d'max fuel system questions, need help

[hapaschold]

i've got a some questions pertaining to the fuel system on the d'max. many thanks in advance for any help .

- is there a lift pump to prime injector pump ?

- what is the fuel line pressure in the supply line to injector pump at idle ? and under load ?

- what is the fuel line pressure in the return line to the tank at idle ? and under load ?

- any idea on the % of how much fuel is returned to tank from injector pump during idle and under load ?

- any thoughts on the diesel fuel "air eliminators" on the market that claim to increase engine effiency, decrease emmisions, etc. , by removing air trapped in fuel ????

thanks again, sorry for long post.

hapaschold

[TLA]

'Hope this helps. There is no lift pump, hence there is no pressure to the injection pump. The pump creates a negative pressure (vacuum - reputed to be 60" of HG.), so from the tank foreword, the lines and filter have a vacuum.
At idle, the fuel return has some pressure, but I couldn't guess how much. Not a lot of volume, either.
No idea how much is by-passed. I'll try to get a look in the shop manual.

[hapaschold]

thanks TLA<

really appreciate your time, it s mucho appreciated.

hapaschold

[hapaschold]

thanks TLA<

really appreciate your time, it s mucho appreciated. :D

hapaschold

[jbplock]

From reading the various fuel filter threads, I've gleaned that the injection pump's “maximum” capacity is reputed to be 60inHG but the actual restriction measured for a good filter is between 2-5 inHG.

I’ve also have been trying to find a poor-mans alternative to the $200 GM restriction gauge. I would like to be able to measure before and after restriction on my new (coming soon JK) fuel filter. The thought is to find an adapter for the schrader valve fitting that would allow connection of a common ($20) vacuum gauge. So far I haven’t been able to find anything. The fuel line restriction test port looks similar to a R134 high side fitting but not quite the same. Anyone have any ideas?
smile.gif

[hoot]

How about a low pressure inline electric pump to push fuel through the added filters?

[TLA]

westmarine.com has lots of Racor items, including a vacuum gauge that plumbs in line. Racor number is RK11233 for the gauge or 1606B for the kit. If you are using a Racor housing, you should have lots of different ports to hook into. If you just want to know, and have a set of old style A/C Gauges, just hook to the Schraeder valve. I use mine to test fuel pressure on my '97 7.4.

[MaxACL]

hapaschold

Don't know what the flow is back to the tank after the injection pump, but when I go to refill my 115 gal tank in the bed, I can hear a fair amount of flow back into the tank. The flow has to travel two feet to the (low) level of the tank and makes enough noise that I will sometimes have to quit filling up the tank and run to the john. Sorta of like listening to water running and it reminds you of a full bladder...

Mike :eek:

[hapaschold]

thanks again for the help, but any thoughts on these diesel fuel air eliminators out there ?