Mechanical fuel pump rebuild services

[Don Moyer]

After adding rebuilding kits and stainless sediment bowls to our online catalog in February and March, we continued looking into ways to make the mechanical fuel pump more reliable.

It quickly became apparent that the condition of the upper housings was the single most critical threat to the pump's reliability and safety. Approximately half of the old mechanical pumps we had stockpiled for rebuilding proved to have unusable upper housings due to corrosion, warping over the sediment bowl or hairline cracks around the inlet and outlet fittings. Developing a new and stronger upper housing therefore became central to our efforts in supporting the mechanical pump option.

With this background, if your mechanical fuel pump malfunctions, or when it comes time to rebuild the pump by virtue of age, we suggest the following progressive approach:

1. Disassemble your pump, and check the condition of the major housings. If they are in good condition, including a good fit between the sediment bowl and the underside of the upper housing, you should be able to rebuild your pump using one of our mechanical fuel pump rebuild kits (http://www.moyermarine.com/cgi-bin/shopper.cgi?preadd=action&key=FPMP_13_320).

2. If you discover that your upper housing is in good condition, except for a noticeable downward bow above the sediment bowl (where the bail attaches to the housing) which causes the bowl to rock back and forth when checking the fit without the rubber washer, you can most likely straighten this part of the housing using our mechanical fuel pump repair tool (http://www.moyermarine.com/cgi-bin/shopper.cgi?preadd=action&key=FPMP_14_344).

3. If you discover that your upper housing is not usable, but the rest of the pump is in good condition, you could opt to simply replace the upper housing with one of our new (improved) upper housings (http://www.moyermarine.com/cgi-bin/shopper.cgi?preadd=action&key=FPMP_12.1_356) . This would be an especially attractive choice in cases where you may have previously rebuilt your pump and subsequently discovered a leak around one of the fittings.

4. If your pump looks like the proverbial "basket case", you can opt for either a rebuilt original pump (http://www.moyermarine.com/cgi-bin/shopper.cgi?preadd=action&key=FPMP_11_323) or an MMI mechanical fuel pump (http://www.moyermarine.com/cgi-bin/shopper.cgi?preadd=action&key=FPMP_11.1_357) which incorporates a new upper housing and stainless sediment bowl.

[shemandr]

i have the mechanical fuel pump rebuild kit. the instructions show the disassembly of the pump off the engine. i don't have good access to the engine in that area and cannot see how the pump can be taken off the engine.
the rebuild seems to require access to two bolts/screws on the bottom of the pump, removal of the priming bale and removing a pin through the diaphram post.. i can't see doing this with the pump on the engine.
how can i remove the fuel pump?

[Don Moyer]

The pump is mounted with two 1/2" hex-headed bolts. The forward bolt is usually rather easy to remove, but access to the rear bolt is restricted by the sediment bowl. If you can loosen the bail and remove the bowl, the rear bolt will be a bit easier to handle. For years I've been using a cheap 1/2" socket, which I ground quite thin around the front, to squeeze past obstructions and get to the rear bolt. I use a 3/8" extension approximately 6" long, and I've always able to get the rear bolt to turn, even though it isn't always possible to get the socket on straight.

[shemandr]

thanks for the tip. i think this is going to require an access port in the 1/4 berth locker. i glad to know what i'm after before i cut up the boat!

[Bob Grenier]

I have found that if you replace the mounting bolts with Allen-head bolts it makes replacing them a lot easier as socket clearance is no longer a problem. Also because a lot of time the back bold is done by feel only.

[shemandr]

feel only is an understatement. it took about two hours of contortionism. bleeding hands and a good patch of blue air to get that rear bolt out. i like the allen type bolt idea. thanks.

[shemandr]

one question on the rebuild of the fuel pump: since the lower housing cover came off with an explosion of springs and associated parts i did not get to examine the placement of same. i surmized from the picture that the two springs are placed, one on the rocker arm and one on the end of the rocker arm over the end of the plunger/diaphram. they then fit the hubs on the cover on the other end. is that correct? assembled this way i get a healthy squirt of gas using the priming lever, and similar noise if i engage the end of the rocker arm and push it with a screwdriver.

[Don Moyer]

I would have to say that you have most likely gotten your pump back together properly.

