Just got back from the Dealer and LP and IP "test" fine. They said the fuel filter cap was loose causing air into the lines causing the fluctuation in FP, they tightened the cap problem resolved to them. I pickup the truck tonight and the same thing 16psi idle and then for no reason 9psi idle down to 2 or 3 WOT.

Could there be air getting into the fuel lines causing the fluctuation in pressure or is this the new method for dealers to get out of warranty work. They did test the LP 3 times according to my papers and got 48oz or more each time. Don't know what the pressure readings were during the test though.

At this point I'll buy a walbro or FASS to save the IP, my dime now I'm out of warranty in less than 2 weeks.

Any thoughts?

TIA.

 

I have had 5 or 6 LP on my truck and none of them ever showed more than 13psi at idle. Most showed around 10-11. That is after the filter and with a new filter installed.

Keith

 

I've only changed my LP once in the last 2 years of owning the truck. First LP read 15psi at idle when I bought the gauge slowly down to about 12psi idle down to about 5psi WOT and then I changed it. This one has always read 16psi at idle ~8-9psi WOT until recently and now I'm having this fluctuation, like I stated before dealer says air in the lines, could it be true? I have Autometer Ultra Lite gauge plumbed at the shrader valve on the VP no isolator just a needle valve in line?

 

You can get some clear hose and put it in between the filter and IP, and if you see bubbles, you're obviously getting air somewhere. Then the next step is to pinpoint where. Could be a leaky fuel heater in the cannister, although you should have a visible leak. Could be a restiction on the suction side of the LP causing this.

 

If it was air in the lines your truck would probably be running rough or at idle or showing some kind of symptoms.

Keith

 

Your LP is going dead, I really like the dealer story though.

 

Air suction would not cause this sort of fluctuation, I think. It is the lift pump going south. I am amazed that the dealer actually didn't insist on putting a $400 in-tank contraption in your truck. That is one honest dealer. Or, clueless.
-P