nosing over

jambbii

jambbii

milk
Joined
Aug 10, 2006
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Well I have been doing some backroads testing and my truck seems to be nosing over past 3200 rpm, once shifted under that its fine and pull good. Its not even like its hitting the govenor either just a real sudden decline. The smoke doesn't clear either when this happends. Not sure if I am running out of fuel or what. I have benched 913 pump that flows quite a bit. This problem really didnt start to happen until I switched my 370s to 435s and it used to pull past 4grand. My truck was dumping some major smoke so I backed off the plate to about the halfway mark. Smoke clears more but is still present. My mods besides the injectors and pump are 0 plate, 35/40 over an Ht3b and my timing is at 24 degrees. I was thinking possibly my fuel system is past its limits. Any thoughts?
 
That is weird.. If you have black smoke, then you still have fuel. Does it feel more powerful withthe 435's ? Is the popo pressure on the 435's the same as the 370's? If not you either have more or less timimg than before.
 
Yeah its more powerful, as far as the pop pressure I am not sure, all I know is that my old 370s where not matched at all.
 
You tried pulling some timimg out or putting some in to see if that has any effect?
 
Timbeaux38 said:
You tried pulling some timimg out or putting some in to see if that has any effect?
Click to expand...

I backed off some timing and no effect. I am going to do some more testing when time permits.

Smokem, I dont have a gauge so I guess that is nex on the to do list:aiwebs_032:
 
Hey Josh

Please give me more info about 435 injectors?
Who made them?
Are they 370 based?
Are there any performance gains?
How about smoke?
How about egt?
How much they cost?


Do you reccomend replace 370 injectors with 435?
 
The 435's flow 38lpm and the 215's flow 38lpm now the 435 has a .018" hole and the 215 has a .010". How can they flow the same rate of fuel if a 370 has a .012 and flows 54lpm?
 
Great. Thanks for the info due to the fact that I'm looking for something better than the 370 without having to change pistons to make them efficient.
 
Well I didnt get a fuel pressure gauge yet...but I took it to the track and it pull real strong though 1st and 2nd and I can feel it slowing down after that. Is my stock fuel system not up to par?
 
For racing, having a "supply side" fuel pressure gauge is very important for diagnosing problems.

BUT...

Normally supply problems when drag racing are worse at the starting line than the finish line. Acceleration hampers fuel delivery.

How's your boost doing? Any big exhaust leaks or intercooler leaks?
 
if it is still smoking, then it is still getting some pretty good fuel.

Did your boost drop any?? If it did, then that would be a sign of fuel problems.
 
McRat said:
For racing, having a "supply side" fuel pressure gauge is very important for diagnosing problems.

BUT...

Normally supply problems when drag racing are worse at the starting line than the finish line. Acceleration hampers fuel delivery.

How's your boost doing? Any big exhaust leaks or intercooler leaks?
Click to expand...

Well my boost is fine. It holds 60 no prob. It doesnt drop when it starts to nose over, it just stops pulling hard at the top end. I dont have any exhaust or intercooler leaks (I have tested everything before) I am not sure if the stock fuel system is up to par. I have been searching and I have read mixed opinions on what a stock 12v pump can dish out.

Josh
 
jambbii said:
Well my boost is fine. It holds 60 no prob. It doesnt drop when it starts to nose over, it just stops pulling hard at the top end. I dont have any exhaust or intercooler leaks (I have tested everything before) I am not sure if the stock fuel system is up to par. I have been searching and I have read mixed opinions on what a stock 12v pump can dish out.

Josh
Click to expand...

I'm certainly no expert on 12v pump output. But it is RPM driven. Unless there is a restriction in the system, it should have the same output at all RPM's, and normally your engine will want less fuel after the HP peak. If it is smoking hard up high, and you have air available, the only thing I could think of would be a lack of timing. More boost likes more timing, and a stock charger will lose boost as you rev, so the ideal timing is different with more boost.

BUT. I'm basing this on dyno sessions programming Duramaxes, which has a different injector design, and does not even smoke up high. It wants timing up top if there's air. It doesn't if there is no left over air.
 
Definity check your fuel pressure. I run a 12v in quick diesel useing a aeromotive pusher pump equal to a holley black. The truck runs .4 to .5 tens slower without the pump turned on. It still smokes too, but not as much as when turned on. Also check the screen filter thats in the tank on the bottom of the module. Mine looked fair to okay but a new screen made a difference. Set up a fuel guage with a long hose so you can put it in the cab and view it at WOT. Jim
 
Well I got a fuel pressure gauge hooked up today. Fuel pressure is normal until I put my foot into it. At half throttle my fp is about 5lbs and if I floor it at any time it drops to 0. I am hopefully getting a new lp tomorrow for free.

Jim, how do you have your pusher pump setup (ie location etc)?


Thanks,

Josh
 
Josh, I'll explain how I set mine up but this might not be the best for you or anyone else. My truck is 2wd so I don't do anything off road. I mounted a 90 degree bulkhead on the bottom of my stock tank, centered and at the rear. Mounted the pump on the outboard side of the frame rail. The pump can be mounted where ever you want. I tried to keep the pump as low as the bottom of the tank. I also wanted to draw off the bottom of the tank instead of going threw the top like the stock system does figuring that would put less strain on the pusher pump. I made a Y type fuel block, put that in the feed line along the frame rail before it goes upward to the fuel heater. Put a one-way valve in the stock fuel line before the Y-block so the pump wouldn't push fuel into that line. I don't use the pump unless I'm drag racing, testing something,etc. All that being said there are probably better ways to set it up. Jim
 
Thanks for the info. I am going to see what a new lift pump improves but I am thinking I may need more fuel eventually. I have a -6 1 way valve that I was thinking of using but I am not sure I want to tap into the tank just yet.
 
DId you clean the prefilter ???

and are your hoses good if they are original you could be sucking air at the high end
 
moneymaker, yeah all that good stuff is clean. I just cleaned the screan and put a new filter on. All my lines are new also.
 
well the only other thing is maybe you are out running your lift pump.
had a problem like that back in the day when i did a lot of street racing (gas motors) high rpm floating the fuel pump ( could not keep up )
 
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