air in fuel line no cracks or holes

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air in fuel line no cracks or holes *SOLVED*

so I searched the forum and didn't really find anything with the same problem. The closest was a suction side air leak.

basically this only effects me with the initial start in the morning and it will run a little rough as though it's not getting enough fuel for about 10-15 sec or a little more when it's cold. After it's warm the problem is gone for the rest of the day.

so I had my mechanic check all the lines as well as the lines from the fuel tank. He said that there was no leaks at all and is confused where the air could be coming from. He ended up taking a container of diesel and running that to the pump and some how air is still getting in. Does this sound like a suction side air leak or is it the fuel pump itself?



John
 
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my mechanic said he checked the low plugs and they are in good shape. He confirmed it is air in the system... can't actually remember what he said but he was able to confirm the air in the system is what's causing the rough initial start.
 
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Sounds to me like maybe a blocked filter? Take the fuel line off closest to the injector pump and replace it with cheap clear pvc tubing and look to see if there are air bubbles, You could do the same with the fuel return pipe too and see if there is a leak in the IP. You can tell that by not seeing air bubbles going in but seing air bubbles going out.

I make bio and find if I use the fuel a little "wet" I block filters quick, and I lack power and suck air. When that happens I also get a bit of WHITE smoke for a few seconds. White smoke from what my granddad told me is air in fuel.

Maybe like my vehicle you are loosing fuel at the IP and fuel lines while the vehicle sits overnight. Just enough stays in to get you started and then it takes a few seconds for the lines to fully fill and get you enough power to roar away

I know mine does that at times because if I sit and listen I can hear it gurgle slowly back into the fuel tank. You might hear it too if you have a fuel return line from your IP. I assume it also runs back through the main fuel line but have never checked. It doesnt worry me cause i know its going to happen and I cant justify spending $$$ to fix it at the minute

Anyway dont worry too much and good luck. Its just an idiosincracy of your car
 
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hey Aussie,

so do I have to replace my injector pump or is there a fix for that?

so I found that if I park on a incline with the front facing down hill. the fuel doesn't trickle back into the tank and she fires up fine. seems to work for the moment.
 
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Fuel pipes entering the tank are a possilbe cause, i would not think its the pump as it only does it in the morning, but you never know....
Run a new pipe from the RETURN injector pipes into a glass jar of diesel(the pipe that goes back to the tank) , start it up and let it run for a minute, leave it overnight. start it in the morning, if it starts ok then its probably the pipes entering the tank.
This does not always show up as a leak, but more of an entry point for air to allow the pipe to drain back into the tank overnight. Its certainly a common problem here with LJ70's and KZJ70's in the UK.
If you are lucky you may have diesel stain on the fuel tank.

Martin.
 
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If the seal in the frount of the pump is worn it lets air in the frount of the pump. The pump is the last thing to change. The primer pump on top of your filter, have you changed this, They have a non return valve in them and they some times leak air through in the primer part on top. To check it get a pice of clear hose long enough to go from the filter to the injector pump with a loop in it that about a foot across. Have the loop top as high as the top of the filter. Pump the primer pump until their is no air in the left in the top of the loop. Drive the car for 5k . You should get no or very little air in the loop. If their is heaps . Repeat if it is still their you have a problem. If so fit ti to the suction side of the filter and repeat. If no air it is your primer pump. If the air is stil their it is in the lines or pickup in the tank. If you get no air in at all refit rubber hoses ,overnight put a set of hose clamps on the line between the primer pump and injector pump. in the moring remove it and see how it starts. try this and let me know.
 
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It could be the lift pump inside the injector pump , you can run a inline electric pump in the supply line to temp fix it .
Ive fitted a couple of electric pump with great success also saving a injector pump rebuild.
Dave
 
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Hey Ian,

ok so my mechanic ran a line from the injector pump to a canister of fuel to bypass everything... and air bubbles were still in the system so he said it is the injection pump since everything else was bypassed with his check.


john



If the seal in the frount of the pump is worn it lets air in the frount of the pump. The pump is the last thing to change. The primer pump on top of your filter, have you changed this, They have a non return valve in them and they some times leak air through in the primer part on top. To check it get a pice of clear hose long enough to go from the filter to the injector pump with a loop in it that about a foot across. Have the loop top as high as the top of the filter. Pump the primer pump until their is no air in the left in the top of the loop. Drive the car for 5k . You should get no or very little air in the loop. If their is heaps . Repeat if it is still their you have a problem. If so fit ti to the suction side of the filter and repeat. If no air it is your primer pump. If the air is stil their it is in the lines or pickup in the tank. If you get no air in at all refit rubber hoses ,overnight put a set of hose clamps on the line between the primer pump and injector pump. in the moring remove it and see how it starts. try this and let me know.
 
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Hi John. I agree with Dave, putting a electric fuel pump in, Carnt hurt it, I have thought about it but never done it. You may onley need it for start up like glow plugs, Seeing you onley have problems in the first few minites. Ian.
 
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Ok, the problem has been solved. cost a bit due to misdiagnosis on GCL's part which I am not to happy with and they scratched the hell out of my hood.

ended up dealing with a chap in Edmonton who just works on JDM's. Had a new injector pump installed and the bat tank starts fine and dandy. I guess talking with this mechanic he said that the problem is not the injector pump itself but the low sulphur diesel. Even with the fuel additives the injector pump will leak sooner or later is what it sounds like.

Well I am glad my cruiser runs smooth for the time being. It is so nice to have a mechanic that is knowledgeable with the JDM's.
 
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Your new injectors may not be seating properly. When you reinstall them make sure there is no carbon still in the holes. You may need a wire brush. If they are not seating you would be able to hear the air blowing past the seals, kinda like a ticking sound. Good luck.
 

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