Mysterious air lock

[crash86]

Okay Ive been battling this for a few months now and cant resolve my problem. I can start it up and it blows white. It continues to constantly blow white smoke until the motor warms up. I can be driving down the road and its running fine then after about 5-10 miles it will start to pick up air in the fuel and die. We've put an electric fuel pump in conjunction with the mechanical pump, we put an in-line filter in before the electric to catch debris. Also we changed tanks because there was a build up of rust and we thought that was the problem, but apparently not. We've changed all the fuel filters, we knocked the bb out on the injector pump thinking the pump was building up too much pressure and we've even taken off the gas caps thinking it was vapor lock. Idk what else to try. Any ideas or suggestions would be greatly appreciated.
Thanks

 

[yARIC008]

Did you replace all the olives and the O-ring on top of the filter housing for the fuel heater? That was my problem with all my leaks. Have you install clear lines on the return to see if air is in-fact moving though the filter? Also, caution on the electric pump inline with the mechanical pump. Your mechanical pump diaphragm fails and you'll be filling your engine up with fuel, even more so than you would under a normal failure.

 

[icanfixall]

What fuel level are in both tanks when this happens. If they are at 1/4 tank or less you probably are sucking air. these tank suction pickups break off and the last 1/4 tank can't be sucked out. You will know this if the truck runs out of fuel and a refill of the tanks only takes around 12 gallons. Also if on e tank is not being used because its damaged you may have a tank switching valve issue. Sometimes crap keeps the switching valve from completely changing over to the other tank. then you suck up air... Best of luck sorting this out too..

 

[crash86]

What kind of problems did you have with the O-rings? Was yours dying and blowing white smoke like I said mine was? or is that another different problem?

 

[riotwarrior]

Have you replaced the rubber fuel line at the mechanical lift pump? From the metal feed line to the lift pump?

 

[crash86]

Yes. We've checked all the fuel lines

 

[dgr]

Did you install the electric pump before the water separator? If not, I would plug the hose hanging behind the left front wheel well in case air is getting sucked in there

 

[crash86]

The water separator is after the electric pump.

 

[John Deere]

Are you sure that there is air in the system? Reason I ask is I had the tank selector valve fail once, and it would prevent my fuel from returning to the tank and cause my engine to stall out, I can't remember if the other symptoms were similar though.

 

[crash86]

I've tried bypassing the selector valve and it still stalled out on me.

 

[John Deere]

If you are sure it is air in the system, you need to install clear lines in various places of your supply and return lines so you can isolate where the air intrusion is happening.

 

[hesutton]

The stock water separator is notorious for causing major air intrusion. Have a really good look there.


Plus, it's not a good idea to plumb an e pump inline with the mechanical. If the diaphram in the stock lift pump is marginal, it can crack with the added pressure/fuel the e pump is pushing into the mechanical.

Heath

 

[crash86]

I dont have the stock water separator on anymore. I suspected that was the problem before so I took it out and put in an after market water separator

 

[redneckaggie]

had this happen and the problem was the plastic lines leaving the selector valve were sucking closed, installed sleeves in those lines and it worked out fine, what kind of electric pump, where is it mounted, have you tried removing the filter before the e pump, are you sure that there isnt something blocking the suction in the tank?

 

[crash86]

We mounted the pump on the frame before the selector valve, we havent tried removing the filter, but we have taken it apart and cleaned it. We installed a new tank as well.