Fuel Pressure under boost

[Sinisturbo]

My car will not incease fuel pressure under boost. The car is completely stock 87 Turbo T.
I have 40psi fuel pressure at idle with the vacum hose off. With it connected at idle fuel pressure is 34
Under 10 lbs of boost (analog gauge) the fuel pressure tops out at 40?
I tested the regulator with the car idling, hose off 40psi. I injected 20psi of air into regulator port from my air compressor and the fuel pressure gauge goes up to 60psi. regulator is good.
The only thing left would be the fuel pump not keeping up with demand?
I have not purchased a scanmaster yet. I know I need to!

Any feedback would be helpful.

 

[ikle]

When is the last time you changed your fuel filter ? Your problem could be a voltage problem ,a restriction problem clogged fuel filter or your pump is going out. First I would buy a Scanmaster and change your fuel filter, then check the voltage at the pump, then see what your voltage is with the Scanmaster to make sure your alternator isn't going out. If all checks out it might be time for a new pump.

 

[3.8L V-8 eater]

Start the car and loosen the nut on the regulator..While watching the gauge turn up the fuel pressure slowly...Should go all the way to 100lbs if it's short of 100lbs and the needle just flutters and won't go no higher you have a bad fuel pump...

 

[Turbotre]

Start the car and loosen the nut on the regulator..While watching the gauge turn up the fuel pressure slowly...Should go all the way to 100lbs if it's short of 100lbs and the needle just flutters and won't go no higher you have a bad fuel pump...

He says his car is completely stock,where did you read that he had an adjustable fpr?

 

[jopaustu]

When I got my T, there was a heap of parts with the car.. I believe there is a strainer that sits in the tank. I still have it in the box. I replaced the inline filter before I added fuel and started car (barn find), and have had no issues with fuel pressure... this strainer may be from 70 gsx (some of the parts with car were)... Can any one confirm if there is a strainer in the fuel tank?. Maybe this will help

 

[Sinisturbo]

When is the last time you changed your fuel filter ? Your problem could be a voltage problem ,a restriction problem clogged fuel filter or your pump is going out. First I would buy a Scanmaster and change your fuel filter, then check the voltage at the pump, then see what your voltage is with the Scanmaster to make sure your alternator isn't going out. If all checks out it might be time for a new pump.

The fuel filter was replaced about a year ago, but the car did sit for about 5 years prior to that. I may replace the filter, then hot wire the pump.
The fuel regulator is the stock unit 233.
thnaks

 

[ikle]

The fuel filter was replaced about a year ago, but the car did sit for about 5 years prior to that. I may replace the filter, then hot wire the pump.
The fuel regulator is the stock unit 233.
thnaks

Updating your fuel system ( adjustable fuel pressure regulator,fuel pressure gauge,Hotwire kit and fuel pump $300 ) should be your first mod along with a ScanMaster ( $250 ). Make sure you get a fuel pressure gauge ( under $100 )that you can temporally mount under the drivers side wiper arm so you can see if your FP rises 1:1 with the boost you are running. Then since your car sat for 5 years and has the stock injectors you should consider an injector/chip combo upgrade from Eric at Turbo Tweak, 42's ( $290 )would get it done. Your MAF sensor could be bad too, but without a ScanMaster you will be chasing your tail. If you are unfamiliar with Turbo Buicks there might be a member in your area that would be willing to give you a hand. You can find all of these parts from anyone of our awesome supporting vendors.

 

[Ttype6]

Updating your fuel system ( adjustable fuel pressure regulator,fuel pressure gauge,Hotwire kit and fuel pump $300 ) should be your first mod along with a ScanMaster ( $250 ). Make sure you get a fuel pressure gauge ( under $100 )that you can temporally mount under the drivers side wiper arm so you can see if your FP rises 1:1 with the boost you are running. Then since your car sat for 5 years and has the stock injectors you should consider an injector/chip combo upgrade from Eric at Turbo Tweak, 42's ( $290 )would get it done. Your MAF sensor could be bad too, but without a ScanMaster you will be chasing your tail. If you are unfamiliar with Turbo Buicks there might be a member in your area that would be willing to give you a hand. You can find all of these parts from anyone of our awesome supporting vendors.

How do the injectors,chip,MAF and Scanmaster effect fuel pressure?

 

[Ttype6]

The fuel filter was replaced about a year ago, but the car did sit for about 5 years prior to that. I may replace the filter, then hot wire the pump.
The fuel regulator is the stock unit 233.
thnaks

Perhaps,since the car sat,there's some crap in the filter. Use only AC Delco.
You don't want to throw parts at it.
You have a fuel delivery problem and voltage might end up being the cause,but you won't need a hot wire to fix it. That's something you can add after we fix it.

Replace the filter and see what happens.

 

[ikle]

How do the injectors,chip,MAF and Scanmaster effect fuel pressure?

Well the ScanMaster will be able to tell if you have a voltage drop under WOT, low voltage = low pressure. Also I suggested that since the car sat for 5 years and the injectors are original he might want to upgrade them after the fuel pressure issue is solved, so it would be a good idea to uprade the chip at the same time. With the MAF I was giving him an example on how important the ScanMaster is when trying to solve issues on these cars.

