Fuel pressure too high

1984 t-type

Murphy's Law
Joined
Jul 11, 2010
Well looks im added to the list of people who cant get fuel pressure low enough with stock lines and a DW300 pump. I was wrong you were right lol. Does anybody sell a reasonably priced sending unit with AN fittings ? Im planning on modifying mines since its new anyway but if i can find one for the right price ill just save the hassle.
 
Racetronix has a nice sending unit with AN fittings.

I would save the money and make your own lines. Hell, I could make them for you I'd just need the lengths.

I would save yourself the money and start with replacing the return line first.
 
Im only starting with the -6 return line and i can make that myself no problem, what im looking for is a sending unit with an fittings already installed or ill just mod my sending unit if the price is too high. Racetronix does not show a listing for just their sender
 
What's the lowest it will go?

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I checked Full Throttle first since they are local to me but they don't show a sender only listing either, I tried to call but they have been closed since Friday ill check again tomorrow
 
Im at like 55-58 with the adjustment screw out, i cant give you guys any scanmaster number for blm or anything since i sold my scanmaster to get a G but full throttle was closed Friday so now im waiting on them to open back up, im just assuming thats too high and i need some adjust ability.
 
What's the lowest it will go?

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I heard it won the local limbo contest, so I imagine pretty low ;)

I checked Full Throttle first since they are local to me but they don't show a sender only listing either, I tried to call but they have been closed since Friday ill check again tomorrow

$318 from FT. Make your own lines for $100 for a return setup, and you're good.

link: http://www.fullthrottlespeed.com/ra...o-jic-adapters-for-turbo-buick-gn-t-type.html
 
Im at like 55-58 with the adjustment screw out, i cant give you guys any scanmaster number for blm or anything since i sold my scanmaster to get a G but full throttle was closed Friday so now im waiting on them to open back up, im just assuming thats too high and i need some adjust ability.


IS it a Accufab regulator ?
 
I'd run the base at 55 and call it a day.


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I'd run the base at 55 and call it a day.


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Depending on your pump that may significantly reduce output when you figure the flow numbers with boost included.

For example, look at this Racetronix 340lph pump : http://www.racetronix.biz/itemdesc.asp?ic=RXP340M&eq=&Tp=

If you figure a base pressure of 45psi normally, and he runs 25psi of boost, that would put him at 70psi pressure for the pump under boost. This pump flows about 250lph at 70psi.

If you run the 55psi and add the 25psi of boost, the pump now sees 80psi under boost. The fuel flow for this pump at 80psi goes down to about 200lph.

The point I'm trying to illustrate is that if he is already running close to the max of what this pump can do (I am not saying he is, but perhaps in the future he might be) and you add another 10psi to the pump, your flow rate decreases that much more, which could potentially put him outside the safety range of that pump, and potentially run lean because of it.

Not saying this is what is going to happen, but just trying to show that adding 10psi to the base pressure can have effects that need to be taken into account when making sure your fuel pump can flow enough.

Here is the flow sheet for the DW300: http://www.deatschwerks.com/resources/fuel-pump-tech/dw300-fuel-pump-tech . At 70psi it is around 285-290lph. At 80psi it is more around 260-265lph. That is a drop from about 76gph down to 69gph. May not be incredibly huge, but if he ends up pushing this to the max, that may be the difference between running fine and going so lean he detonates...
 
No but this regulator was on my car before I swapped pumps and went to E85 and I was running my base fp at like 42 then so I figured it wasn't the regulator
 
If you drill the Saginaw fitting on the return line down by the frame next to the steering box,you should be able to lower your idle fuel pressure some. Then set the idle fuel pressure to 55 line off. Every other option will cost money. There's no need to replace the feed line.
 
For what it's worth, I spoke to Full Throttle a little ways back and they said Racetronix does not sell them blank sending units with AN fittings, just with the pumps.
 
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