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94 chevy ds4 converted to db2, problems,,,

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all, I have a 94 k3500 with a manual trans, last year converted the ds4 to a db2-4911. cruise control is know working, really like it except,,,,

I get a low rpm light load surge all the time, 4th gear 30 mph around town,,,,,

I didn't change any of the lift pump on the 94 ,, I don't have a fuel pressure gauge, not sure best way to do that,,,

I hear the lift pump running on the frame rail,,,
do I have to much fuel pressure, do I need to change something, recommend me a fuel pressure gauge setup,,,, thanks
 
while holding throttle pedal in one place cruising thru town, 30 mph fourth gear, the engine surges up and down in rpms, making the truck start to buck or jerk, if I hit the throttle and give a little more throttle and let off it will go away for a while, I ordered your fuel pressure tap bolt yesterday and a gauge, will get it installed asap, when I installed the db2 I just made the marks on engine and pump lined up didn't advance the pump at all,,,,
 
Was IP fresh?
I don't know but seems like 4th gear at 30mph is very low speed, are you luging the engine? does it happen if you are at 50mph in 4th? I don't have any real experience with the manual trans.
 
installed fuel pressure gauge today,,,

6 psi idleing at 1200 rpm

4 psi cruising 55 in 5th gear

1 psi hard aceleration in 3rd or 4th gear,,,

at 35 mph in 4th gear in town the motor accelerates easily, doesnt seemed lugged down at all

are these pressures good , bad, or ? never had the tank down to look at the sock, newer delco electric lift pump, new fuel filter,,,

thoughts
 
Those PSI's will make the truck run OK, but it is detuned so to speak.
You see a big improvment if you can get 9-12 PSI at the IP at idle.
Check my Fuel Delivery page on my site for the Walbro FRC10
 
Burning oil said:
Those PSI's will make the truck run OK, but it is detuned so to speak.
You see a big improvment if you can get 9-12 PSI at the IP at idle.
Check my Fuel Delivery page on my site for the Walbro FRC10
Click to expand...

That would be just a little too much psi for the DB2-- a max of 7-8 psi is recommended for the DB pumps..

What LP did you install, stock style 93 would be the best for a stock type..

And play with the timing some, very small amount of movements go a long way..
 
i put a stock ac delco electric unit on the frame rail where the factory one was installled




sctrailrider said:
That would be just a little too much psi for the DB2-- a max of 7-8 psi is recommended for the DB pumps..

What LP did you install, stock style 93 would be the best for a stock type..

And play with the timing some, very small amount of movements go a long way..
Click to expand...
 
I just went through this with my truck. No air in the fuel, good psi from the lift pump. I checked timing and timing was right on, I even removed the water pump to inspect timing. I found that my injection pump was nit updated when it was rebuild a year and a half ago. I pulled it and had it rebuild, and now the injection pump is good. My truck would surge at any cruising speed or coasting down hill. My trucks with the 5 speed db4 or db2 does not like 4th gear at 30mph they are lugging pretty good.
 
What is rpm at 30 mph / 4th gear.

Not to the problem, but 1200 rpm idle with a manual trans? Seems a little high, idk.
 
1200 is a high idle for winter time, doent have anything to do with the problem though, I have had the idle set at 700 also,,,
 
turned the idle down to 800, 1650 rpm at 30-35,

also loosened up the tension on the turbo master spring,,,

will drive later and see,,,
 
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