 

[Ttype6]

Well the ScanMaster will be able to tell if you have a voltage drop under WOT, low voltage = low pressure. Also I suggested that since the car sat for 5 years and the injectors are original he might want to upgrade them after the fuel pressure issue is solved, so it would be a good idea to uprade the chip at the same time. With the MAF I was giving him an example on how important the ScanMaster is when trying to solve issues on these cars.

The Scanmaster is a good tool.We know that he has a fuel delivery problem. A MAF isn't going to solve it. You never advised the Scanmaster to check voltage. You advised it to check the MAF. The MAF doesn't effect fuel pressure. you also suggested that he might get an injector and chip package,but we haven't proven that he needs one. We need to look at the things that effect the fuel pressure first,then we can proceed from there. People shouting out guesses from the stands just creates a lot if interrupting noise. We have good cause to suspect the fuel filter. Lets change it to a new AC Delco and see what happens,then go from there looking at voltages and leaks,and vacuum signal interruptions.

 

[ikle]

/

Well the ScanMaster will be able to tell if you have a voltage drop under WOT, low voltage = low pressure. Also I suggested that since the car sat for 5 years and the injectors are original he might want to upgrade them after the fuel pressure issue is solved, so it would be a good idea to uprade the chip at the same time. With the MAF I was giving him an example on how important the ScanMaster is when trying to solve issues on these cars.

Read again, I was giving the op an example of how important a Scanmaster is, again it was just an example !!! I wasn't telling the op that the MAF was bad, I said if it where bad that without a Scanmaster you would be chasing your tail. Also in my first post I suggested he change the fuel filter first, then if the problem is still there check voltage. This is were the Scanmaster would come into play. With it he can see what the voltage is at idle and through the whole rpm band to see if he has any voltage drop. Then from there he would determine if the alternator is going out or if the pump is on its way out. If that doesnt fix his problem he can look into his regulator. My car had a similar problem and it ended up being my new adjustable regulator had multiple leaks, I fixed the leaks problem solved. After the fuel delivery is fixed he might want to upgrade his injectors and chip since the car sat for 5 years. My car sat for a couple years and my new injectors needed to be cleaned and balanced again. So what I learned was when things sit they break. So instead of beating down on people for suggesting something you might want to be a little more professional about it. So let all of us put our heads together and get the op's problem fixed so he can enjoy his car.

 

[ikle]

Also if he had a Scanmaster we could take a look at his BLM's to see if a vacuum leak is present, who nows the vacuum line going to the regulator could be bad. It just makes everything a little easier that's all.

 

[Ttype6]

First I would buy a Scanmaster

This is what you said after he showed us he had a fuel delivery problem.

 

[Ttype6]

Updating your fuel system ( adjustable fuel pressure regulator,fuel pressure gauge,Hotwire kit and fuel pump $300 ) should be your first mod along with a ScanMaster ( $250 ). Make sure you get a fuel pressure gauge ( under $100 )that you can temporally mount under the drivers side wiper arm so you can see if your FP rises 1:1 with the boost . Then since your car sat for 5 years and has the stock injectors you should consider an injector/chip combo upgrade from Eric at Turbo Tweak.

Then you said this. after he told us he has a new pump and Hotwire Kit and confirmed pressure whith a gauge. You said his first mod(no offered diagnostics) should be the Fuel pump and Hotwire along with the Scanmaster.
Then you advised new injectors and a chip.

This is what you said. I can't believe you're disputing this.

The above is a quote from you.

 

[ikle]

The fuel filter was replaced about a year ago, but the car did sit for about 5 years prior to that. I may replace the filter, then hot wire the pump.
The fuel regulator is the stock unit 233.
thnaks

Where did he say he replaced the pump, he said he replaced the filter a year ago and is going to replace it again and hot wire the pump.

 

[ikle]

This is what you said after he showed us he had a fuel delivery problem.

How else would you check voltage under boost, with a volt meter. LOL

 

[ikle]

Then you said this. after he told us he has a new pump and Hotwire Kit and confirmed pressure whith a gauge. You said his first mod(no offered diagnostics) should be the Fuel pump and Hotwire along with the Scanmaster.
Then you advised new injectors and a chip.

This is what you said. I can't believe you're disputing this.



The above is a quote from you.

Purchasing a ScanMaster should be your first mod, then the fuel system should be updated. I don't think the op wants to find out what happens when a 25 year old fuel pump goes out under boost. To many people start modding a TB without getting it to run right first, in order to do this you need to monitor the engines vitals.But right now he wants to fix his fuel delivery issue and I believe this is a step in the right direction.

 

[Ttype6]

I don't think the op wants to find out what happens when a 25 year old fuel pump goes out under boost.

Let me say it again,The OP said in his first post that he has a new pump and Hotwire.

 

[Sinisturbo]

Let me say it again,The OP said in his first post that he has a new pump and Hotwire.

Come on you guys,, I will get to the filter this weekend..