Baseline/Static Fuel pressure

[Anthony P]

thinking what you have is basically a stock motor with maybe some bolt-ons....

replace the oversized fuel pump with something more appropriate. see post 35 in the linked thread.

any 255 ltr/hr pump like a Walbro 340 or DW200 would be fine. Also, any 215 ltr/hr pump like the Walbro 307 would be OK as well. they cost the same. see post 35 where I list vendors and cost.

have to remember that fuel pump must flow enough fuel at pressure to satisfy engine demand. baseline fp plus max boost psi equals fuel pressure needed at regulator. pump output decreases as fuel pressure increases. starting with a baseline so high, not so good.

replacing a fuel pump is easier and cleaner that buying and installing a braided line and fittings to replace the return line.

 

[DarksideV6]

thinking what you have is basically a stock motor with maybe some bolt-ons....

replace the oversized fuel pump with something more appropriate. see post 35 in the linked thread.

any 255 ltr/hr pump like a Walbro 340 or DW200 would be fine. Also, any 215 ltr/hr pump like the Walbro 307 would be OK as well. they cost the same. see post 35 where I list vendors and cost.

have to remember that fuel pump must flow enough fuel at pressure to satisfy engine demand. baseline fp plus max boost psi equals fuel pressure needed at regulator. pump output decreases as fuel pressure increases. starting with a baseline so high, not so good.

replacing a fuel pump is easier and cleaner that buying and installing a braided line and fittings to replace the return line.

Thanks! Yes. The motor is stock and has a TA49 turbo, 60# injectors, precision IC, TT chip etc. Basically, all the bolt-ons and a slightly larger turbo. Looks like a new pump will be the next step.

I want to see my dad enjoy this car and right now he's not.

This all makes sense. Running a 9 second pump on a 12 second combo isn't a great idea..haha

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[marcus jul]

If you don't have a catalytic converter on you will get gas smells. Mine does this.

 

[ttribejr]

just upgrade the return line and call it a day. I had the same issue with a plane old 255 walbro. I couldn't find any kinks in the return line, but used the 5/16" vapor line as a return and got my fuel pressure from 55 down to mid twenties (lowest).

 

[Ttype6]

Disconnect the flexible return line from the steel line at the frame by the steering box. Allow the return fuel to flow into a bucket while the engine is running. See what the pressure does in this configuration. Drilling the Saginaw fitting on the steel return line that the flexible return line connects to will allow for lower pressure,but probably not enough. This is something that won't harm anything or cost anything. It will tell you what you need to know. Then you can figure out your next move from there.

 

[DarksideV6]

Disconnect the flexible return line from the steel line at the frame by the steering box. Allow the return fuel to flow into a bucket while the engine is running. See what the pressure does in this configuration. Drilling the Saginaw fitting on the steel return line that the flexible return line connects to will allow for lower pressure,but probably not enough. This is something that won't harm anything or cost anything. It will tell you what you need to know. Then you can figure out your next move from there.

Thanks. I will give this a try and see what happens. I'm convinced it's the pump at this point. This should verify that.

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[Anthony P]

you'll want to confirm that a fuel pump hot wire kit was installed when that oversized pump was installed. any fuel pump, whether upgrade or stock replacement, needs constant voltage - there is already a voltage drop of 1 VDC or more over the factory wiring and that wiring is now 30 years old. put a draw on the electrical system like headlights and you may see a greater pressure drop. any one of these hot wire kits would be fine. I'm sure there are others but you get the idea.

http://www.fullthrottlespeed.com/racetronix-buick-hot-wire-harness.html

http://www.casperselectronics.com/cart/index.php?route=product/product&path=8_56&product_id=21

http://www.kirbanperformance.com/product/229/FUEL+PUMP+FEEDER+KIT+#6751.html

 

[DarksideV6]

you'll want to confirm that a fuel pump hot wire kit was installed when that oversized pump was installed. any fuel pump, whether upgrade or stock replacement, needs constant voltage - there is already a voltage drop of 1 VDC or more over the factory wiring and that wiring is now 30 years old. put a draw on the electrical system like headlights and you may see a greater pressure drop. any one of these hot wire kits would be fine. I'm sure there are others but you get the idea.

http://www.fullthrottlespeed.com/racetronix-buick-hot-wire-harness.html

http://www.casperselectronics.com/cart/index.php?route=product/product&path=8_56&product_id=21

http://www.kirbanperformance.com/product/229/FUEL+PUMP+FEEDER+KIT+#6751.html

Yes. The car has a hot wire kit on it, too.

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[Anthony P]

good on the hot wire kit. at least that went correctly. you are the 4th or 5th TB guy this month that I've commented on fuel pressure problems resulting from way oversized fuel pumps in near stock powertrains. that just sucks there are many who were sold pumps, knowingly or unknowingly, capable of 750+bhp to be used on engines making less than 400bhp.

from the linked thread and many others problem solving oversized fuel pumps on ~300 bhp range stock motors...

if you decide to drill the return line, drill the saginaw fitting at the frame crossmember to 9/64 as noted. but I would not bother as it has already been said that process will lower the fuel pressure but not to where it should be. maybe gets lowered to 49-50psig for a baseline. save yourself the effort and look into getting a properly sized fuel pump.

 

[dank GN]

Instead of going a paying cottons why don't you take that money and order the racetroinxs fuel line kit ? I am runing a -8 supply and a -6 return with a walbro 430 with a boost-a-pump with no issues . The kit was pretty simple to install .