Don

[shemandr]

the pump, the carbuerator and new racor filter are all installed and the engine runs smoothly. i don't know if the stalling problem is solved because that could happen after an hour or more of smooth running.
after installation of the filter, and before removal of the mechanical fuel pump and carbuerator for the rebuild, there was a gas odor. yes, i did spill gas cleaning the bowl to the fuel pump and cutting the fuel line for the filter. but it seemed like there was some gas in the throat of the flame arrester. i haven't decided if it still exists after the rebuilds. i am wondering: i put the fuel filter a bit higher than the fuel intake to the fuel pump to allow access to the bottom of the filter for draining. is the only safeguard keeping fuel from filling the float chamber, and hence overflowing into the air intake, the quality of the needle valve seat?
i could install a longer fuel line with a dip below the level of the fuel intake to discourage gravity flow from the filter when the engine isn't running. the fuel tank pick up is on the top of the tank and is above or level with the fuel pump intake.

[Don Moyer]

You really should have a manual fuel valve somewhere ahead of the carburetor, so that you can positively shut off the fuel to the carburetor while you're away from the boat. While it's true that a perfect float valve will keep fuel from collecting in the throat of the carburetor indefinitely, all it would take is a "fly-speck" piece of crud to hold the float valve open.

Regards,

Don

[shemandr]

that needle valve doesn't seem like enough security for my taste. one good thing about doing this myself is gaining an appreciation for issues like this. if i paid a mechanic to do this i wouldn't have given it a second thought.
there is a shut off on top of the fuel tank about six feet away. that still leaves fuel in the in the fuel line and fuel filter, which could flood the carburetor if the vacuum from the tank to the carburetor were broken. do you think i need a shutoff, say between the fuel filter and the carburetor?

[Don Moyer]

Placing a valve just ahead of the carburetor would be the most conservative approach, especially for long absences from your boat.

However, if your needle and seat has chronic problems of leaking, it would be good to know it, since a leaky float valve will lead to a rich running condition. For this reason, you may want to leave the valve just ahead of the carburetor open while you're on the boat to observe it from time to time.

[HOTFLASH]

You really should have a manual fuel valve somewhere ahead of the carburetor, so that you can positively shut off the fuel to the carburetor while you're away from the boat. While it's true that a perfect float valve will keep fuel from collecting in the throat of the carburetor indefinitely, all it would take is a "fly-speck" piece of crud to hold the float valve open.

Regards,

Don

Or is another one needed? Is there a way to regulate that valve from the cockpit without having to open the engine compartment?

[Don Moyer]

The basic concept of a manual valve sort of dictates that it would be located in the fuel line itself, and at a location that best protects the boat from a fuel leak while it (the boat) is unattended.

You could no doubt find a valve with a remote control feature to turn the fuel off and on from the cockpit during the time you're on board (an electric solenoid comes to mind), but then you'd probably still want to have a manual valve to back up the remote controlled system when the boat is unattended. I would list a manual fuel valve in the same category as a through-hull, where there's really nothing quite like "putting your hand on a valve" to give you the security you're looking for.

Best regards,

Don

[mingamells]

Currently, my fuel pressure is 5.5 psi with (apparently) the standard mechanical fuel pump. Would your rebuild kit reduce the fuel pressure to typical levels (3-4 psi)?

Thanks in advance.

[Don Moyer]

Yes, but unless you're experiencing problems (flooding of the intake throat of the carburetor etc.) 5.5 psi doesn't usually present a problem.

Don

[HOTFLASH]

Anyone know a source for Allen head bolts to attach the mechanical fuel pump to the engine?

[Bob Grenier]

Any good Auto parts center or Home center will have what you need...Just bring your old bolt and match the thred and size.

[Dana Paterson]

I just removed the Mechanical Fuel Pump from my Atomic 4 this last weekend and replaced it with a blanking plate. Not knowing that it was supposed to be very hard, I approached it from the flywheel side. To put light on the subject, I positioned myself in front of the flywheel and shined a powerfull flashlight through the slot between the spark arestor and the valve cover. This illuminated the front bolt quite nicely. I then reached around the carb with a 3/8" drive equipped with a 3" extension and a 1/2" socket. First bolt off...no problem. I then removed the extension from the drive leaving the socket on the extention and probed for the rear bolt until I found it. Leaving the extended socket on the bolt, I reached back and clicked the drive onto the extension and backed the second bolt out. Again...no problem.

What i want to know, Don, is should I have left the push rod in place when I put the blanking plate on? I saw no reason to do so and removed it and put the blanking plate and new gasket (with sealer) on. Now, I'm thinking about the little hollow spot machined into the pushrod side of the plate and hoping that I haven't done something really stupid. a quick answer would be appreciated.

