Hi all

Today I did a service on my Yanmar and I have replaced the original filter element after the lift pump and I have also replaced a ancient fuel filter between the tank and lift pump with a new CAV unit

The fuel tank on mine sits behind the engine at about cylinder head height, the CAV filter sits under the engine and the original filter probably just below the tank height

I assume that if I block the outlet on the CAV filter and open the bleed screw on top the CAV filter will fill

I have to replace the flexible hose between the CAV and the lift pump so when the CAV is full and the air has bled out of it I will connect the new hose to the outlet of the CAV and hold the other end of the hose just below tank level and it should bleed the air out of the hose and fill with fuel and then I will pinch it off

If I then connect the end to the lift pump I should be able to pump fuel into the original Yanmar filter and bleed the air out of it and get the thing to start

Does anyone see any problems doing it this way because when I have replaced both of the existing filters before and tried to pull the fuel through the system with the lift pump manual lever it has taken a long time to get the fuel up

Regards Don

This has been discussed before.

The fuel lift pump is a small diaphragm pump with a low delivery rate. It only needs to be able to deliver marginally more fuel than the engine will use at full fuel rack position. Your engine would probably consume less than 2 litres of fuel per hour at full power like my engine.

Therefore using the priming lever on the fuel lift pump will be time consuming to say the least and especially so if the internal lever is not on the back of the fuel pump cam.

For about $30 you can buy a CAV diaphragm pump which is fitted to the inlet side of the CAV filter. It has probably has a 25 ml per stroke delivery rate and will bleed your primary filter (the CAV one), your fuel lines and your secondary filter (the Yanmar one on the engine) in about a dozen strokes of the pump, eliminating use of the fuel lift pump lever altogether for bleeding the system.

In fact if you fit a double CAV filter module, the first filter having a glass water trap of course, you could eliminate having a paper element in the Yanmar filter on the engine altogether.

When the whips are cracking you want to be able to bleed that fuel system as quick as possible.

Another option is to fit an electric fuel pump between the tank and primary filters. I am not a fan of that idea on a small boat. Something else that can fail when you least expect it.

My motor has a old outboard hose bulb pump after the fuel tank you squeeze the bulb and pushed the fuel through the system personal it works but I'm not over joyed about it Donk The cav would be my choice


This is the sort of unit Cisco mean I think
Ill be going through my fuel system later on

http://www.ebay.com.au/itm/like/131349762934?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=107&chn=ps

you can see my fuel priming pump above off a outboard

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cisco said..

This has been discussed before.

The fuel lift pump is a small diaphragm pump with a low delivery rate. It only needs to be able to deliver marginally more fuel than the engine will use at full fuel rack position. Your engine would probably consume less than 2 litres of fuel per hour at full power like my engine.

Therefore using the priming lever on the fuel lift pump will be time consuming to say the least and especially so if the internal lever is not on the back of the fuel pump cam.

For about $30 you can buy a CAV diaphragm pump which is fitted to the inlet side of the CAV filter. It has probably has a 25 ml per stroke delivery rate and will bleed your primary filter (the CAV one), your fuel lines and your secondary filter (the Yanmar one on the engine) in about a dozen strokes of the pump, eliminating use of the fuel lift pump lever altogether for bleeding the system.

In fact if you fit a double CAV filter module, the first filter having a glass water trap of course, you could eliminate having a paper element in the Yanmar filter on the engine altogether.

When the whips are cracking you want to be able to bleed that fuel system as quick as possible.

Another option is to fit an electric fuel pump between the tank and primary filters. I am not a fan of that idea on a small boat. Something else that can fail when you least expect it.

Hi Cisco

Can you post a link to the primer pump that attaches to the inlet side of the fuel filter

Regards Don

http://www.ebay.com.au/itm/Universal-Fuel-Filter-Assembly-with-Primer-Pump-CAV-Tractor-Bobcat-Truck-etc-/221623103204?pt=LH_DefaultDomain_15&hash=item3399c42ee4




www.ebay.com.au/itm/DIESEL-FUEL-FILTER-HEAD-ASSY-HAND-PRIMER-UNIVERSAL-CAV-CITROEN-FORD-LDV-DPT1005-/301536662821?pt=LH_DefaultDomain_3&hash=item4634fc5525

this is what you want some thing like this above
www.ebay.com.au/itm/HILUX-SURFLN130-DIESEL-FUEL-FILTER-PRIMING-PUMP-HOUSING-ASSY-51-POST-FREE-/391058264771?pt=LH_DefaultDomain_15&hash=item5b0ce392c3

I would even have a look at the local wreckers donk at diesel utes Toyota ect

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HG02 said..
http://www.ebay.com.au/itm/Universal-Fuel-Filter-Assembly-with-Primer-Pump-CAV-Tractor-Bobcat-Truck-etc-/221623103204?pt=LH_DefaultDomain_15&hash=item3399c42ee4

Hi HG

Thanks for the link and i might see if i can chase one up for future filter changes

