:confused:effect of pump timing? Help!

[Archive]

I've read a fair bit on pump timing and benefits. I recently had my pump timed to about 1. 35/36 mm. (was found to be set at 1. 20mm before adjustment) Prior to this I had some blue haze on startup for a couple minutes. When warmed up it virtually dissapeared. On WOT I had a darker grey/light black haze with nothing noticable on normal gradual throttleup. Since pump timed most all of the above smoke is nearly gone, however i had a noticeable loss of about 2 lbs boost. I tweaked up the star wheel from 12 oclock to about 1:30, adusted the AFC diaghram from about 1:00 to 2:30 and a very small touch on full load fuel. (it is still not bottomed out on the restraining collar,(about another 1/4 turn left. ) This brought my boost back to about 20 psi. ( was about 21 at WOT). Currently i have very little smoke throughout the range. Ex. temp is max 750ish* empty @2450 in OD. I thought that the pump time should have allowed me to reduce fueling and still have equivalent boost/power??? Am I missing something here or have I overlooked an issue?? Should the pump timing improve mileage. (it cant if i have to 'up the fuel' to regain boost/power).
Any ideas, suggestions, or other thoughts fella's. I'm stumped. I did not really want to crank up the fuel and loose mileage. Before the pump time i was getting about 19mpg empty around town. Havent check it since change as I'm still burning a tank to do calculation. Will advise ASAP on new mpg.
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93. 5 D250 4X4,HD Spring Pkg, Rancho 7000's, Rear Swaybar, Dual Shock Front Stabilizer, BD Injectors, 3" Mandrel
bent exhaust, 16cm 'Hot End', Modest Pump Tweaks/Timed, K&N Air, Isspro Pyro,Tach,transmission Temp, Auto Meter Oil Filled
Boost Ga. , 3:54's, 4 Speed Auto, Clubcab, Aftermarket Reclining Buckets w/ctr Drop Down seat/console, Black over Silver, 21psi,
285-75R-16's,American Racing Clear Coat Mags, Amsoil 15W-40HD Marine, 12,000 lb. Warn Winch, KC Spots.
97,000 Kms.

[This message has been edited by BushWakr (edited 10-14-2000). ]

[This message has been edited by BushWakr (edited 10-14-2000). ]

[This message has been edited by BushWakr (edited 10-14-2000). ]

[This message has been edited by BushWakr (edited 10-14-2000). ]

[This message has been edited by BushWakr (edited 10-14-2000). ]

[This message has been edited by BushWakr (edited 10-14-2000). ]

[This message has been edited by BushWakr (edited 10-14-2000). ]

 

[Archive]

How did they determine TDC? If they used the timing pin and didn't check it for accuracy, your timing isn't correct.

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90 W250, 5-speed, isspro gauges, 16 cm2, K&N, Borgeson shaft, JRE 3" exhaust

 

[Archive]

Thanks Matt,, it was timed using the timing pin. When it was done a major amount of effort was put in to come as close to accurate as possible with the 'pin'. Once done the pump was timed. When finished the mechanic said that " the pin slips in smoothly at 1. 36mm and tightens up at 1. 40mm
This should have a setting of very close to 1. 36/1. 37mm taking into account variance. Is this really that far out/significant to impact overall boost??? I have heard that Piers at BD generally set pumps to about 1. 40mm so mine seems to be inside the range so to speak. What do you guys think??


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93. 5 D250 4X4,HD Spring Pkg, Rancho 7000's, Rear Swaybar, Dual Shock Front Stabilizer, BD Injectors, 3" Mandrel
bent exhaust, 16cm 'Hot End', Modest Pump Tweaks/Timed, K&N Air, Isspro Pyro,Tach,transmission Temp, Auto Meter Oil Filled
Boost Ga. , 3:54's, 4 Speed Auto, Clubcab, Aftermarket Reclining Buckets w/ctr Drop Down seat/console, Black over Silver, 21psi,
285-75R-16's,American Racing Clear Coat Mags, Amsoil 15W-40HD Marine, 12,000 lb. Warn Winch, KC Spots.
97,000 Kms.

 

[Archive]

You say you turned the diaphram from 1:00 too 2:30, but where was it to start with. When you rotate the diaphram you change fueling. Pull your afc cover back off, lift out the diaphram and look at it, you need to put it back so that the most inward part goes towards the front of the engine. If you look down the hole while the diaphram is out, then move the throttle linkage, you will see a little pin pop out. That pin rides along the shaft thats attached to the diaphram, & the quicker it gets to the center of the shaft is the spot where you'll have the most fuel delivery. Don't forget to take a slim screw driver and push the pin back into place before you install the diaphram.

 

[Archive]

Hello Piers!
I should have been more specific in my info. I'll learn.
In response to your note, The diaghram was marked and set at 3:00 (now moved back very near 12:00) the star wheel was marked and at 12:00 which was 'stock' I understand. In fact your shop did some tiny adjustments about 5 1/2 years ago when exhaust was done and marked everything. I have now moved the star wheel to about 2:30 as I said. I also see nice clear 'witness marks' indicating the pin is moving up and down properly. In fact there is a tiny bit of lube on the 'cone' which shows the travel rather nicely.
So presently I have near stock on the diaphram, 2:30 on the star wheel,anaroid screw backed out about 1/2 turn to reduce early smoke, and the 'full load' screw about 1/3 to 1/2 turn away from lock collar.
Does this clarify?
Thanks in advance.
Bushwakr

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93. 5 D250 4X4,HD Spring Pkg, Rancho 7000's, Rear Swaybar, Dual Shock Front Stabilizer, BD Injectors, 3" Mandrel
bent exhaust, 16cm 'Hot End', Modest Pump Tweaks/Timed, K&N Air, Isspro Pyro,Tach,transmission Temp, Auto Meter Oil Filled
Boost Ga. , 3:54's, 4 Speed Auto, Clubcab, Aftermarket Reclining Buckets w/ctr Drop Down seat/console, Black over Silver, 21psi,
285-75R-16's,American Racing Clear Coat Mags, Amsoil 15W-40HD Marine, 12,000 lb. Warn Winch, KC Spots.
97,000 Kms.

 

[Archive]

I should've told you to check something. When you set the timing on a VE pump, you have to bend the fuel line a little to get at the back nut. If the tech did'nt bend the line back into place the throttle linkage hits it, rather that the high idle screw. That would explain your loss of boost/fueling as you are no longer getting full throttle.

 

[Archive]

Piers,
I watched carefully when the pump timing was done and the fuel line did not need to be bent or moved. They used a very strange shaped wrench and also a socket with a couple universal joints to loosen the pump bolts.
I have checked the throttle travel and it looks ok. I do need to adjust he linkage a bit as it 'connecting piece' seems a bit long now. I notice that the moment any pressure is placed on the pedal I get an increase in RPM. Its pretty close though and not much adjustment will be needed. I'm not sure were to go from here.

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93. 5 D250 4X4,HD Spring Pkg, Rancho 7000's, Rear Swaybar, Dual Shock Front Stabilizer, BD Injectors, 3" Mandrel
bent exhaust, 16cm 'Hot End', Modest Pump Tweaks/Timed, K&N Air, Isspro Pyro,Tach,transmission Temp, Auto Meter Oil Filled
Boost Ga. , 3:54's, 4 Speed Auto, Clubcab, Aftermarket Reclining Buckets w/ctr Drop Down seat/console, Black over Silver, 21psi,
285-75R-16's,American Racing Clear Coat Mags, Amsoil 15W-40HD Marine, 12,000 lb. Warn Winch, KC Spots.
97,000 Kms.