fuel pressure
- Thread starter gunnie
- Start date
icanfixall
Official GMM hand model
With that much extra pressure you may have to adjust your timing some. I remember Ken running a 6.9 and had some high fuel pressure to the injection pump. He said that required a change in the timing but I don't recall why. Give it a shot and post back what you find. Plenty of interest here.
Diesel JD
Full Access Member
I remember Agenem saying that anything above 8 psi may effect the timing. Sure it could work if you had a tool for timing the truck and could find out how much it influenced timing, and then move the injection timing back into the safe range at all rpm. Its a cool project, but it would be a lot of work, a pump that puts out the correct amounts of pressure from 4-7 or 4-8 psi would be preferrable or a pressure regulator to keep it in the 4-8 psi range.
Diesel JD
Full Access Member
Not sure I really understand myself..or I would. I got that info from Mel, who works real closely with a stanadyne dealer on the Moose Pump project and has put in a lot of time with a timing meter himself. I do know that when you ahve the cold timing advance on, it advances the timing by restricting fuel flow, and when I have had a lot of air in the system or a very plugged filter I start hearing a harsher clatter(advanced timing) for the same reason. I'm going to guess more fuel flow would retard the timing a bit. I don't know that for a fact. Retarded timing won't hurt the engine unless its really extreme(and maybe not even then) but you'll get very weak performance, lots of blue/white smoke and it may be very hard to start, poor fuel economy as well. Also, that much pressure may damage something on the inlet side of the injection pump...I'm really not 100% sure. Its a good experiment but you're definitely in uncharted territory. The safe bet is get a pressure regulator if you like that pump and set it to 6-8 psi, you'll be good for sure then.
MUDKICKR
Full Access Member
i hope i can explain it a little, on my mustang i put an adjstable fuel pressure reg. on it and set it at 42 psi(factory is 38) its a 96 mustang fuel injected. since the fuel pressure is higher, more fuel is pushed into the cyl then if it was at factory specs. the fuel injector is staying open the same time frame but its letting more fuel in. just like a turbo, when you add a turbo you dont add a camshaft to hold the valves open longer for more air, the turbo pushes more air into the cyl through the same valve that is open the same time. after saying that, the more fuel you give a diesel the more power it gives it , if you give it more fuel pressure it pushes fuel faster to ip, then it pushes fuel faster to the injectors, which in turn on a diesel makes the timing off(since the fuel is going through the injector sooner then factory specs).
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so i should hear more clatter just like fast idle? the reason i'm asking is my holley red (3 yrs old) was making a growling noise, so i thought get it changed before it quits. i bought an after market pump which was supposed to be same as holley red after i installed it just for kicks and grins i put a fuel pressure guage on it between the fuel pump and the fuel filter it checks 12 lbs. i don't have a pressure regulator or i would just install that. whats the downside of running it this way if i drive it normally?
MUDKICKR
Full Access Member
id buy a holley red fuel pump, return the other fuel pump and go with it that way, it lasted you 3 years and didnt give you any problems
Ironman03R
Full Access Member
I had a question about this awhile back, no one really could explain how the pressure affects timing, but I found some info on my own. The lift pump is supplying the transfer pump in the IP, the transfer pump has a built in "bleed off" for high pressure. So my thought of more supply pressure=higher output is not correct. The only thing you will get outta a higher pressure lift pump is a change in the pump timing curve. Will it change preformance? You bet it will, but for better or worse I dont know, I have not had time to work on that yet. I'm still workin on my special injectors.
redneckaggie
rebel w/o a cause
i'm also curious as to this because my electric is leaking fuel around the pump and I have the option to get a 15 lb 150 gph pump that my friend bought and didn't install but i it will hurt the truck i sure don't want to do it maybe we could get mel in here to expain it because if it just advances or retards the timing then i can reset that
