also double check WOT ignition timing. You can remove the spark plugs, ground the wires, shift into Forward gear, WOT, and use a remote starter switch to trigger the starter. With a timing light on #1 you should see the WOT timing. BE CAREFUL of the spinning prop, it can take a hell of a bite out of a leg. It wouldn't hurt to remove the prop just to be sure it can't get you!

 

[carholme]

Re: At what engine speed should the trigger voltage be tested at on a 1986 mercury cl

You will not find your manual there, that link is for early 90s thru 2003.

Gerry