Well I now think my problem is with the fuel system. When I turn the key to "on" the fuel pressure does jump to 45-48 psi, however it immediately falls to zero. My dad thought that was normal so he didn't mention it (he was looking at the guage), and the summit tech dept verified that the rail should hold pressure with the key turned to "on". So I believe I've found my problem. Vader, I remember you posted in a thread about using a special crimping tool to block the return line to test the regulator. If it's not the regulator, I'm once again stumped unless it's the pump (eek). The tech guy also mentioned that when the machine shop hot tanked the intake parts they might've used certain acids that could cause porosity in the aluminum. Any thoughts guys? Thanks as always.

------------------
89 Iroc-Z LB9 305 TPI auto 2.73 posi:
3" Dynomax "cat" back,K&N filters, TB bypass, 3" pipe in place of cat, cleaned and flow-matched injectors, 180' thermo, mild ignition mods, synthetic oil, kicker sound system, soon to attempt engine swap...

 

Don't know if this helps, but mine does the same unless the engine is running, then it will keep pressure. With the engine off, key on, you hear the pump, pressure is there, pump stops, pressure drops to zero in about 15 seconds.

By the way, my system is stock, never off the car.

------------------
Rob
'86 TA 305 TPI

 

Well with the plenum off I had one person pinch the return line while another cranked the engine and I watched the guage. The pressure shot to 50psi and then for the first time held at about 38-35 when the key was removed. It bled down and is probably at zero by now. Is this enough evidence for a regulator change? I'm really not sure what else to do...do the plenum and tb have to be on to properly test pressure?

------------------
89 Iroc-Z LB9 305 TPI auto 2.73 posi:
3" Dynomax "cat" back,K&N filters, TB bypass, 3" pipe in place of cat, cleaned and flow-matched injectors, 180' thermo, mild ignition mods, synthetic oil, kicker sound system, soon to attempt engine swap...

 

Also, is it possible for a fpr to malfunction intermittently or does it just crap out?

------------------
89 Iroc-Z LB9 305 TPI auto 2.73 posi:
3" Dynomax "cat" back,K&N filters, TB bypass, 3" pipe in place of cat, cleaned and flow-matched injectors, 180' thermo, mild ignition mods, synthetic oil, kicker sound system, soon to attempt engine swap...

 

You said it drops when the ignition is on. But how does it act when the engine is running?

You will also know when you have a bad regulator because when you disconnect the vacuum hose ...the fuel pressure won't increase.


Tape the gauge on the window (mechanical gauge that is) and take a full throttle run.See if the FP reaches what you set it at (vaccum hose off).



------------------
91 Formula
305 TPI 5speed
1LE/G92/WS6
Custom cold air intake w/K&N, SLP airfoil, ported & polished plenum, TB coolant bypass,Crane AFPR (47psi),94 octane,Crane Extruded Alum. 1.6 full roller rockers, Timing set from 4*BTDC to 10*BTDC,MSD coil,MSD6AL, Holley 9mm Annihilator Laser shot 50 wires, Ac Delco cap,rotor and plugs, Bosch O2sensor, SLP 1 5/8 headers,SLP catback,3:73s,JET 195* fan switch, Macewen white face gauges, Autometer gauges, Zoom hi-performance clutch.
Street legal with stock throttle body, runners,intake manifold,cam, and heads. Coming next..9# Procharger!

 

The car won't stay running at all - it will start and then die immediately. That's why I can't check pressure when the engine is running or drive the car.

------------------
89 Iroc-Z LB9 305 TPI auto 2.73 posi:
3" Dynomax "cat" back,K&N filters, TB bypass, 3" pipe in place of cat, cleaned and flow-matched injectors, 180' thermo, mild ignition mods, synthetic oil, kicker sound system, soon to attempt engine swap...

 

U ROCK,

That sounds like a classic regulator failure to me.

------------------
Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

Thanks - I'm changing the regulator and fuel filter. Would a fpr rebuild kit and the brazing trick be cheaper than an aftermarket kit?

------------------
89 Iroc-Z LB9 305 TPI auto 2.73 posi:
3" Dynomax "cat" back,K&N filters, TB bypass, 3" pipe in place of cat, cleaned and flow-matched injectors, 180' thermo, mild ignition mods, synthetic oil, kicker sound system, soon to attempt engine swap...

 

Yes it would because an aftermarket kit does not include what you need. You need the diaphram and the aftermarket AFPR is only the housing with a threaded insert.

If you pull the vacuum line off while it is running, is there fuel in the vacuum line?

------------------
If you live in Southeastern US, check us out!
South East Thirdgen


ASE Master Tech + L1
Savannah, GA

'87 Trans Am
S/D TPI retrofit including functional PassKey, 22# injectors,
JET AFPR, Ported Plenum,
TB Coolant Bypass, Custom Cold Air,
SSM SFC, KYB Shocks, Boxed LCAs, Wonder Bar,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
-->14.97 @ 94.9 MPH<--

'97 Bonneville SSE

 

I looked in jegs and both the holley and accel ones come with a new diaphragm...

------------------
89 Iroc-Z LB9 305 TPI auto 2.73 posi:
3" Dynomax "cat" back,K&N filters, TB bypass, 3" pipe in place of cat, cleaned and flow-matched injectors, 180' thermo, mild ignition mods, synthetic oil, kicker sound system, soon to attempt engine swap...

 

U ROCK,

An aftermarket kits shows a diaphragm in the photo, but doesn't necessarily include one. The Holley kits never used to include the diaphragm, but they might have changed.

The other problem with the kits is that even a new diaphragm does nothing for the valve seat in the regulator body. If that is damaged, the AFPR kit won't do you much good. There are aftermarket FPRs starting at under $40.00, and you get all the parts new. Convert one of these if you want, and you'll solve your problem and still save some cash.

------------------
Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

That's the route that I think I'm going. An auto place has a stock replacement for $30 that I'm going to modify once I figure out where to buy a brazing rod. There's a minor discrepancy between your two articles - one has the step of banging out the recess in the cap with a 3/4" socket and the other omits this. Which is better?

------------------
89 Iroc-Z LB9 305 TPI auto 2.73 posi:
3" Dynomax "cat" back,K&N filters, TB bypass, 3" pipe in place of cat, cleaned and flow-matched injectors, 180' thermo, mild ignition mods, synthetic oil, kicker sound system, soon to attempt engine swap...

 

Two articles? I thought I only had the current file hangin out there:

AFPR.pdf

If there is another address, it must be the old article on Mike's site. I've modified it since then with a warning about the size of the spacer ball to use, and have recommended dimpling the top of the regulator slightly to allow full adjustment from stock pressure to whatever.

Use the article linked above, since it's most current. I've done three that way and have had excellent results. I had to add the note about the ball so that your pump doesn't get destroyed by dead-heading.

------------------
Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

That's cool I hope you didn't find out the hard way! Yeah the other article is on his page. I'm going to try to get this all done tomorrow - i've been rocless for much too long! Thanks for all your help guys.

------------------
89 Iroc-Z LB9 305 TPI auto 2.73 posi:
3" Dynomax "cat" back,K&N filters, TB bypass, 3" pipe in place of cat, cleaned and flow-matched injectors, 180' thermo, mild ignition mods, synthetic oil, kicker sound system, soon to attempt engine swap...