I had planned to slip her today until saturday to antifoul but when i asked a couple of weeks ago i was told the slip was booked till saturday so i booked for next friday and decided to service the engine instead and pulled the water pump off and bought it home to replace the impeller and disassembled the fuel feed thinking i had 3 easy days to do the work

I got a call from the club member who runs the slip this afternoon saying the slip was now available as the guy came off early and i told him i would have mine running by tomorrow lunchtime (i have a doctors appointment at 9.30 am that is a bugger)

When i pulled the pump apart late this afternoon i found i had been given the wrong impeller so i made a mad dash to the boat shop to get one (he had one instock) and ended up buying all the anti foul stuff i needed as well that i was going to get next week

So the job tomorrow is to put it back together and get it running so i can get it on the slip anf give her a blast and a couple of coats of paint while i am on holidays

Hopefully if i can gravity or suck the fuel as far as the lift pump inlet the manual lever on the Yanmar lift pump will do the rest without to much drama

Regards Don

Hi Donk
I think the best way to find the right fliter and priming pump is go to a fleet guard or Donaldson dealer find the cheapest common spin on fuel filter and once you find that buy a priming fuel diaphragm housing to suit that fuel filter.
In doing this the initial cost maybe a little high but next time you need a filter any truck shop around Australia will have one in stock, I did this a while ago but didn't go through with it yet but will. I think the spin on filter was around $6 to $7 I did give bubbles a fuel filter and housing but it did not have the primer on the housing. Do not buy the plunger style primer pump only a diaphragm style . diaphragm below


this is the sort of thing you should try for but find a comon fuel filter that will fit the housing thats cheap to replace the filter and would be in any country town truck shop . bit like buying a holden filter and a BMW filter ones a little more expensive


I'm not sure right now but this i a Donaldson is under $7 but a filter dealer will set you right donaldsom Wixs or Fleet guard

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Donk107 said..


Hi Cisco

Can you post a link to the primer pump that attaches to the inlet side of the fuel filter

Regards Don

The one I have is this one that HG posted an ebay link to which I think is the simplest and most generic.

http://www.ebay.com.au/itm/Universal-Fuel-Filter-Assembly-with-Primer-Pump-CAV-Tractor-Bobcat-Truck-etc-/221623103204?pt=LH_DefaultDomain_15&hash=item3399c42ee4

It can be turned around to the best position for your individual set up.

I prefer the CAV filters over the spin on Donaldson type because if you are running short of filter elements the CAV elements can be washed with diesel and reused at a pinch.

The only reason i like the spin on filters is you can fill them with diesel before you fit them and some times bleeding is not needed

Hi all

because of some unforeseen problems I ended up connecting everything up and with the tank near full and the fuel level higher than the rest of the system it only took around 20 pumps of the lift pump lever to get fuel through and the air out and she started without any drama's

She is on the slip now and tomorrow I will roll on a couple of coats of antifoul

Regards Don

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HG02 said..
The only reason i like the spin on filters is you can fill them with diesel before you fit them and some times bleeding is not needed

Good point. The CAV with the glass bowl will not pass survey in NSW either. Always struck me as weird, the problem cited was its a problem with engine fires yet you are a allowed a short lenght of flexible rubber fuel hose to the engine!

nothin wrong with the outboard primer bulb on a diesel HG
have seen quite a lot fitted to yacht engines over the years
they can prime a diesel system very fast any time, a good
safety system I think

I agree Radar, I keep one in my toolbox with various hose and a few fittings for priming up fuel pumps. I've had to use it on various types of vehicles usually because of filter top type primer pump failure

I put a hand primer pump between the tank and CAV filter. It is fantastic and cost a few bucks and 30 minutes to fit. Nothing else is needed.

When I had the survey done the surveyor was not impressed with it, thats the main problem. Ive used a few times and find it very easy and quick to use and very reliable . I think Ill leave it in and just replace all the fuel lines when I go through the fuel system

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Jolene said..
I agree Radar, I keep one in my toolbox with various hose and a few fittings for priming up fuel pumps. I've had to use it on various types of vehicles usually because of filter top type primer pump failure

I have always like the diaphragm pumps rather than the the piston style bleed pumps the piston design never seem to last on just about every Diesel engine Ive serviced

I find these reliable every time but the piston style below unreliable

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MorningBird said..
I put a hand primer pump between the tank and CAV filter. It is fantastic and cost a few bucks and 30 minutes to fit. Nothing else is needed.

Ditto :)

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[b]HG02 said..

I have always like the diaphragm pumps rather than the the piston style bleed pumps the piston design never seem to last on just about every Diesel engine Ive serviced

Yeah, I don't know of a piston/plunger pump that lasts, or do I know of a diaphragm pump that lasts. But at least the plunger pump on most engines has serviceable parts, you can usually strip it down and get it working,,,, serviceable parts that are often forgotten about,,,
I don't favor one or the other, one is serviceable the other you throw away,, but when the diaphragm type is stuffed your stuck, that's when the outboard hand primer comes in handy.