Help. Won't start. Fuel pressure drops after key on? Regulator or pump?
08-13-2016, 03:47 PM
#1
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Help. Won't start. Fuel pressure drops after key on? Regulator or pump? Looking for ideas on where the problem is.
95 5.7 firebird.
I am running an aero motive boost referenced fuel pressure regulator. 255 Walbro pump.
Car died while I was driving down the road.
Car won't fire now.
Checked for spark.....I am good. Spark at coil and plugs. (Can I assume this means opti is ok?)
Checked fuel. I get pressure at key on and while cranking, but if I go key on without cranking, pressure spikes then drops very quickly.
Do I have a fuel pump or fuel pressure regulator problem?
Here is a video of key on pressure drop.
95 5.7 firebird.
I am running an aero motive boost referenced fuel pressure regulator. 255 Walbro pump.
Car died while I was driving down the road.
Car won't fire now.
Checked for spark.....I am good. Spark at coil and plugs. (Can I assume this means opti is ok?)
Checked fuel. I get pressure at key on and while cranking, but if I go key on without cranking, pressure spikes then drops very quickly.
Do I have a fuel pump or fuel pressure regulator problem?
Here is a video of key on pressure drop.
Last edited by real82it; 08-13-2016 at 10:52 PM.
08-13-2016, 04:58 PM
#2
does the FP hold while driving, especially on WOT run?
You say it just doesn't run so I would suspect no
My personal experience with Aeromotive FPR was not good
Since initial FP spikes during the few seconds pump primes KOEO....I would look into the FPR. Maybe swap back to the stock one for test to see
You say it just doesn't run so I would suspect no
My personal experience with Aeromotive FPR was not good
Since initial FP spikes during the few seconds pump primes KOEO....I would look into the FPR. Maybe swap back to the stock one for test to see
08-13-2016, 05:49 PM
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does the FP hold while driving, especially on WOT run?
You say it just doesn't run so I would suspect no
My personal experience with Aeromotive FPR was not good
Since initial FP spikes during the few seconds pump primes KOEO....I would look into the FPR. Maybe swap back to the stock one for test to see
You say it just doesn't run so I would suspect no
My personal experience with Aeromotive FPR was not good
Since initial FP spikes during the few seconds pump primes KOEO....I would look into the FPR. Maybe swap back to the stock one for test to see
I don't have my stock regulator anymore to swap and test.
I am trying to get it running again. Confirmed I have spark. Now trying to see if I have fuel. I have pressure at key on and when cranking, but the quick drop has me concerned.
08-13-2016, 07:44 PM
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this the FPR you have?
https://www.summitracing.com/parts/a...FcZahgodQAwP8Q
pull the vacuum nipple off...is there any sign of fuel?
if yes the FPR is bad
https://www.summitracing.com/parts/a...FcZahgodQAwP8Q
pull the vacuum nipple off...is there any sign of fuel?
if yes the FPR is bad
08-13-2016, 07:49 PM
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I updated the video above to show cranking pressure also.
If you listen closely, you can hear a slight "whoop, whoop" as it cranks. Very strange sound. It is not quite a backfire.....more like what a car sounds like when the timing is way off. The last time I remember hearing a car sound like this is when I accidentally installed a cam 8 degrees advanced or when I dropped a distributor in 180 off and cranked. I have no idea how timing could be off or change on this car.
I would love any other ideas about what broke or what to check next. I was just cruising down the road about 30 mph, the car sputtered and died.
I have no codes/SES light.
I guess I will put a NOID light on the fuel injector plugs tomorrow and make sure they are getting a signal to fire.
If you listen closely, you can hear a slight "whoop, whoop" as it cranks. Very strange sound. It is not quite a backfire.....more like what a car sounds like when the timing is way off. The last time I remember hearing a car sound like this is when I accidentally installed a cam 8 degrees advanced or when I dropped a distributor in 180 off and cranked. I have no idea how timing could be off or change on this car.
I would love any other ideas about what broke or what to check next. I was just cruising down the road about 30 mph, the car sputtered and died.
I have no codes/SES light.
I guess I will put a NOID light on the fuel injector plugs tomorrow and make sure they are getting a signal to fire.
Last edited by real82it; 08-13-2016 at 10:53 PM.
08-14-2016, 07:41 PM
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Anyone else have any ideas on what I could check next?
To summarize:
Car won't start
I have spark at coil and plugs
I have fuel pressure at key on and crank
No DTC codes
Not sure where to look next.
To summarize:
Car won't start
I have spark at coil and plugs
I have fuel pressure at key on and crank
No DTC codes
Not sure where to look next.
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08-15-2016, 09:46 AM
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09-23-2016, 06:02 PM
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And the problem was........the rotor screws on the MSD opti fell out! Rotor was free floating on the cap. Amazed I still got spark with it that way! Well, screws are tight with loc-tite now!
09-24-2016, 01:05 AM
#13
Glad you got your issue figured out. I just replaced the cap and rotor on the MSD opti in my buddies road race car, single best thing we could have done for it. We usually disassemble it quarterly to clean the terminals to try and get rid of the pesky misfire, new cap and rotor did it for now. Oh well, 24x in the future.