Manual Prime on 2007 FG140 not working

Fusooka

Member
After recently draining water from the fuel filter casing I was unable to get suction on the manual prime (to purge any air in the line). Fortunately no air made it into the line and the truck ran fine. Had the local diesel mechanic take a look and he was also unable to get suction so I called Mitsubishi and was told the pump is integrated and I need to replace the entire casing. This seems odd given that the pump appears to attach to the casing via four screws and can be removed? Has anyone had a similar experience and, hopefully, a solution short of replacing the entire casing? My FG only has 60,000 miles on it so a problem like this seems a bit premature...
 

SkiFreak

Crazy Person
I have found the OEM primer a bit hit and miss at times. In my experience it does not like pumping air, which kind of defeats is prime function.
What I have done in the past is to connect a clear bleed hose to the bleed nipple and used a large syringe to suck fuel through the filter. When I am getting mainly fuel, the primer then does its job.
Having said that... sometimes the primer just works without doing any of the above.

I have also seen that some other people have connected an after market primer in the line and not relied on the OEM primer on top of the fuel filter.
 
Last edited:

boostin

Adventurer
Story of my life ha ha, I even bought a new assembly which was surprisingly cheap.


My original one both bleeders broke off.

I have yet to have it prime, but I was told that unless you have half tank or more it's hit and miss.

If course I do my maintenance whole in the e line lol.

But yes adding some vacuum to the bleeder makes bleeding air a one minute job
 

Fusooka

Member
Suction via syringe seems like a reasonable, low cost alternative....I'll give it a try. Thanks for the suggestion. Cheers!
 

kerry

Expedition Leader
How much vacuum does it take to suck the fuel thru? Could a person suck it thru with their mouth, using something like a soda bottle with an in/out hose to catch the diesel to avoid ingestion.
 

SkiFreak

Crazy Person
Not that I haven't done it myself over the years, but sucking on any fuel line is not something any doctor would recommend.
Even with any form of catch pot, you still ingest the fuel vapour, which is not what your lungs were designed to take in.

To digress a bit here...
I have also fitted an inline valve into the fuel pickup line, between the fuel filter and the tank. This allows me to close off the fuel line when changing the fuel filter. The benefit of this is that if the fuel level in the tank is lower than the fuel filter (which it usually is) then I do not get any drain back into the tank. When changing the fuel filter I fill the bowl with diesel then replace it. Normally this negates the need to prime the system at all; it just works!
The added bonus of the shut off valve is that it can also function as an anti theft device. When closed you get about 20 metres before the engine cuts out. You can probably figure out how I found that out... ;)
 

SkiFreak

Crazy Person
I think that the shut-off valve you have linked to Kerry is a bit small for a Fuso pickup line. I have custom fuel lines in my truck that I made up from 1/2" stainless pipe and I used a full flow plumbing valve for the shut-off.

If you want to see how I did mine Bris, have a look at the images in the A new fuel tank setup article on my website. The fuel shut-off valve is the one with the red handle. There are two images there that show it pretty clearly.
 

pugslyyy

Expedition Vehicle Engineer Guy
The added bonus of the shut off valve is that it can also function as an anti theft device. When closed you get about 20 metres before the engine cuts out. You can probably figure out how I found that out... ;)

I have a shutoff valve that I manage to knock into the off position almost every time I pull my tool box out, I know all about that anti-theft feature...
 

unkamonkey

Explorer
I've never had a problem priming my old beast but I know it is a different engine and fuel system. Filters, fill them up with fuel and screw them on. I changed to a larger fuel tank. Wire up the hoses and then hook them to the new tank. I was prepared to do the manual pump bit after the new tank. Huh, the thing ran fine?
 

pugslyyy

Expedition Vehicle Engineer Guy
I've never had a problem priming my old beast but I know it is a different engine and fuel system. Filters, fill them up with fuel and screw them on. I changed to a larger fuel tank. Wire up the hoses and then hook them to the new tank. I was prepared to do the manual pump bit after the new tank. Huh, the thing ran fine?

I'm not sure about how the 92 is set up, but my vintage is a common rail system which is much more tolerant of a bit of air in the system as long as there is fuel enough at the injectors to start.
 

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