Where would I be without this site! Thanks.

[Don Moyer]

Dana,

Congratulations on performing a very difficult task with apparent class and dignity which many of would have felt the need to resort to a bit of "colorful" language before finishing. You were correct to leave out the little pushrod. In fact, if you had left the rod in place, it would have pushed out through the thin layer of metal at the end of the recessed area
in the cover plate.

Don

[marthur]

That colorful language I prefer to call the "magic words" because it has helps me through the most difficult part of the job ; )

[keithems]

removed my mechanical fuel pump last nite -- not very hard -- used a 3/8 drive with a 14 mm socket [it's all i had -- but maybe it had just enuf flex to grab the bolt without stripping it?] -- and most importantly -- a 1" extension called a "wobbly" -- one of my favs for when i can't grab a bolt head directly -- also, to be fair -- my c&c 30 has lots of working room -- esp. since i'm rehabbing and removed the plywood sheathing around the engine compartment -- frankly, i may well leave it off, since i always want to be able to get at my engine easily -- and when you hide the engine, u neglect it and they get that pathetic rust covered look [as opposed to the glamorous rustoleum red look mine has :) ]

ok -- now my question -- i thought my fuel pump was shot cuz the primer didn't move and the line was totally dry -- but once i had it off, the primer moved and pumped fuel out of the tank for me -- so i reinstalled it -- and -- once again, the lever won't move, though i think the fuel is flowing -- motor had run fine, then a few days ago, just quit 5 sec. after start up -- ever since -- nothing -- i also installed a groco 376 fuel filter last nite [says filters down to 3 microns] and pulled the carb and fuel pump drains -- the fuel doesn't look that bad -- so i'm wondering -- seeing as no coughing, misfiring, etc. -- is it really an ignition problem? -- i had loosened the distributor on that last startup [i know, i know -- should have done that after start, not before] but since then i've reset the timing to tdc and tightened it back down....

[rigspelt]

ok -- now my question -- i thought my fuel pump was shot cuz the primer didn't move and the line was totally dry -- but once i had it off, the primer moved and pumped fuel out of the tank for me -- so i reinstalled it -- and -- once again, the lever won't move, though i think the fuel is flowing (snipped)
If you are referring to the manual pumping bail on the mechanical fuel pump: mine would not move when I gingerly tried it before the mechanic arrived to give my "new" old A4 a good inspection after buying the boat. He said it was because of where the crankshaft had stopped. We turned the shaft a bit and it pumped fine. Does that describe your situation?

UPDATE: I later discovered this INvaluable tidbit by Don Moyer: http://www.moyermarine.com/forums/showthread.php?t=827

[ryanmohr]

I too had an explosion of springs and parts when I opened up my pump. I ended up losing one of the spring caps under the engine and can't get to it.

Everything else on the pump is in decent condition so I don't need a full kit. Where can I purchase the little spring caps? Is it possible to pick up a replacement at a local hardware or auto supply store?

[jerrysingle]

A few months back I was engaged in the exercise of rebuilding a fuel pump which led to buying a rebuilt fuel pump which led to a leak in the sediment bowl and ordering gasket and stainless bale.

Now I cannot stop leaking from the sediment bowl. The gasket that came with the rebuilt fuel pump leaked almost immediately. Tightening broke the bale threading connection so we ordered the bale and gasket The gasket appears a quarter inch smaller in diameter than the replacement and very hard.

Now installing the new bale and new gasket ... the sediment bowl is still leaking.

Any thoughts?

[ndutton]

Please forgive the wise-a$$ answer but yeah, I've got a thought. Why not drop $40 on an electric pump and be done with it?

[hanleyclifford]

In his own inimitable way Neil makes a very good point. Most of the active members on this forum it would seem have gone the electric route. Mechanical pumps are increasingly expensive to buy or rebuild. The sediment bowl arrangement no longer seems adequate in the age of ethanol. Most of us have resorted to some type of cartridge filter/separator which can be mounted at a place convenient for observation and service. Such units can handle a lot of crud and water. Electric pumps can also be mounted remotely and conveniently: this is a big consideration for those with difficult engine access. Finally, electric pumps eliminate the danger of the dreaded ruptured diaphragm. The Facet and Carter units are the ones we hear most about.

[ndutton]

Apologize again for the crack, I was in a wisenheimer mood.

