'87 project- next round.

[quickster]

So I got the truck running today. No smoking at all- surprise. The truck runs, but seems to be a problem with the idle and throttle response. When I manually control the throttle it takes at least an inch in travel to get the motor to respond. Like pushing the pedal down halfway before the motor revs. And when you let off the throttle quick the motor dies. I was able to run it while under the hood, but tough when using the pedal. Push down, nothing. a little harder, it revs way up, so you let go of the pedal and it dies. Maybe the pump is gunked up inside? I ran it for about 45 minutes in the driveway, and no change. Wondering if it's time for a pump. If anyone has an idea, let me know.

I added fresh fuel in the mid tank with some cleaner. The fuel gage is pinned above full for front and back tanks. No movement when switching between tanks. I can't remember for sure but I think when they show full like that there is no signal from the senders in the tanks. If bad they would read empty. Correct or?

Any input is greatly appreciated. There are some other problems to correct, but I will go over those tomorrow. Thanks

 

[firehonomichl]

Try a new fuel filter and fill it with standadyne or put hotshot diesel extreme in the tank.

 

[quickster]

did that. Half diesel purge and half fresh fuel. Seems like the IP isn't responding fast enough. When it does and it's racing, you let off the throttle and instead of going to idle it dies.

 

[firehonomichl]

The pump mite need timed or the lift pump is on its way out?

 

[quickster]

The pump might be going. I think it's original to the truck. But only 95k.

 

[firehonomichl]

I got lucky with my 89 7.3 it sat for 5 years and I got it and haven’t really had any issues I had to do a starter and radiator and injector return lines turned the pump up a little and advanced the timing a bit and it runs awesome. Maybe it is just gummed up.

 

[Leroy]

Maybe the pump is out of adjustment.

1) SET BASE TIMING
2) SET THE BASE IDLE /
FUEL METERING SET POINT
3) SET DROOP CALIBRATION
4) RETIME PUMP
5) DRIVE FAST

 

[Leroy]

After looking hard, but never finding a good answer about how to tune the DB pump, I just took one and by trial and error fugured out how to calibrate one while on the truck.



This isn't the same as rebuilding a pump and calibrating it on a machine, the pump needs to at be good and run, but otherwise need to be tuned to match the motor.



This is apparent Dark Knowledge or something, but knowledge is power, if you're a good mechanic, and careful you can tune the DB2 pump quite easily ..




Here's my little guide to the procedure..



Tuning this pump is not so difficult .. it's just a matter of understanding where the adjustment points are, and what they do .

With the above advice, I broke free of my hesitance to make modifications to the pump - but were necessitated by an improperly setup take-off ..

i discovered how to get the best results from tuning and set my truck to BEAST MODE ..

So this is an instructional on how to tune your IP ..

1 Set your timing .. I set mine a hair advanced for testing and back it down incrimentally .. But toward Pass fender Adv, Toward Drv fender Retarded



Pump adjustments are easiest made with fan and shroud out the way for safety and ease of access.



Loosen 2 IP nuts and leave the top on slightly snug, with a large cressent wrench on the dr side pump tang 2/3 of the way back on the pump, just a large aluminum rectangle. Run motor and loosten top nut while holding pump steady with that wrench, dont let go or you'll damage the pump and engine and yourself probably. Find that sweet spot and tighten the top nut down, then the others.



Too retarded a pump smokes, has more bottom end less power poor economy, too advanced pump has no line torque and weak on hills, but good highway power, excess heat and can cause damage, find the middle where makes most power, best economy, response, sound, and it suits your driving style.





2 Set the BASE IDLE / FUEL METERING SET POINT

This is done by turning the large nut riding the Governor Stud with a 1/2 in wrench ..

Towards the Pass Side -

Faster Base Idle , Increased baseline fuel Metering , Quick Throttle Response ..

Toward the Pass Side -

Lower Base Idle , Less Baseline Fuel , Lag in Pedal Response

S

You will have the top cover off at least a dozen times.



Set base idle nut on Gov stud, carefully reinstall mindful of solenoid and not installing wot, you can blow up your motor if you are a butterfingers let someone else do it. And have a phone book handy just in case, but I never had a problem, but BE CAREFUL.

My findings to produce the best power and quick clean throttle response ....

Back out the throttle idle set screw way out, so that the minimum available set point is AT the base idle set inside the Pump at the Idle nut ..

When you have it right, you cannot lower the idle any further at the external throttle idle screw ..

This setting - or near it .. Produces extremely powerful , fast throttle response that is smoother than any other position ..

