I have a 2005 Cat D4G with the Mitsubishi Engine. Have removed the Fuel Tank a few years ago to have it cleaned and lined because of rust problems. Use to have all kinds of problems keeping it running until I did that. The symptom before I had the tank cleaned was it seamed to get air starting in the fuel seperator in the rear and then air would get into the secondary filter. Figured it was sediment in the tank from being rusty. Anyways for two years after cleaning the tank no problems. Then recently it started again. Checked for the obviousl, changed filters and still happens. I have drained the tank and looked inside. Liner material is still intact. Cannot find anything in there that could be floating around inside the tank to block the intake line and possibly cutting off fuel flow. Like I said no problems for two years until recently. What could possibly be the causes of air in the water seperator filter and the secondary. It is so bad when it happens that when you unscrew the blead screw on the secondary you can hear it the vacum lock.
You have something in the fuel line between the tank and the water separator ,try blowing the line out. Bob
Yup.. the pumps sucking or TRYING to suck the fuel & cant.. vacuum=blockage.
My D4G was bad about getting trash into those little elbows right before the water separator that you're talking about. It was a common problem on that series according to my dealer.
When this happen I took a portable air tank out and blew the line and could hear the bubbles in the tank. What I did was took the Water Separator Off and blew air in the center hole. It ran better for a few weeks but then it acted up again. I blew it again. The mechanic at the equipment place I take my dozer said that maybe the lift pump is weak. This dozer has about 5500 hours of which I have put 3000 of those hours.
This tells us you have something in your tank. Bob
Air can blow out the little stuff like fuzz and tiny bits of vegetation that find their way into fuel and into the tank. You might have a piece of something bigger stuck that won't block fuel until it builds up a dam of little trash that would ordinarily go right through the pump and get trapped in the separator or filter. You can either take the pieces apart and check them, take them apart in smaller segments and blow through them, or get a vacuum/pressure gauge (like $10) and tee it into the suction line to see what happens. Any rubber lines should be replaced.
I will be taking it to the mechanic next week. He did mention rubber hoses breaking down inside. He was not sure where the rubber hoses were in the fuel system of my D4G. My prefix is CFN. It looks like the line coming from the tank to the water separator is steel. When the line leaves the separator and go goes forward it is steel for what I can see but I think I have seen a drawing where the steel morph's into a rubber line moving forward towards the engine compartment. Thanks all for listening and giving your answers. My name is Ron
If your transfer pump pulls that much vacuum I drought it's bad ,If they change it make sure they clean the tank. Bob
Good call Bluox.. ya beat me to it.. [#9]
Those plastic priming pumps on top of the filter separator housings are bad about leaking air into the system too. Unscrew it and check to see if there's trash in the top of the filter housing. Air won't get rid of chunks that are lodged in there. I agree that you have trash in your lines or tank.
This is the water separator that is on my D4G. The housing this goes into has a hand pump on top of it. Is that the plastic priming pump.
Like d9g says, the primer plunger can leak air into fuel system if oring/gasket is bad. Easy thing to test and rule out
Yes it is.
Sorry to ask this hear, but i would like to print this out to have with me when I visit my mechanic. Does anyone here know how I can do the printing?
I'm assuming you are asking if you can print out this whole discussion? That is a good question! I looked around some but did not see an obvious way to do it. Maybe some one of the moderators will stop by and let us know if it is actually possible? One crude way would be to start a text file on you computer and then highlight one post at a time and copy and past it to that file then print from there. If that does not sound easy for you I could do it and then email you the file so you could print it out. If you want to do it that way click on my name over to the left and when the box opens up click on the "Start a Conversation" and send me an email address to sen it to.
Anytime I have had air in the fuel system it accumulated in the filters, there was a slight leak in the fuel line from tank, it would suck air but not leak fuel. Happened on 2 scrapers
Just hold down the Ctrl button and hit the P key. Then pick which printer that you want to send it to.
I like the ctrl button option!!! Didn't know it existed.. On mine, top left, where it says "file, edit, view, tool, ect.. if you hit "file" a print option will come down..
Update on the problem: Pressure at Lift Pump is about 1-5psi at best. When they took fuel cap off the tank it had a vacum on it. Tank is not full only got about 10 gallons of fuel in it. Found one of the lines at the lift pump with a crack in it near the fitting. Going to look at Lift Pump more closely but it looks like a new lift pump might be in order. Does any of this sound right?
Could be something as SIMPLE AS a bad fuel cap.. They HAVE TO BE vented.. its not uncommon for the vent hole to become clogged w/ "stuff".. happens ALL THE TIME.. Just loosen it & see of it runs ok.. The vacuum is created by the lift pump Sucking & no fuel being delivered.. Just like putting your finger over the end of a straw.. SO, you either have a blocked pick-up tube/filter in the tank or the vent in the cap is clogged.. ALL EASY fixes..
I had an idea there was a way to do it! Thanks now I just need to store that one in memory banks somewhere!
Vacuum in tank does not sound right! I don't seem to recall if there has been an attempt to take the suction line off the filter and connect a short hose to a can of fuel to see if primer pump will pump good when sucking straight out of a can. Just for fun I had to look on SIS to see the tank and cap arrangement a D4G had. It is the same as just about all the newer Cat's I have worked on. When was the last time that cap has been rebuilt? Except on the cleanest machines I made it a habit of at least once a year rebuilding the caps. Kit number 9X2205 as shown in picture below for $29.33. In a pinch you may be able to just disassemble and clean the various small parts, filter and check valve.
2 years ago. When they cleaned the tank I bought all new fittings and a new tank cap to put on it. I will have them check the cap for debris. I already did before I took it to the mechanic but I did not see anything.
Update: Picked up machine from shop today. They replaced all the rubber fuel hoses and found some debris/rust in the water seperator when they removed the two screws. Fuel Pressure is back up to about 18psi (I think that is what he said). When I took it in it was real low. They seem to think that it was sucking air thru the rubber hose. We will see how it goes. Thanks for all your replies and thoughts about my problems.
So far so good. The final solution of replacing the rubber lines in the engine compartment and the removal of debris from the lines leading from the tank to the water seperator seemed to solve the problems. Been running it hard for about 100 hours and not even a sputter. Thanks for all your input. Consider this solved on my end.
Good deal.
Tank should not have a vacuum on it check vent I don't think your pump is bad. Pull the lines and fittings off from the tank to the transfer pump blow out run wire thru the fittings make sure the is no restriction and check tank to make sure that the lining you had put in is not flaking off