39082 Fuel Pump

[engrkenr]

To answer this Merc #39082 fuel pump Q will likely require someone with vast knowledge and experience. No dealer or any parts retailer or the commonly available repair manuals can answer my issue, not even Merc in Fon du Lac could! There is an error in the info Merc has made available to the field for these old applications for the 39082 fuel pump. Here is the same #39082 fuel pump first listed first for my application (1968) and the second for another Merc motor (1970). Note the difference in orientation of the pump...the check valve(s) are right in both but, not the pump body. One of them has to be wrong! I find it inconceivable that it makes no diff because the vent hole for the pulsating diaphragm is upstream in mine and downstream in the other. Which is correct? Secondly, how do you R&R the check valves without destroying them?
I can't find anyone who actually knows. This is a hardship for us old Merc owners. Please see links below.

http://www.marineengine.com/parts/mercury-outboard-parts/60/1916139-thru-2529894/fuel-pump-assembly

http://www.boats.net/parts/search/Merc/Mercury/1970/1040100/FUEL PUMP ASSEMBLY (39)/parts.html

 

[Fun Times]

Hi there, what engine model are you working with? Serial number handy too?

Looks like that part number had superseded roughly 4 times over the years. Plus maybe a conversion kit number 33852A3 too?

NEW OLD STOCK MERCURY QUICKSILVER FUEL PUMP ASSY 39082A5 ,CROSS MATCH : 33852A3 , 184571. THIS PART IS OBSOLETE.(PAPERWORK SAYS MERC 60 FUEL PUMP CONVERSION 33852A3).PLEASE BE SURE THIS WILL FIT YOUR APPLICATION PRIOR TO PURCHASE.OBTAINED FROM A LOCAL MARINE DEALERSHIP CLOSEOUT AUCTION.
https://www.ebay.com/itm/MERCURY-QUI...9Z7mbI&vxp=mtr

39082,https://www.ebay.com/sch/i.html?_odk...39082&_sacat=0

39082A2,

39082A4, https://www.ebay.com/sch/i.html?_fro...082a4&_sacat=0

39082A5, https://www.ebay.com/sch/i.html?_odk...082a5&_sacat=0

https://www.ebay.com/itm/NOS-MERCURY...-/111819693441

 

[engrkenr]

Fun Times, Yes, I saw those very items you provided looking decipher what was wrong between the Merc exploded view diagrams and the available parts. Take for example the item you sent, namely, https://www.ebay.com/itm/NOS-MERCURY-MARINE-39082-FUEL-PUMP-ASSY-39082A-4-/111819693441 If you were to install that very 39082 pump per Merc's instructions for my 1968 Model 60 SN 2287109, the check valves will be pointed backwards and not a drop of fuel will get to the carb. So, this problem is far deeper into engineering than meets the eye. Merc has apparently released the exact same part number with check valves installed in 2 different directions and created conflicting assembly drawings and the service world just has to figure it out and we mechanically inclined customers just have to hope for the best. Fon du Lac seems to have washed their hands of it..."too old". In summary, to make the part you referenced above which is just like my pump, the check valves have to be knocked out and reinstalled pointed in the opposite direction to work, but, that part will work fine in the 1970 because Merc simply reversed the pump in the assembly drawing thereby pointing the check valves in the correct direction. This is abysmally bad engineering practice. Fon du Lac should tell us definitively that as long as the check valves are pointed toward the carb, the pump's orientation doesn't matter but, because of the relief hole, I don't believe it.

 

[racerone]

I believe that these pumps are very simple and it should be easy to figure out which way the fuel flows.----It should be easy to see how the diaphragm is operated by + pressure pulses and slight negative pulses.-----It should then be easy to see which way the check valves go.

 

[Fun Times]

While your links above in the first post are dead links due to website competition, etc. which aren't permitted here, it looks like you meant to send the same type of info in the two following link found in the earliest 60 HP engine model parts catalog,
FUEL PUMP ASSEMBLY (SERIAL NO. 1552144 AND BELOW)
FUEL PUMP ASSEMBLY (SERIAL NO. 1582403 AND ABOVE)

Just for reference as it's not mentioned yet; '33852A 1 seems to be first part number used, https://www.ebay.com/itm/FUEL-PUMP-...ash=item466bd4464a:g:v~sAAOSw5ShZvws3&vxp=mtr

The check valve number also seemed to supersede around a bit such as 21-22974A2 , 21-22974A3 21-22974A4, 21-22974A1, 21-22974.

