Cat D4G Air in Fuel System

[thepumpguysc]

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..

 

[kshansen]

Just hold down the Ctrl button and hit the P key. Then pick which printer that you want to send it to.

I had an idea there was a way to do it! Thanks now I just need to store that one in memory banks somewhere!

 

[kshansen]

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?

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.

 

[roostertn]

..... When was the last time that cap has been rebuilt?
View attachment 177890

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.

 

[roostertn]

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.

 

[roostertn]

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.

 

[d9gdon]

Good deal.

 

[Dave Neubert]

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