mixture question--

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mixture question--

Postby jethro » Wed Feb 08, 2017 10:59 pm

This is still something I basically don't understand----
don't understand how the motor controls its mixture that is rich/lean. All I can figure is that the air flow at whatever temp
and flow rate and whatever turbo pressure --- is what it is... depending on the environmental conditions.
The fuel pump and its controls must be just approximately trying to run on some kind of "ramp" generated by several
different springs inside the pump mechanism. Does the pump "know" what the air is doing and have any ability to adjust ?
I remember there is a little (air pressure) line from the intake going into the pump-----

I ask because I had my pump overhauled locally- I have no reason to believe they didn't do a kick-ass job----
It runs great-- I NEVER have seen any smoke (unless I accidently shift up 3 gears instead of 1 :jocolor:
But--- when idling It seems like I can smell a slight fuel smell in the exhaust. No smoke of any color- no water that I can see.
No oil missing, no water missing,-------
(running stock 93 intercooled injectors- 2-nd gen lift pump with the 13 lb spring, 60lb over valve springs, Stock holset turbo
from the 93 (H1C 18mm I think-), big ford intercooler. Boost runs about 1-3 psi in normal traffic. Most Ive seen here in flatland (Fl.) is about 6-7 psi. (in 6-th gear going up an overpass) 95% of the time seems like the engine doesn't even know the truck is back there except in 6 gear. (F-350, 8000 lbs empty) I can definitely FEEL the torque bumping up when I get up into the lower-middle RPM's and the turbo starts doing something.

Could I be a little rich ? How would I know ?
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Re: mixture question--

Postby Rob_O » Thu Feb 09, 2017 9:38 am

The smoke screw on top of the pump adjusts the fuel at idle. You can adjust it up about a turn easily enough and see if that cleans up the exhaust like you want
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Re: mixture question--

Postby Remps » Thu Feb 09, 2017 11:41 pm

All it can make is 6-7 psi? Sounds like a pump issue. Or have you still not floored it yet? :grin:
'90 D250 R/C,727,IC,6x.009's,1/8" bump,fuel psi,straight pipe w/5" stack.
'90 W250 R/C,47rh,K@N,HX35,1/8" bump,2nd gen IC,boost,egt,trans temp.3.07's.
'96 2500 S/C L/B,2wd,NV5600,3.54 L/S,cai,egt,pacbrake,mbrp exhaust,10 plate.
Bring back the Bank of Canada, PRE- 1974.
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Re: mixture question--

Postby 79Powerwagon » Fri Feb 10, 2017 6:38 am

Remps wrote:Or have you still not floored it yet? :grin:



Sometimes going from a powerstroke to a cummins can be a little intimidating... it's ok, we're here for ya. :D

The pump is basically set up how you said, a ' ramp' of fuel determined by governor and fuel pin. Fuel pin movement is dictated by boost pressure. The pump fuels, rpms raise, turbo spools up forcing air into the engine. The air is determined by what the turbo is pushing and what the engine is pulling in.

These engines tend to be a little stinky but you could have a weeping injector or two causing a fuel smell. Your boost pressure should be in upper teens full load.


Btw there are much more talented people here who can explain it better than I can.
1979 Dodge Warlock, I/C 12v, 518, TCS89% Converter, 6x13 injectors, HE351cw, Piston lp
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Re: mixture question--

Postby dpuckett » Wed Feb 15, 2017 10:16 pm

What rpm are you seeing the 6-7psi? If you're stomping it at 1400rpm, boost wont peak like it will when stomping it at 2200.

It sounds like your AFC guide pin may be stuck. These pumps are 25 years old, and sometimes they need more than just a freshening up.

Check lift pump output. Bare minimum is 5psi IIRC. Hungry Diesel sells upgrade kits that work nicely.

Pressure test intake system from turbo to intake. Might have a loose clamp or hole somewhere.