 

[DarksideV6]

good on the hot wire kit. at least that went correctly. you are the 4th or 5th TB guy this month that I've commented on fuel pressure problems resulting from way oversized fuel pumps in near stock powertrains. that just sucks there are many who were sold pumps, knowingly or unknowingly, capable of 750+bhp to be used on engines making less than 400bhp.

from the linked thread and many others problem solving oversized fuel pumps on ~300 bhp range stock motors...

if you decide to drill the return line, drill the saginaw fitting at the frame crossmember to 9/64 as noted. but I would not bother as it has already been said that process will lower the fuel pressure but not to where it should be. maybe gets lowered to 49-50psig for a baseline. save yourself the effort and look into getting a properly sized fuel pump.

It seems like overkill. I was surprised the car had 60# injectors on it, too.

Next time I can get to the car, I'm going to disconnect the return line and see how that changes things and go from there. Seems like the pump change, or at least a proper return line, will fix the issue.

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[626gn]

you are the 4th or 5th TB guy this month that I've commented on fuel pressure problems resulting from way oversized fuel pumps in near stock powertrains. that just sucks there are many who were sold pumps, knowingly or unknowingly, capable of 750+bhp to be used on engines making less than 400bhp.

from the linked thread and many others problem solving oversized fuel pumps on ~300 bhp range stock motors...

Could not agree more. Don't know what the fascination is with those who want an oversized pump for simple goals then complain they can't get their fuel pressure down, in some cases even after they were warned

 

[DarksideV6]

Could not agree more. Don't know what the fascination is with those who want an oversized pump for simple goals then complain they can't get their fuel pressure down, in some cases even after they were warned

Just trying to get this fixed for my dad. He's not an Internet research kinda guy and trusted someone locally, who has a few of these cars, to make his a little more stout. No complaints here.

I appreciate everyone's help. I'll update as soon as I get a chance to get over his place.

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[Anthony P]

the following may be obvious but I find myself repeating it more and more...

as you go through the car, you have to confirm that the basic tune is setup properly - TPS setting, IAC counts, verify coilpak/ignition module, plugs look OK?, 160* T-stat with the TT chip?, etc. maybe you've already done this? but many don't and wonder why the car is not performing even after the addition of some bolt-ons.

in that other thread, (http://www.turbobuick.com/threads/adjusting-bosch-233-regulator.449410/), I listed links to tech pages on fuel injectors and step by step instructions for the above on gnttype dot org. In a later post, I added a spreadsheet of the engine parameters as seen via an ODB-1 scan tool or a ScanMaster. Just want to confirm that you've seen this and make time to review it. The same members here shared good knowledge on that other post. Anything is easy when you have the correct tools and knowledge how to do it. Hopefully this will be a fun car for both you and your Dad soon.

 

[626gn]

Just trying to get this fixed for my dad. He's not an Internet research kinda guy and trusted someone locally, who has a few of these cars, to make his a little more stout. No complaints here.

I appreciate everyone's help. I'll update as soon as I get a chance to get over his place.

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Sorry man. My post was not intended for you specifically. It was just a general statement after seeing a rash of FP problems lately. You're in good hands here. Keep at it and you'll get to the bottom of it.

 

[monteperformanc]

On my car even a Walbro 340 was a bit too much for the stock return line. The lowest I could get the FP was about 42. It seems like the fuel system was designed for the stock pump and can't handle much more.

 

[Ttype6]

It was just a general statement after seeing a rash of FP problems lately.

This problem has been going on continually for many years since Nick started selling DW pumps.

 

[626gn]

This problem has been going on continually for many years since Nick started selling DW pumps.

Yes. What I'm saying is lately it's been on an uptick, even more than before.

 

[DarksideV6]

the following may be obvious but I find myself repeating it more and more...

as you go through the car, you have to confirm that the basic tune is setup properly - TPS setting, IAC counts, verify coilpak/ignition module, plugs look OK?, 160* T-stat with the TT chip?, etc. maybe you've already done this? but many don't and wonder why the car is not performing even after the addition of some bolt-ons.

in that other thread, (http://www.turbobuick.com/threads/adjusting-bosch-233-regulator.449410/), I listed links to tech pages on fuel injectors and step by step instructions for the above on gnttype dot org. In a later post, I added a spreadsheet of the engine parameters as seen via an ODB-1 scan tool or a ScanMaster. Just want to confirm that you've seen this and make time to review it. The same members here shared good knowledge on that other post. Anything is easy when you have the correct tools and knowledge how to do it. Hopefully this will be a fun car for both you and your Dad soon.

Thanks, Anthony. I'll be sure we go through everything thoroughly. I pretty much walked into this diagnosis blind with just general knowledge from wrenching on my own performamce cars, but not much specific to the 3.8 turbo. This is all very helpful.

I talked to my dad last night about it all. He seemed a little disappointed in what the guy who worked on the car originally had done, based on the new info.

Ultimately, he is happy there is a fix on the way, though. I'll be going over his place this weekend or the next to sort it all out.

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[DarksideV6]

Sorry man. My post was not intended for you specifically. It was just a general statement after seeing a rash of FP problems lately. You're in good hands here. Keep at it and you'll get to the bottom of it.

No worries. I get it. You tell people "don't do this, you're gonna mess it all up", and they say "OK!". But of course, they go and do it anyways lol.

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