^ With that I believe you missed a crucial message from racerone in your last (other) topic regarding the check valve, http://forums.iboats.com/forum/engi...ercury-mariner-outboards/10502967-check-valve

???----All these pumps use 2 check valves !!----One lets fuel into the pump and closes so fuel does not go back to the tank.----One opens to let fuel go to the carburetor and closes so that fuel does not come back to the pump.

Knowing that, be sure to keep an eye on the check valve quantity used between the years/serial number ranges as some seem to list one while others show two used....That may be why you are seeing 2 valves when looking up your part number under your serial number range while others seem to use/sell one.

If you end up having to take out or switch directions with damage done to the check valves; 'though pricey, new valves are still available searching the part number(s) online such as EBay.

 

[tommarvin]

You could put it back together and see if it pumps fuel, if not try the other way, ?

 

[engrkenr]

All this input is good for the community and yes, each 39082 pump requires 2 check valves despite the fact that every single Mercury exploded view drawing I have seen show only one check valve on the carb side of the pump pointed toward the carb. I have not seen one Mercury drawing showing the second check valve on the upstream side of the pump chamber where it belongs. All that is needed now to really help the community and bring this one home is for some smart guy to tell us all how to R&R the check valves because Mercury has left all us high and dry. Shame on them!

 

[racerone]

Perhaps somewhere it states -----2 required ----on the parts page ???-----Very simple pumps so do not blame someone else !----Edit-----Yes it clearly states 2 required on the parts page.-----Have a bunch of these pumps laying around in the pile.----Will have a look at how the check valve is installed / replaced !!!

 

[merc850]

Since I don't know the pump style by the part nr. here are two pages from different manuals that show fuel pumps I don't know what manual you're using but you can see every pump uses 2 valves.

 

[merc850]

What lead you to suspect the check valves?

 

[engrkenr]

Merc850, An applause is warranted. These are the first drawings I have seen which actually address the check valves which includes the detailed installation procedure. Although these were written for the Mark 6 pump, the procedure for the pump in my 1968 6Hp Model 60 is likely very similar. (How do I print the docs?)

The reason I focused on the check valves is because I have done everything else to find out why I can't get the motor to give me WOT power. I have spark at the plugs and to the plugs; I have compression in both cylinders; I rebuilt and recalibrated the float , changed the fuel filter, cleaned the carb and checked all orifices for blockage; new gaskets everywhere; replaced the fuel line; replaced the vac line to the f/pump; rebuilt the pump except for the check valves. I am stumped...so, I want to change the check valves and couldn't find how to do it and in that investigation, I saw that the same 39082 pump is used in 2 different directions between 1968 and 1970. In case new check valves don't do it for me, anyone got any ideas what's really wrong?

 

[racerone]

Sounds like it is running on one cylinder.-----Does spark jump a gap of 1/4" or more , yes or no ?----Or run the motor and pull one plug wire off at a time and report what happens.----How does it run when you operate the manual pump as a test ?

 

[merc850]

To save the images right click with mouse and choose save image. The procedure is from the 1965 and prior Mercury manual. I would check the fuel pump first by undoing the outlet hose and with the plugs removed pull the motor over a few times and watch for fuel, if it comes out it should be OK; you can also blow into the outlet line and there should be resistance. If you suck on the inlet side there should be resistance also. Your problem could also be improper throttle pickup and/or max. spark advance.

 

[engrkenr]

I was able to save the docs, thank you. I did a fuel flow test previously and it performed as good or better than criteria. Then I put the fuel pump in per the 1968 drawing and the squeeze bulb was instantly hard and not a drop of fuel got past the check valves to the carb which were backwards. I will redo spark test and plug wire disconnect test as soon as soon as it warms up....we're in a deep freeze here. Will advise.

 

[engrkenr]

Merc850, you appear to be right again. I ran it at about 1K rpm and pulled the top plug wire, nothing happened. I reinstalled top plug wire and pulled lower, it stalled instantly. I repeated process, same result. Then, I switched the spark plugs. I repeated the process and got the same results which means that it appears to be running only on the lower cylinder. This would indicate that the root cause is either the top plug wire, the top cylinder coil, or its condenser. I doubt I could be lucky enough to merely have something loose. Is there a set of recommended or suggested next steps to pinpoint the exact cause?

 

[racerone]

?----From post # 12-------Motor not performing ?-------It is common for a novice to blame the carburetor / fuel pump when the problem is usually something else.