THD fuel pin install on stock pump

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THD fuel pin install on stock pump

Postby ggreenall90 » Mon Aug 07, 2017 1:39 pm

I installed THD's fuel pin in my stock injection pump and now when I shift from 3rd to 4th the truck will lug. Pump is completely stock other than the fuel pin and its a 5-spd getrag. Do I need to mess with the star wheel? Don't wanna turn the pump up at all.
fuel screw!!!!
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Re: THD fuel pin install on stock pump

Postby matthewh » Mon Aug 07, 2017 4:11 pm

I didn't when I installed the same fuel pin, and my pump is stock as well. I've got the same trans as you, though I've got 4.10's and duals.
Did you remove the plastic washer and bolt the pin right to the diaphragm? Or the little brass tube broken or loose where it bolts to the pump top? Did you face the ramp towards the front of the truck?
Just throwing out ideas,
'93 W350 5spd Getrag, 4.10 gears, 83k miles and counting, Mods: LPPP AKA Ma Dually
'54 Dodge M37 6.2/700R4/205, 5.89 gears, WC rear axle
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Re: THD fuel pin install on stock pump

Postby ellis93 » Mon Aug 07, 2017 6:08 pm

I'd drop the star wheel a turn and see if it helps. I installed an M&H pin with factory settings and my truck bogged like that. Moving the star wheel down helped.
93 D250 ,5 speed,4.11s,k&n autometer tach pyro trans boost guages,GDS 60mm h1c 14cm,honed 5x10,hplp/reg,1/8 timing,M+H M2 fuel pin, tims cooler tubz
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Re: THD fuel pin install on stock pump

Postby spencerdiesel » Wed Aug 09, 2017 8:02 pm

Best pin there is in my opinion :)
1992 W250, 5 speed, 4.10, Ext. cab Ext. bed, 12.5k winch, 75 gal. fuel tank


Fuel: THD 6x10 VCO sticks, THD 12 psi piston pump, THD fuel pin, 366 spring, fuel screw 2 turns in, timing to the head/ >1/4”
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Re: THD fuel pin install on stock pump

Postby odee » Thu Aug 24, 2017 4:39 am

greenall90 did you make any headway on the fuel pin install? I just done the same pin with the same issue. My topend power is way better than before bottom end I have lost. Haven't had any time to do any adjustment yet or any more reading.
fuel screw!!!!
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Re: THD fuel pin install on stock pump

Postby Remps » Thu Aug 24, 2017 5:29 am

The ramp on that pin is more conservative on the bottom, with more fuel available on the top end. This allows more tunability with aggressive fuel screw setting and/or large injectors. On a stock pump and injectors you will definitely have to crank the smoke screw down some so the pin is at the same starting point as stock. I'd start with about 3 turns in on the smoke screw and see how it goes. Two mini flat screwdrivers will work to wiggle that tamper cover off the smoke screw, and it can be re-installed afterward if you want it to look stock. Smokescrew adjusts pre-boost fuel, starwheel adjusts boost/fuel ratio, so adjust smokescrew for off-idle response/pre-boost power, then adjust starwheel if necessary if it still feels weak accelerating with boost.
'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.
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Re: THD fuel pin install on stock pump

Postby Richie O » Thu Aug 24, 2017 8:37 am

If I back off the smoke screw on my M+H fuel pin on my 93 with 6X16's it will stall trying to take off. For sure, crank down the smoke screw. I had to find a happy medium with my big injectors. To much and I got an eclipse at every intersection even trying to be careful. :D
1989 W250 727, 3.07 L/S, S300, P/S Intercooler, Stans exaust, Pump adjustments, 127k miles,297 hp
1993 W250 extended cab, rag, 4.10 l/s, 6x16's, HTT 62/71/14 piston l/p, Isspro EV series tach, fuel pressure, boost, oil pres, water temp, volt, pryo, 132k/ 301 hp
1992 W250 with NV4500, 3.54's, 16cm 60mm GDS H1C, ground stock cone, Isspro tach, pryo, boost, fuel pressure, slow, rusty, dented,180k
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