Baseline/Static Fuel pressure

D

DarksideV6

New Member
Joined
Feb 23, 2006
Hi all. I usually try and lurk and search before I post, but this one has me stumped.

My father purchased a lower mileage 87 GN about a year back and had a local turbo buick guy do some basic maintenance and some go-fast goodies.

Long story short, he was complaining to me of a raw fuel smell coming from the car once it was warmed up and also rough cold idle. I went to his house and started poking around. First thing i noticed is the jam nut on the afpr had backed off. I brought a known/working fuel pressure gauge with me so I hooked it up. Turn the key and it primes to 38 psi then drops. Start the car and it's around 53-54psi. Remove the vacuum line and it drops to 51-52psi. I start adjusting it down shooting for 43psi and it will not adjust. It seems like it's baseline is at 51-52psi.

So, my question is. Is this normal to have such a high baseline number?

I'm tracking down the details on mods, but from what I can see and what my father was able to tell me, the car has precision injectors, bigger fuel pump, precision intercooler, kirban afpr, cai, full 3" catless exhaust, caspers voltage booster, unknown chip(asked him to pull the computer and check. Chip has a sticker with two big blue T's on the side visible under the cover).

Any help is appreciated. My apologies for the novel..lol



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Possible kinked or blocked return line is where I would start.
 
or maybe a big ass fuel pump that's overpowering the fuel / return lines?
Wouldn't be the first time a big pump has been blamed for fuel pressure too high and unable to turn down
 
Mine does the same thing for the first 20 minutes or so, then after it has warmed up it drops down to 43 (line off). Mine as an aftermarket pump and hotwire kit. not sure of the pump as it was in the car when i bought it. All new tank and hardware. one of these days I'll get in there and see what pump is in there. my alt is putting out about 14.2 volts then drops to around 13.x when warmed up, I am guessing it is the higher voltage at turn on.

Check your purge canister line for the gas smell. If it has been deleted, make sure there is at least a filter on there to cut the fumes, i put mine back on and still have room to run my K&N air filter.

chip is a turbo tweak chip, get the # off it and call or message Eric with # , he should be able to tell you what mods chip was burnt for, good luck
 
Thanks for the suggestions, guys. I'm going to hopefully look at it some more on Sunday and see what's going on. I'll report back.

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Ended up taking another shot at adjusting the fuel pressure. Let the car get warmed up and it was around 49psi and won't budge any lower. Return lines look good and it definitely has a hot wire kit on it. Purge canister looks good and I cant replicate the raw fuel smell my father complained of. I took the numbers off the chip and emailed them to Eric. Hopefully I hear back from him soon.

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Did you try blowing shop air in the return line to verify it was clear to the tank?
 
Pronto said:
Did you try blowing shop air in the return line to verify it was clear to the tank?
Click to expand...

A little late to the party (sorry i missed this.)

Yes. I used compressed air to the tank. Nothing changed in terms of the fuel pressure and ability to adjust it. I think this pump is just very big and powerful. Maybe too much for the stock return lines? The car seems to be running good and I still can't replicate that raw fuel smell.
 
I also reached out to Eric at TT to see if he had any info on the mods list that accompanied the chip that he burned for the car, but unfortunately never heard back. I have what's on the chip, but was hoping maybe a more extensive mod list would have been provided to him for the chip when it was burnt. Specifically, the type of pump in the car.
 
Did you ever find out what pump is in it?
 
Pronto said:
Did you ever find out what pump is in it?
Click to expand...
I reached out to Eric at TT to see if he had the mod list that accompanied the chip when it was made for the car, but didn't hear back. So, we still don't know for sure what pump is in the car.

Not sure if he would even have that info, but I figured it was worth a try.

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If I don't respond to an email, send me a PM here. I can look it up, but generally people don't always tell me what fuel pump they have.
 
How long ago was the pump replaced? Can't find the receipt?
 
Pronto said:
How long ago was the pump replaced? Can't find the receipt?
Click to expand...
Work was all done in the last two years. Problem is, my father had the work done by another GN guy locally, and the work all seems nice, but he (my old man) wasn't very diligent in getting the details or info on the specific mods.

He wasn't able to get in touch with the person who did the work either. I may try and track him down myself if the mod list he gave to Eric when getting the chip made didn't include the fuel pump info.

I'd hate to drop the tank to figure out what kind of fuel pump is in there..lol

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If it was within 2 years, it's possible the pump is a DW300 which could overwhelm the return line.
 
Is the fuel gauge accurate? Those small ones are not known to be accurate. I like the 2 /1/2 myself. Just a thought
 
SS/GN said:
Is the fuel gauge accurate? Those small ones are not known to be accurate. I like the 2 /1/2 myself. Just a thought
Click to expand...
The FP gauge I'm using is good. Works fine on other cars and shows correct prime pressure on the GN.

Eric got me the info on the chip. Unfortunately, it didn't include the pump info when it was ordered. Did learn that it has a ta49 turbo on it, though.

Pronto, I'm thinking this pump is just overwhelming the return line at this point, as well. I've told my dad he should just let me make the two hour trip to Cottons at this point and maybe they can figure something out. Maybe drill out the return line?

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Anthony P said:
DarksideV6,

another member here, Tori, just went through this issue. please read the thread below. He thought the adj fuel pressure regulator was to blame when he was just another TB owner to get screwed by the installation of a way too oversized fuel pump.

http://www.turbobuick.com/threads/adjusting-bosch-233-regulator.449410/
Click to expand...
Thanks for posting this! It's the exact issue we are having.

It seems like he replaced the pump to fix the issue. Is running a new line the best option or total pump replacement?


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