What is your timing set at? For towing, I have had the best luck with 1.4-1.5mm at TDC. Others have had different results
His- 93 W250 club cab LE, auto to Getrag conversion, piston lift pump, 3.54 LSD. 400k+
Hers- 04 QC 4x4. Built auto, Triple Dog, Air Dog. Funny Round truck that aint so quiet.
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Re: mixture question--

Postby jethro » Fri Feb 17, 2017 9:29 pm

Yes Remps--- your guess is correct--- havnt yet floored it yet. I really don't have an easy way to load it. I am waiting for the 500 Mile
mark for the new ring and pinion so I can change the rear end oil. I don't have a D-9 catepeller to pull ---- :-)

The pump has been overhauled and well as all the injectors.
I never drove a powerstroke-- as it was removed before I got the truck. Im sure they make great HP and Torque--- until the next
time they explode. so I am not "spoiled" by a ford engine ! (thankfull I never had that curse)

I may just drive it over to the place that overhauled my pump and see if they have a gizmo that can sniff the exhaust and measure
to see if there is excess fuel--- or maybe they will just take a whiff ...... They are nice folks and may even adjust it for me on the spot
if they don't have to take anything apart.

I have so much torque on tap --- it seems like the only way I CAN load it is stomp it at lower RPM in 5-th or 6-th gear going up an overpass. In 1-st (1 gear above "low") I just let the clutch out without touching the gas pedal--- it just goes. (in "low" at idle- I can
just put it in gear without the clutch--- did that once accidently without even realizing I could do it....)

don't have a working tach yet--- but I can feel the RPM range where the boost is working-- especially in 3-rd and 4-th. It really
scoots. I can roll along about 35 in 5-th gear at idle. Not even lugging- just easeing along. I have tall narrow tires to keep rolling
friction down. I still have the stock H1C turbo that was on the engine from the factory. I have a large straight thru style muffler and a 3 inch SS exhaust. BHAF intake filter. Very quiet at the back. maybe because there is such a light load on the engine? Expected more noise. Quiet as a gasser with a stock muffler.

Thanks-
Tim
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Re: mixture question--

Postby Remps » Sat Feb 18, 2017 12:11 am

I knew it! After you get the diff broken in it"d be good to do a shakedown run and see what it makes for boost, before towing anything with it, for safety's sake. Better to have problems reveal themselves empty instead of towing. The clutch should be able to hold full power with the truck unloaded for safe towing, generally. Consider it a pressure test of your intercooler boots as well. As soon as your h1c wakes up and starts pulling in high gear, (probably 1600-1650 rpm with you mild-ish? pump settings and factory injectors) just hold it to the floor and see what it does. 25 psi would probably put you around low 200's for rwhp, depending on timing. I'd try turning the smoke screw out a few turns as well, nothing can be harmed on the pump by doing so.
'90 D250 R/C,727,IC,6x.009's,1/8" bump,fuel psi,straight pipe w/5" stack.
'90 W250 R/C,47rh,K@N,HX35,1/8" bump,2nd gen IC,boost,egt,trans temp.3.07's.
'96 2500 S/C L/B,2wd,NV5600,3.54 L/S,cai,egt,pacbrake,mbrp exhaust,10 plate.
Bring back the Bank of Canada, PRE- 1974.
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Re: mixture question--

Postby jethro » Sun May 21, 2017 10:52 pm

Remps---
I think im at about 600 miles in the new diff.... but havnt changed oil yet.
I have tried a few times going up overpass ramps in 6 the gear going about 50- and pushing it down about 1/2 way and maybe got 8 psi....
wish we had a mountain round here.....
don't have anything to tow right now....
T
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Re: mixture question--

Postby Remps » Tue May 23, 2017 8:49 pm

If you can idle at 35 in 5th, then 50 is too slow in 6th to really put a load on it. After you get the oil changed, just hold it to the floor from 35-55 mph in 5th, or 55-75 in 6th. Either would get you very close to the same boost as you would towing. Sounds like your afc hasn't seen full travel either, along with your throttle.
'90 D250 R/C,727,IC,6x.009's,1/8" bump,fuel psi,straight pipe w/5" stack.
'90 W250 R/C,47rh,K@N,HX35,1/8" bump,2nd gen IC,boost,egt,trans temp.3.07's.
'96 2500 S/C L/B,2wd,NV5600,3.54 L/S,cai,egt,pacbrake,mbrp exhaust,10 plate.
Bring back the Bank of Canada, PRE- 1974.
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Remps
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