what happens when you prime your fuel system?
10-10-05, 04:37 PM
#1
what happens when you prime your fuel system?
whenever i prime my fuel pump (running haltech, so the walbro kicks on when the key is at ON for a couple seconds) the pressure shoots up to 50 or so, then as soon as the pump shuts off, the pressure instantly drops down to 5psi or so then slowly down to zero...
does this mean i have a bad check valve or is the pressure supposed to release when the pump shuts off? this also leads to another question..
if this check valve is bad, would that not let me aeromotive FPR raise the pressure under boost? maybe the extra pressure is just going back into the tank... any input on this would be appreciated.
does this mean i have a bad check valve or is the pressure supposed to release when the pump shuts off? this also leads to another question..
if this check valve is bad, would that not let me aeromotive FPR raise the pressure under boost? maybe the extra pressure is just going back into the tank... any input on this would be appreciated.
10-10-05, 04:44 PM
#2
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Im pretty sure the pressure is just supposed to bleed off back in the return lines, because i know it primes with the turn of the key. Do you want to run more than 50psi of fuel pressure?
10-10-05, 06:04 PM
#4
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It should only bleed down the where the FPR is set. If it spikes to 50 psi, and you have the FPR set to 45, it should bleed down to 45 and stay there (maybe bleed off a little more over time, but not quickly).
-Marques
-Marques
10-10-05, 08:51 PM
#5
interesting... i turn my key, the haltech turns the walbro on, it shoots to 50 or so, then bleeds all the way down... could it have anything to do with my fpr being on the return side?
does anyone have any input to what this would do under boost? it seems to me like
does anyone have any input to what this would do under boost? it seems to me like
10-10-05, 10:50 PM
#6
Originally Posted by mwatson184
It should only bleed down the where the FPR is set. If it spikes to 50 psi, and you have the FPR set to 45, it should bleed down to 45 and stay there (maybe bleed off a little more over time, but not quickly).
-Marques
-Marques
so what would make it bleed off? and would this have any affect on the pressure rising 1:1 under boost?
10-11-05, 02:29 AM
#7
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Originally Posted by jacobcartmill
whenever i prime my fuel pump (running haltech, so the walbro kicks on when the key is at ON for a couple seconds) the pressure shoots up to 50 or so, then as soon as the pump shuts off, the pressure instantly drops down to 5psi or so then slowly down to zero...
does this mean i have a bad check valve or is the pressure supposed to release when the pump shuts off? this also leads to another question..
if this check valve is bad, would that not let me aeromotive FPR raise the pressure under boost? maybe the extra pressure is just going back into the tank... any input on this would be appreciated.
does this mean i have a bad check valve or is the pressure supposed to release when the pump shuts off? this also leads to another question..
if this check valve is bad, would that not let me aeromotive FPR raise the pressure under boost? maybe the extra pressure is just going back into the tank... any input on this would be appreciated.
Sounds normal to me, the pump needs to be running to maintain pressure. Just checked on my car and I get pretty much identical behavior as you see (I'm using Electromotive and an SX pump).
If you are concerned about fuel pressure, you should watch it while you are running the engine. With a rising rate regulator you should see the pressure go up under boost (you should be able to see this even blipping the throttle at no load).
-Andy
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10-11-05, 12:32 PM
#8
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Originally Posted by jacobcartmill
so what would make it bleed off? and would this have any affect on the pressure rising 1:1 under boost?
10-11-05, 02:25 PM
#10
My E6k, Walbro and Aeromotive PR did the same thing except the bleed down in pressure was slower ~1/2hr to bleed down.
When you put in the -6an flare fittings into the Aeromotive PR make sure they are the o-ring seal kind without the flare on the end you are sticking into the PR or the end of the flare will be RIGHT next to the FPR internals and it will cause pressure spikes from limited fuel return capacity.
If you do use regular double flare -6an fittings make sure you cut the flares off the FPR end and just leave the threads.
I made that mistake whe I first put in my fuel system and it made a weird squeeky/squealy noise during priming when the return fuel was first squirted past the close fit and it caused pressure regulation issues.
When you put in the -6an flare fittings into the Aeromotive PR make sure they are the o-ring seal kind without the flare on the end you are sticking into the PR or the end of the flare will be RIGHT next to the FPR internals and it will cause pressure spikes from limited fuel return capacity.
If you do use regular double flare -6an fittings make sure you cut the flares off the FPR end and just leave the threads.
I made that mistake whe I first put in my fuel system and it made a weird squeeky/squealy noise during priming when the return fuel was first squirted past the close fit and it caused pressure regulation issues.
10-13-05, 12:34 AM
#11
what do you mean by double flare fittings?
this is what i used for the plug:
(with an oring of course) 
as for the straight male/male adapters for the in/drain on the FPR, i believe i used the "regular" style that you speak of, but if you could provide a picture that would be super.
also, could you elaborate on this a little more? i've never heard of this.
this is what i used for the plug:
(with an oring of course) as for the straight male/male adapters for the in/drain on the FPR, i believe i used the "regular" style that you speak of, but if you could provide a picture that would be super.
also, could you elaborate on this a little more? i've never heard of this.
Last edited by jacobcartmill; 10-13-05 at 12:41 AM.
10-13-05, 02:54 PM
#12
If you used a double flare end in the fuel pressure regulator like this you are restricting return flow to the tank and will likely have fuel spike issues.
You must use an o-ring seal an to flare an fitting like this (or cut the flare off the part of the double flare fitting to make it look like this) so that the non flared end goes into the regulator.
You must use an o-ring seal an to flare an fitting like this (or cut the flare off the part of the double flare fitting to make it look like this) so that the non flared end goes into the regulator.
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