Fuel pressure/speed den computer 7730
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Team Owner
Joined: Jul 1999
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From: Orange Park Florida
Fuel pressure/speed den computer 7730
Basic L98 engine with LT1 induction 52mm tbody, 1227730 speed density computer, all new sensors, HEI up top.....modified manifold, obviously.....
so, my gauge says the fuel pressure is only ~30-35 psi and injectors are China made but new rated at 24 lbs........the question is IF the fuel pressure is too lo, as in 30 lbs, IS IT POSSIBLE that the fuel pressure is too LOW and forcing the computer to over compensate and seeming to run too rich??? stumbles, runs rough, really bad on off idle take off, need jack up idle/throttle openings to get it to idle at all and go into gear/automatic without dieing????
I understand fuel pressure should be ~43 some odd PSI, but if too low, whould be computer be trying to compensate too much and cause all the unstable operations, but still start immediately ???
The way it operates, it seems to act as if it's too RICH, but I don't understand that......
watt yawl say????
GENE
so, my gauge says the fuel pressure is only ~30-35 psi and injectors are China made but new rated at 24 lbs........the question is IF the fuel pressure is too lo, as in 30 lbs, IS IT POSSIBLE that the fuel pressure is too LOW and forcing the computer to over compensate and seeming to run too rich??? stumbles, runs rough, really bad on off idle take off, need jack up idle/throttle openings to get it to idle at all and go into gear/automatic without dieing????
I understand fuel pressure should be ~43 some odd PSI, but if too low, whould be computer be trying to compensate too much and cause all the unstable operations, but still start immediately ???
The way it operates, it seems to act as if it's too RICH, but I don't understand that......
watt yawl say????
GENE
Thread Starter
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Well I called the chip man, Alvin Anderson's outfit....PCM of NC......and sure enough, they said the FP needs be at 43 psi.......witch made NO SENSE because it acted like running rich as Bill Gates......
well, guess what, I got the FP up there, and sure enough.......
eliminated about 90% of the running issues, and no longer acts as if it's dumping fuel down the pipes.......
so go figger......
well, guess what, I got the FP up there, and sure enough.......
eliminated about 90% of the running issues, and no longer acts as if it's dumping fuel down the pipes.......
so go figger......
Drifting
Joined: Jun 2018
Posts: 1,678
Likes: 229
From: Michigan
It's because of atomization. The fuel was not completely burning is why it was showing rich. At the higher pressure the fuel is spraying rather than squirting out of the injector.
Last edited by KyleF; Jun 9, 2020 at 02:51 PM.
Thread Starter
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
now for the krazy part, it's a LT1 on an L98 engine, with HEI up top and the speed density 1227730 computer from years ago....now I have an L98 style adjustable regulator, and so I even put on the black painted steel vacuum cap, and found no change, still at ~30 psi.....eh?? so I went back to the adjustable cap and modified it a bit so to be able to adjust it to 43 psi hell or high water.....and sure enuff.......
I even took the fuel filter off the suck side of the pump figgering on a flow issue.....no go.....
so filter goes in tmrw AM.......Floriduh 110% humidity, 90+ temp.......no wanna work out there......
