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Diesel filter won't prime

John Packham

Active Member
Joined
Dec 9, 2011
Messages
51
Hi guys

I've changed the diesel filter on my 120 - the old one showed it was doing its job but wasn't too bad - with a new one from Bosch (no cheapo parts on my cruiser) and I can't get it to prime. I've tried for several minutes and nothing! The various videos on YouTube make it look like a couple of dozen pumps and it's done. Took it out again and it is dry. There's about a quarter of a tankful of fuel. I can't easily try filling the filter via the inlet pipe with a funnel because I have no diesel lying around. I'd be surprised if there's a failure in the primer - this car is 100% reliable and never seems to need parts!

Any ideas?
 
Bad seal on the filter? Are you tightening it too much? Lubed the seal?
 
Bad seal on the filter? Are you tightening it too much? Lubed the seal?
About half a turn by hand and the seal was pre-lubricated.

Just stripped it and re-checked, the seal's fine but the filter is bone dry.
 
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What I normally do John is loosen the bleed nipple after the fuel filter then undcrew the hand pump and after 4 or 5 strokes the filter is full. I then nip up the bleed nipple and push the pump down and tighten again. This is on a 60 though so may differ. Not sure if this is helpful or not.
 
Primers playing up the one way valve or the diagrams split, I never use mine, just crank it over and hold throttle to the floor, it'll go eventually.
 
I've solved it. It was simply a matter of air and the priming pump not drawing the fuel initially.

If anybody else has this issue, here's what to do: Get a small funnel and a length of fuel pipe and connect it to the inlet of the fuel filter housing, fill the funnel with diesel and then prime the filter. Once you feel any resistance on the primer, you're there. Simply reconnect the inlet pipe and continue priming as normal.

My initial problem is I had no spare diesel but I solved that by siphoning a bit.
 
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Mechanical on an 80, same principal on all diesels, except the ones which the manufacturer doesn't fit a primer pump, which is the stupidest idea in the world.
 
I've solved it. It was simply a matter of air and the priming pump not drawing the fuel initially.

If anybody else has this issue, here's what to do: Get a small funnel and a length of fuel pipe and connect it to the inlet of the fuel filter housing, fill the funnel with diesel and then prime the filter. Once you feel any resistance on the primer, you're there. Simply reconnect the inlet pipe and continue priming as normal.

My initial problem is I had no spare diesel but I solved that by siphoning a bit.
So you've solved the primer by priming the primer, still a fault in the primer, it should just lift fuel by pumping it, if it doesn't it's faulty.
 
We had this when @Shayne changed his fuel filter on the way to Romania. I eventually got Shayne to pull the return line off his tank and put his thumb over the pipe from the tank. I then put the air line from my compressor in the filler and closed off around it as best I could. Soon got the cruiser going, but as you say, it hasn't fixed the issue of a valve sticking, which must be the case as a broken diaphragm would leak or let so much air in as to stop the engine or at least make starting difficult.
 
There is a sure fire way of getting a Cruiser primed in no time and always works. When I replaced the injectors in the original 80 it wouldn't bleed up within 3 or 4 mins.
With a blow gun and a cloth wrapped round it to seal I introduced compressed air into the tank ( not excessive) and it bled up straight away.
This always works assuming you are in the workshop or have on board compressed air.
 
Just for reference I changed my fuel filter yesterday and I primed it with about 20 pumps and started first time
 
I have used pressure in the tank before, another tip is to swap the filter on a full tank of fuel as the demands on the primer are less.
With the filter removed fuel should easily pump out of the housing if not I would suggest the primer is shot.
 
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