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4jg2 mu fuel issue

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4jg2 mu fuel issue

Postby RyanE123 » Sun Jan 31, 2021 3:33 pm

Hi guys

I have just put a 4jg2 with manual fuel pump back into my mu and having some fuel issues.
After bleeding the system I can get the engine to start up and run mint. Until I turn it off. Once turning it off I can start the engine again to have a few misses for a few seconds.
But if I leave it overnight the system needs to be rebled for it to run again.

Things I have done

Replaced fuel filter
Replaced injector heat shields
Put a clear hose from the primer pump outlet to the fuel pump to see if any air bubbles... no air bubbles.
Put a clear hose between the primer pump inlet and chassis rail hard fuel line. no bubbles
Put a clear hose between fuel return rail and injector pump and no fuel at all, is this normal?

before putting the engine back in i didn't have these issues.

Anyone had any issues similar to this, or is there anywhere I can start looking to resolve this?
RyanE123
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Re: 4jg2 mu fuel issue

Postby geeves » Mon Feb 01, 2021 5:28 am

Most common cause is the fuel filter. Double check both seals. Also what is the history of the fuel pump? Front seal on the pump can also cause this
Sanding your knuckles before starting work can help. That way you cant skin them
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geeves
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Re: 4jg2 mu fuel issue

Postby RyanE123 » Mon Feb 01, 2021 6:02 pm

I have no idea on history of fuel pump i'm the second owner of the vehicle and previous owner owned since new and kept everything upto date. So I would assume he could've got it serviced. not 100 percent though. Have taken the fuel filter off and double checked seals a few time now all look good. clear hoses between filter assembly show no bubbles, have just replaced all hoses from the engine side with new clamps today, still has the same issue. Is there a way I could tell if fuel pump has as issue? Once i have bled the system it runs perfect. no issues at all, it is only when the vehicle has been shut off for 30 minutes or longer. if shut off for ten minutes though the engine will miss for a few minutes then come right so it's definitely sucking in air from the get go.
RyanE123
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Posts: 10
Joined: Thu Jan 07, 2021 12:35 pm
Age: 26
Country: New Zealand
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Vehicle: Isuzu Mu 3.1
Isuzu Trooper 3.1

Re: 4jg2 mu fuel issue

Postby geeves » Tue Feb 02, 2021 9:37 am

Once you eliminate everything else the last thing you look at is what it is. Check all fuel lines first. Also the drain tap in the bottom of the filter
Sanding your knuckles before starting work can help. That way you cant skin them
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geeves
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Re: 4jg2 mu fuel issue

Postby RyanE123 » Tue Feb 02, 2021 3:30 pm

Yup that's normallt the case, do you have the part numbers for the fuel pump geeves? i have just put clear hose on every fuel line and turned engine on. Once running the return off the pump to tank is getting decent bubbles, once off these bubbles start to return back to the fuel tank.
RyanE123
Isuzu Baby
 
Posts: 10
Joined: Thu Jan 07, 2021 12:35 pm
Age: 26
Country: New Zealand
City: Napier
Vehicle: Isuzu Mu 3.1
Isuzu Trooper 3.1

Re: 4jg2 mu fuel issue

Postby geeves » Wed Feb 03, 2021 10:45 am

Its probably just the front seal you need to do but it does mean striping the front of the engine. Might as well change the timing belt at the same time. Its an expert classification on the difficulty scale. Might be worth talking to a local diesel mechanic who should be able to do it for a few hundred although they will want to recon the pump which will be 1000 to 1500
Sanding your knuckles before starting work can help. That way you cant skin them
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geeves
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2013 Subaru XV

Re: 4jg2 mu fuel issue

Postby RyanE123 » Mon Feb 08, 2021 12:20 pm

i've just rebuilt the engine over the last year, new fuel pump in the other day.
I think i'm onto something here, havee miniscule air bubbles now through the outlet of the pump but not the big bubbles like i had last time,
RyanE123
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Posts: 10
Joined: Thu Jan 07, 2021 12:35 pm
Age: 26
Country: New Zealand
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Vehicle: Isuzu Mu 3.1
Isuzu Trooper 3.1


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