Fuel Pressure????
05-03-2005, 12:35 PM
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Fuel Pressure????
On the way back from school I noticed that my fuel pressure was not where it usually goes. When WOT, its always past 100 or alittle over. Now it is about 80-90 LBS. I also inspected the boost and everything seemed fine there. It stays steady at 6 lbs @ WOT. Today the wheather is humid and rainy: (if that will have anything to do with it). Overall the car is working fine and this was just something that I noticed today. It didnt feel like it was taking from the cars performance. I just dont want to ruin the engine. Thanks a lot.
Dan-
Dan-
05-03-2005, 03:17 PM
#3
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How much gas is in your tank? Generally the fuel pressure should remain consistent unless you are really running on empty.
Do you have a AFR meter? That's the best way to tell if something is actually running awry other than a gross drop in fuel pressure. The FPR in the Comptech kit is a rising-rate unit, so one factor could be a small leak in the hose that goes from your manifold to the FPR... if that is bleeding boost away, you won't see the fuel pressure rise as much.
Check all the vacuum-hose connections... especially from the back of the manifold to the FPR (its a red mushroom-like unit that is near the firewall).
Do you have a AFR meter? That's the best way to tell if something is actually running awry other than a gross drop in fuel pressure. The FPR in the Comptech kit is a rising-rate unit, so one factor could be a small leak in the hose that goes from your manifold to the FPR... if that is bleeding boost away, you won't see the fuel pressure rise as much.
Check all the vacuum-hose connections... especially from the back of the manifold to the FPR (its a red mushroom-like unit that is near the firewall).
05-03-2005, 03:22 PM
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yeah, the fuel level is a little low. This might be the cause of it reading the way it does. How ever, I will check the lines that you have mentioned just to be safe.
Thank you allmotor,
Dan
Thank you allmotor,
Dan
05-03-2005, 03:42 PM
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Also check your gauge. I had my fuel pressure gauge sender fail which lead me to think my FPR was busted. I increased pressure based upon my failed gauge which caused problems with drivability (sp?) and fouled my plugs.
Where does pressure sit at idle?
Where does pressure sit at idle?
05-03-2005, 03:59 PM
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Originally Posted by italiaCLs
yeah, the fuel level is a little low.
how low is the fuel?. is the fuel light on?.. you do know if you max boost that car and run out of gas it will go BOOM. ask MrSteve..
05-03-2005, 03:59 PM
#7
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That's a dangerous question because it depends on how the car is tuned. However, I believe for a stock Comptech setup.. its around 34psi w/vacuum. I have mine at 42psi w/vacuum but my rise-rate is much less - hitting about 80psi at 6psi
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05-03-2005, 05:32 PM
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Originally Posted by allmotor_2000
Could be a bad sender, but check the vacuum lines first...
05-03-2005, 07:56 PM
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Originally Posted by italiaCLs
How exactally do I do that? Im not to familiar with workling with fuel lines.
If there is a fuel leak, you'll SMELL it
It is just probably some leakage in the wire from the sendor to the guage... just remove the sendor wire-harness, blow into it.... and plug it back, it should work!
05-03-2005, 10:07 PM
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That sender is a 3 wire unit correct? I gotta find my notes on what the exact voltage at a certain fuel psi should be. I'll get back to you. Basically you'll need to measure the voltage on the grey and purple wires coming off the sender. Let me find my notes and i'll get back to you in the morning.
05-04-2005, 01:38 AM
#21
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What do you guys think about adding a mechanical gauge under the hood in addition to the electronic gauge in the cabin? Summit sells one for $20. Seems like it would be easy to stick inline (Will directly screw into any 1/8 NPT female port)
Overkill?
Overkill?
05-04-2005, 09:24 AM
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Originally Posted by allmotor_2000
^^ Look about 7-8 posts above!
When my gauge failed it was reading 15psi too low. i.e., fuel pressure was actually 39psi at idle, but the gauge read 24psi. At WOT the gauge only hit 85psi, where as it should have said 100psi.
If his fuel pressure gauge reads correctly at idle it might not be a gauge issue.
05-04-2005, 09:31 AM
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Originally Posted by Allout
What do you guys think about adding a mechanical gauge under the hood in addition to the electronic gauge in the cabin? Summit sells one for $20. Seems like it would be easy to stick inline (Will directly screw into any 1/8 NPT female port)
Overkill?
Overkill?
I wouldn't say overkill... but it would be a nice tool to have since it is so easy to install to double check fuel pressure when needed.
05-06-2005, 04:15 PM
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I noticed that the PSI was at 29 LBS at idle. I think that is a little low. I also checked the hoses and didnt smell any gas. There were 3 out let hoses from the FPR. Which is the one that relates to the gauge?
Thanks.
Thanks.
05-06-2005, 04:19 PM
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Originally Posted by italiaCLs
I noticed that the PSI was at 29 LBS at idle. I think that is a little low. I also checked the hoses and didnt smell any gas. There were 3 out let hoses from the FPR. Which is the one that relates to the gauge?
Thanks.
Thanks.
At idle you should be at 37-39 psi... If I am not wrong only one outlet gets plugged in...
05-06-2005, 04:21 PM
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There should be two fittings installed at your OEM pressure regulator. There is a three wire sender going to the fitting. 29psi is too low for idle. Should be about 39psi. Call autometer and ask them what the voltage should read at 29psi; i couldnt' find my notes.
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