Dose anyone know the stock fuel pressure for a series one l67 from a 1995 buick Rivera.????

My 3800 SC came from a 1995 Buick Riviera. I removed a 4 cyl and recall just putting in the Fiero 6 cyl pump. I don't recall the pressure but would guess that whatever the stock 6 cyl Fiero pressure is correct. (9-12 psi???) I have a fuel system pressure testing kit that I gave to a friend to use this weekend. I should get it back Monday and if you still need the pressure, I'll check mine. (Go figure... That pressure gauge sat under my work bench, collecting dust, for years. I lend it out just two days ago, and now we need it).
Kevin

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85 Fiero-based ASPP GT-40 MarkII. 3800 S/C, Auto, Held suspension all around with 2" drop spindles and sport fr. end. RCC bump-steer correction. Mr. Mike's interior.

3800 Series 1 engines (supercharged and non) ran lower fuel pressures than 3800 Series 2 engines. The service manual says the spec fuel pressure range for a 1995 3800 Series 1 supercharged engine should be 41-47 psi (off boost). With boost, the pressure will be higher.

As with ANY 3800 Supercharged Fiero swap, make sure you are using a fuel pump that is capable of supplying enough pressure and volume of flow for the engine. If you want to use a OE-style (OE-replacement) pump, I suggest using the Delco EP-381. I DO NOT recommend trying to use the "Vette" pump (EP-376) with a supercharged engine.

-ryan

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OVERKILL IS UNDERRATED

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

My car is not making the power it should and seems to misfire with acceleration.
I tested the following

Fuel pressure
Idle 31psi rev 41psi with regulator

idle 41 psi, rev 41psi with regulator vacuum disconnected


Vacuum/ Boost

idle -20 psi / rev +5 boost

New; plugs wires coils belt

[This message has been edited by My fiero forum (edited 04-22-2011).]

quote Originally posted by My fiero forum: My car is not making the power it should and seems to misfire with acceleration. I tested the following Fuel pressure Idle 31psi rev 41psi with regulator idle 41 psi, rev 41psi with regulator vacuum disconnected Vacuum/ Boost idle -20 psi / rev +5 boost New; plugs wires coils belt

Look closely at the fuel pressure regulator and tell me if you can see some small numbers and letters printed in it. We are looking for something that says: "2.7 bar" or "3.0" bar. This is the pressure spec of the regulator (the pressure you should have at the rail with the fuel pump running and no vacuum or boost acting on the regulator).

2.7 bar = 39 psi
3.0 bar = 43.5 psi.

[This message has been edited by Darth Fiero (edited 04-23-2011).]

i Inspected the fpr for Bar with an inspection mirror and could not find anything.

quote Originally posted by Darth Fiero: If you want to use a OE-style (OE-replacement) pump, I suggest using the Delco EP-381. I DO NOT recommend trying to use the "Vette" pump (EP-376) with a supercharged engine. -ryan

Can you explain your reasoning a little further? Does the EP-381 support more HP?

quote Originally posted by nosrac: Can you explain your reasoning a little further? Does the EP-381 support more HP?

The Delco EP-381 was first designed to be used on the GMC Syclone/Typhoon 4.3 Turbo V6 and various later V8 MPFI/SFI applications that required higher fuel pressures and a higher volume flow of fuel at the higher pressures than what the EP-376 pump was designed for. The EP-376 pump was designed for an application that required a maximum fuel pressure of about 47 psi or so that never saw boost. The EP-381 has been tested to supply enough fuel for a 300hp super or turbocharged engine running up to 61 psi of fuel pressure (according to the flow test numbers posted on NAPA Online's website). The EP-376 "Vette" pump will NOT supply this much fuel at this high of a pressure according to several different flow tests I've seen.

Basically, as fuel pressure increases, the volume of fuel flow ANY given electric fuel pump supplies decreases. Better pumps usually start out with higher volume capabilies and don't drop off as quickly as the pressure increases vs. lesser pumps. Trying to use a pump (like the EP-376) in a boosted application that runs higher pressures than what it was designed for could result in starving the engine of fuel which could lead to engine damage.

Bad information has been posted on this forum and elsewhere on the net for years (and continues to be) that says it is safe to run the Vette EP-376 pump in boosted applications; specifically the 3800 Supercharged swap. Well I've posted the data on this forum and my website proving it isn't. Of course, not all pumps are created/built exactly alike, so you MAY get lucky and not have a problem running an EP-376 in a boosted application. I'm recommending to just use the EP-381 instead; it is still a delco OE-replacement pump, but it supplies more volume of fuel flow at higher pressures than the EP-376. Bascially the EP-381 is just a "better" pump. I don't think it is much more expensive than the EP-376, if at all.

Now this 3800 Series 1 SC swap the OP asked about requires less fuel pressure than the 3800 Series 2 and 3 engines. So the use of a pump with higher pressure/volume capabilities is not as critical. But why risk it? Just get the EP-381 pump if you want to run an OE-replacement pump with a 3800 SC engine and call it a day (unless of course you are building a higher-performance engine that is going to require more fuel than even the EP-381 pump can supply).

-ryan