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DS4 IP rebuild time(mechanical aspect only)

buddy said:
Like Bison said the return fitting regulates housing pressure. If you make it flow more you will get faster flow through the IP as long as your LP is high powered like Bison said. PMDcable.com just started carrying a new Walbro that would do the trick, but Leroy is out of town next month. People that have a real hard time maintaining LP pressure to the IP may actually have a return fitting that is out of tolerance and is flowing too much and LP cant keep pressure up.
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I don't think opening up the IP return niple is gonna flow more back to the tank,all you accomplish is lowering the housing pressure(not good).
All the fuel entering the IP is going trough the TP, and only the spill over at the delivery valve is avalable for return to the housing trough the TP relief valve.

At least,that is my understanding of how it works.
 
I have drilled out a return port and it really did nothing for the return flow but i think the transfer pump was junk.

i have a FASS pump so flow is not a problem. i guess my next trick ie to drill and tap the bottom of the pump housing and put a hose with a solenoid valve trigered by my controler in purge mode.

this may also help with the problem someone stated before about the fuel in the lower part of the pump just kinda staying there. I do see a lot of advance pistons sitcking.
 
Great bump! I just read the whole thread, and going inside the ip is the last frontier for me. I have both a Db2 mechanical and a 1995 ds4 electronic, and I am looking for answers for my relatively high rpm NA 6.5 engine. What is different about 'marine' db2's? Are they regular db2s with opened up passages? Can a regular one be rebuilt to marine specs? Or even better, be rebuilt specifically for my 6.5 NA project? I want good fueling to 4000 rpm, so I figure it will need higher lift pump pressure and maybe more advance. Can the advance curve be adjusted?

Does the ds4 HAVE to be electronically controlled? Or could certain parts be replaced and/or electronic circuits mimicked to make it function without a computer?

I am not afraid of any project, including 'risky' tinkering. Does anyone have a link to rebuilding kits? I will tweek and massage my db2 til the cows come home (or for about as long as it is already going to take to rebuild the long block).
 
I doubt it Les
The tolerances are so small that after machining and hardening the rotors are a hand select fit, that why one can't just swap rotors in IP's
But if one could i think the cost would far outweigh the price of a new rotor head.
But i been wrong before
 
Depends on what part needs more material. I don't remember chrome being that tough. Might have been more Nickel? I worked somewhere that would "chrome" tool shanks that were undersized then regrind to size. The build up depending on thickness varies just a bit. Sometimes it would fail I guess due to bad prep or other issue. It was not always a viable fix.
 
Yeah I didn't even hesitate. Bought it before anyone else had a chance. It covers disassembly and reassembly with torque specs exploded views etc.

Sent from my Studio 5.0s using Tapatalk
 
ak diesel driver said:
Yeah I didn't even hesitate. Bought it before anyone else had a chance. It covers disassembly and reassembly with torque specs exploded views etc.

Sent from my Studio 5.0s using Tapatalk
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I have a print out with exploded views, a parts list and the test bench specs.
Got it send to me free from a diesel shop i deal with.

Yeah,..i get lucky too once in a while ;)
 
ak diesel driver said:
so how come your not rebuilding all those cores you got?
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Cause i ain't worth it..If i do rebuild them then i might have 15 rebuild not bench tested IP's on the shelf and be at least $1500 in the hole.
And who in his right mind is gonna buy an IP without warranty that it may or may not work?
 
is there a place near you that could bench test? Better price for increased volume? Db2 or ds4? you don't have a spare engine on a stand for testing,huh?
 
Will L.;474114[B said:
]is there a place near you that could bench test?[/B] Better price for increased volume? Db2 or ds4? you don't have a spare engine on a stand for testing,huh?
Click to expand...
Place closest by(100+ml) wants $300 a pump just to test it regardless the number of IP's,.the next outfit is 300 ml further and wants $250 same thing.

Ehh..nope,.and i ain't interested to go to the trouble of doing it that way either
 
so I got my book! pretty interesting. If anyone has any ?s I'll try to answer them, I'm reluctant to post pics do to copyright. good book shows flow charts of fuel in different colors for inlet pressure, TP pressure, housing pressure, Injection line pressure, and lube oil.
 
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