So back the External Idle Screw out - 10 turns for example

Open the Top Cover and locate the Main Idle / Base Fueling Nut, riding the Governor Stud ..

In most cases you want to Increase it , unless your motor wont idle down as low as you'd like, then decrease it ..

Turn it Pass side - maybe 5 turns with a 1/2 wrench ..

Replace topcover -

Take care to push the metering valve small spring tab towards the back, pull the 1 topcover bold up half way to flush, and slide pump from front to back ..

You can feel the resistance if it catches the tab and bolt it down .. don't let it wander too far back or to the side when installing it or your motor will runaway .

Tighten down topcover and double check test for solonoid engagement put key to run and click with connector at the pump ..

Start Engine - Warning - it might rev WAY up .. just depends on how far you moved the base nut out and your pump ..

First time I did it the base idle was 1,600 rpm .. I set it WAY out just to see it's responses ..

Open and turn the Idle nut down a little at a time, until you have reached your desired base Idle ..

I set mine 800, because of stunning throttle response .. but it's also good for oil pressure.. for my setup it was best all around base idle ..

So you want this nut dictating the base idle, not the external throttle idle screw ..

I set my base internally at 800 and added a tiny bump for sound to maybe 810 rpms base idle ..

This results in Incredible Power ..

Be Prepared to take that topcover off 10 times (easy) to get it just right ..

3 DROOP

This is what the Governor Guide Stud controls

It's not so much a base idle adjustment though it has a super small effect on it ..

Do work in tandem with the Base idle Nut for absolute final touches .. BUT

Basicly Get the Base Idle / Fuel right , then set your Droop ..

Droop is how far down your engine will idle in gear, below non load nuetural idle ..

Like if you put it in first and no throttle and light and or light braking RPM's

It will drop up to a Few hundred RPM When you drop it into gear ..

This is where the Gov Guide Stud comes into play ..

Unlock the 1/2 in nut with a wrench, and turn the allen Hex head in to increase droop,

and Turn it out to decrease droop ..

Run, and check for too low or high load after shifting and stable return to baseline idle.



RETIME PUMP and ride !

 

[quickster]

I'm going to have to mess with the timing a bit. Probably all gummed up inside. I ran a jumper from hot to the fuel shutoff valve and got no clicking. After I rapped it a few times with a wrench it started to click. Inside of the pump must need to un goo.
In the first post I mentioned I'm not getting any reading from the fuel gauges, stuck way above full. Sound like no power to sending units, bad ground somewhere???

 

[quickster]

Thanks Leroy. I never messed with the internals yet.But I have a core pump in the garage and tomorrow I'm going to give it a look. Thanks for the insight.

 

[Leroy]

Sure thing

 

[IDIBRONCO]

After looking hard, but never finding a good answer about how to tune the DB pump, I just took one and by trial and error fugured out how to calibrate one while on the truck.

Wes has a thread about tuning these pumps.

 

[quickster]

I looked around and found a few threads on tuning the pump. Lots of pages, but I need some pics to comprehend what I need to do. I took a few pics of a pump I took out of my 7.3. The large nut I'm pointing with the pencil is the governor nut? And the bolt on the linkage is the idle, correct? Does anyone have a link saved or know the name of the thread with pics I can look at? Or if there are any pump schematics tom be found. I looked but can't find anything that is marked out enough. Thanks

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[Thewespaul]

Couple things that are of concern with those adjustments, when these pumps are built there is an angle of workable throttle movement that are allowable for our minmax governors. If you adjust it too aggressively, and have to back out the external idle screw a lot to account for it, the governor can literally drop off the throttle shaft. This will ring the pump to wide open throttle and nothing short of cutting airflow or the engine grenading will keep the engine from accelerating. The other thing is I would absolutely never recommend adjusting timing while running the engine, very easy way to make a paper weight out of the pump. Running the pump without the flange bolts tight puts all the thrust load on the input shaft, which on a stock pump is only counteracted by a very weak wave washer, which is the only think keeping the transfer blades from pushing into the housing and sending metal through the pump and injectors. Just take the time to shut the truck off and make small adjustments until the timing is where you want it to be.

 

[chillman88]

From what I've seen of Wes' posts, sounds like maybe the metering valve is sticking badly? I don't remember where it is, maybe top left inside the housing?

I'd see if you can fill the whole thing with ATF while rotating the input shaft on the front to get it through the whole thing, then plug the ports and let it sit a couple days and see if it will free it up.