The reality is we will all eventually go electric if for no other reason than attrition and corresponding lack of parts availability. With regard to the mechanical fuel pumps, they're going the way of the double action 3 spring thermostats - those that prefer them are hoarding their own private stash of replacements.

For some it boils down to a financial choice. How much have you spent trying to breathe life into your mechanical pump? And maybe more importantly, how much sailing time has been lost in the process? For those in the northeast and similar climes, the season is limited and sailing days are precious. Depending on access, switching to an electric pump might take an hour's work, start to finish (5 trips to the parts store not included).

[jerrysingle]

Seems we are having overlapping conversations but this thread seems to bring to bear the point you make about going to electric fuel pump and dump the six month project/saga I have been engaged in.

Neil brings up the point of a $40 dollar fuel pump. I really have not seen that as a solution mostly out of my ignorance of the mechanics of changing from mechanical to electric.

Any thread or documentation that outlines the switch?
:eek:

[sastanley]

<snip>

With regard to the mechanical fuel pumps, they're going the way of the double action 3 spring thermostats - those that prefer them are hoarding their own private stash of replacements.

<snip>

I have no idea who you are talking about here Neil! :D

So, is the fact that I have (almost) 3 mech pumps and the original Holley double-action thermostat as a spare a bad thing? :confused: ;)

[roadnsky]

Any thread or documentation that outlines the switch?
:eek:

IF you buy the pump that MMI sells on this site, it has very easy to follow instructions on the switchover.
If the rest of us Knuckleheads can do it, trust me, you can too... ;)

[hanleyclifford]

Sooo...Shawn - What sort of negotiable goodies do you have? I have a milkcrate full of mechanical pump parts.:D;)

[ndutton]

I have no idea who you are talking about here Neil! :D

So, is the fact that I have (almost) 3 mech pumps and the original Holley double-action thermostat as a spare a bad thing? :confused: ;)

No, didn't mean to imply anything like that. I may have an electric fuel pump with side benefits discussed elsewhere on this forum but I confess to having a spare 3 spring thermostat, vinegar soaked and stove top tested. No spacer in my future.

[ndutton]

Neil brings up the point of a $40 dollar fuel pump. I really have not seen that as a solution mostly out of my ignorance of the mechanics of changing from mechanical to electric.

Any thread or documentation that outlines the switch?
:eek:

When I threw out the $40 figure it was for the pump only bought through a discounted source. There are other parts necessary to complete a proper installation. If you prefer a complete package kit, as Roadnsky Jerry said there's one available on this site:

Here ya go (http://www.moyermarine.com/cgi-bin/shopper.cgi?preadd=action&key=FPMP_10_52)

It will save you the forewarned multiple trips to the store. Maybe the parts department here could provide you with installation instructions so you can determine whether you want to take on the project. My opinion is it's easier than what you've already been through.
and dump the six month project/saga I have been engaged in.
Six months, really? Your old fuel pump is sending you a message. I expect there are plenty of old skoolers around here who'll be happy to take it off your hands.

[sastanley]

Sooo...Shawn - What sort of negotiable goodies do you have? I have a milkcrate full of mechanical pump parts.:D;)

Hanley, i am an A-4 newbie. I have only managed to procure one extra carb and since I have converted to the plate and single action t-stat, my original 3-spring is my 'spare'.

However, I have a friend with a Pearson 28 that is trying to put together a mechanical pump. He was going to buy the Moyer improved top section, but it looks like I don't have any spare parts to help him with the rest. I must have put them in the wrong box and pitched them. :(

I have a bronze prop shaft and a 2 blade 12" prop~ :D

[hanleyclifford]

Shawn - Next trip thru Solomons I'll have her loaded with mechanicals. Will accept Confederate dollars or Heineken. Regards, Hanley

[rigspelt]

I think I have the old mechanical pump that I replaced with a Facet electrical, sitting on a shelf doing nothing important. I think the upper housing might possibly be warped (my excuse for getting the new Facet anyway), but apparently it was working OK for the PO when we bought the boat. PM me if interested.

[2dogsfishin]

I was cleaning out my A4 carb&fuel pump drawer and found 4 mechanical fuel pumps. Anyone want them? You can have them for $5 packaging each and shipping from 32507.
I replace them with Facet electric pumps, so have no need for them. e mail me at oldflathead@bshmarine.com

Tom

[sastanley]

I just finished rebuilding another spare that is ready for service...if you guys can convince me to quit hoarding them and come further to the dark side at the next opportunity, I may be convinced. Maybe I just don't know any better. :rolleyes: :confused::D