Engine/Transmission (1998.5 - 2002) one more LP change? about purging air.

[JCyrbok]

Anyone see a problem with attaching a air cond hose with a schrader female end to the inlet schrader of the fuel filter housing and bumping starter to purge the air/prime the LP after the change?



Reason I ask is that in theory it looks like it would be easier and less mess than loosening the banjo on the oulet of the filter. I also have my FP gauage hooked up to a tapped banjo at the VP so that Schrader is not there. Seems that it would be better to get the air out of the system before it even made it to the filter.



Alternate method would be to just hold the schrader valve in, but would be much more messy!



Anyone with an opinion, good or bad please let me know. LP is getting changed on Sunday regardless, but would like it to be as easy as everyone makes it out to be.



Thanks

J-

 

[Thomas]

Since you're proposing opening the system to purge air at the inlet to the filter housing are you assuming that removing the transfer pump will leave the filter housing full of fuel?

 

[JCyrbok]

I assume that it should, since the inlet of the filter is basically at the highest point of the side of the houseing. I figure that if you removed the fitler inlet banjo and then removed the intlet to the LP that the fuel would not run out of the filter as it would be slightly lower then the inlet of the housing. Does this seem right?



also I assume that since the outlet of the fitler housing is lower than then inlet to the VP that the fuel would not "gravity" flow up hill, through the VP to the return and back to the tank. Does this seem right too?



Well it all may be a mute point as there is no schrader on the inlet of my fuel filter housing, despite the shop manual saying there should be and that fact that DC is supposed to pressure/drop test the filter as part of the diagnostics on the LP. How are they doing this with out a Schrader pre and post?



Oh well if it looks like my purging scheme will work let me know and I can replace the inlet banjo to the filter with the schrader that I removed when I replaced the schrader for the FP gauage.



PLease let me know if my reasoning is on track here or if I'm trying to make an easy job easier.



Also any other idea's to purge the air out of the system to prime the LP would help. Thats the only part of the job that somewhat worries me. I dont want to get too much air in the lines and have to crack injector lines. This is going to be a one person ( me) operation on Sunday.



Thanks

J-

 

[Thomas]

My one experience with a transfer pump change on my model year 2000 Ram (should be identical to model years 2001 & 2002) was my hardest re-start after any opening of the low pressure fuel system. I eventually cracked the banjo at the inlet to the VP-44 to purge the air. I think the further along in the low pressure system you let the air out the better off you'll be. Even though your pressure monitoring system uses a tapped banjo bolt at the VP-44, unless you have rigid plumbing to your fuel pressure gauge (or fuel pressure gauge sender) you should be able to come up with a way to bleed air there.