Fuel pressure dropping SEVERELY under load....
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From: Albuquerque, NM
Fuel pressure dropping SEVERELY under load.... Well this lil problem was kicking my *** with the procharger and continues with my new turbocharged set up.
Fuel pressure is taking a dive under load(BOOST)
I'm talking going from 58 psi down to 20psi and lower sometimes
Not good, especially while trying to nail down a tune and under boost....
Things I suspect
Alternator(battery is always charged, but maybe can't hack it under load??)
Pumps( I have a racetronix set up and an inline pump)
fuel filter
fuel pressure regulator not holding pressure....somehow....
Wire harness to fuel pump
Both pumps turn on and at idle fuel pressure is strong at 58psi and holds steady while cruising, but when I step on it and boost hits...fuel pressure holds for about 2 seconds and dives immediately to 20psi if not lower...i'm immediately out of the throttle then(12psi of boost too, registered a high of 5degs KR so far when this happens
)
I've run this fuel system for a pretty long time now, and its a recent issue so it's been through a ton of miles and WOT passes on the highway and track FWIW.
Any help, recommendations...advice?
Thanks,
J
Fuel pressure is taking a dive under load(BOOST)
I'm talking going from 58 psi down to 20psi and lower sometimes
Not good, especially while trying to nail down a tune and under boost....Things I suspect
Alternator(battery is always charged, but maybe can't hack it under load??)
Pumps( I have a racetronix set up and an inline pump)
fuel filter
fuel pressure regulator not holding pressure....somehow....
Wire harness to fuel pump
Both pumps turn on and at idle fuel pressure is strong at 58psi and holds steady while cruising, but when I step on it and boost hits...fuel pressure holds for about 2 seconds and dives immediately to 20psi if not lower...i'm immediately out of the throttle then(12psi of boost too, registered a high of 5degs KR so far when this happens
)I've run this fuel system for a pretty long time now, and its a recent issue so it's been through a ton of miles and WOT passes on the highway and track FWIW.
Any help, recommendations...advice?
Thanks,
J
Thread Starter
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From: Albuquerque, NM
The intank is about 2 years, the inline about 4 yrs, when tested independently, they both bring FP up to 58 with no problem. I have the inline hooked up to a hobbs switch and its easy to turn the inline on to test it out. The racetronix pump is the only one on at idle and under 5psi.
It could be messed up but hums like new when it powers up and fuel pressure is a strong 58 when jumped on....the pump should be relatively unused since it only turns on at 5psi and rarely passed that on the street, and 1/4mi passed go quickly..
Keep the info coming.
I'm going to buy a filter to start the trouble shooting on the low cost side first
Fuel pressure reg, if it isn't pusing fuel out the reference port, then its still good according to aeromotives tech...but they'd rebuild it for less than 50 if needed.
Alternator....could be it...
J
It could be messed up but hums like new when it powers up and fuel pressure is a strong 58 when jumped on....the pump should be relatively unused since it only turns on at 5psi and rarely passed that on the street, and 1/4mi passed go quickly..
Keep the info coming.
I'm going to buy a filter to start the trouble shooting on the low cost side first
Fuel pressure reg, if it isn't pusing fuel out the reference port, then its still good according to aeromotives tech...but they'd rebuild it for less than 50 if needed.
Alternator....could be it...
J
I was told from MTI and another user that running a inline pump with the racetronix setup is going to restrict it. Thats why for now I am going with the Racetronix and a BAP.
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From: Albuquerque, NM
Heard the same thing too but, I've been running this dual pump set up for about two years with no ill effects and no diving fuel pressure. The inline was running with the stocker 98 pump for even longer with the same results.
So it really hasn't been an issue for me...this is a recent issue that just popped up.
I will be hotwiring the inline pump so it will be running at the same time as the racetronix pump to see if the hobb switch is taking a dump on me, that'll take away one of the things that might be bad...
J
So it really hasn't been an issue for me...this is a recent issue that just popped up.
I will be hotwiring the inline pump so it will be running at the same time as the racetronix pump to see if the hobb switch is taking a dump on me, that'll take away one of the things that might be bad...
J
I take the fuel line in the tank was ok? If the inline is taking a crap time for a dual intank setup. Are your volt's dropping at all at WOT? If they are then it could be the alternater like you said.
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Thread Starter
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From: Albuquerque, NM
Onfire, yep I can do that and thats an awesome idea....damn simple too
Pat, yep I forgot I replaced the rubber stuff with the accordian hose I had left so I was good there, it had small leak but was fixed up with a new clamp.
Voltage seems to stick at 13 volts, but i'll see if I can log that or get a cheapy in car voltage meter(the ones that plug into the cig lighter) for some readings while getting into boost.
Thanks guys, gives me a lot of stuff to check over, should be able to figure it out now
Pat, yep I forgot I replaced the rubber stuff with the accordian hose I had left so I was good there, it had small leak but was fixed up with a new clamp.
Voltage seems to stick at 13 volts, but i'll see if I can log that or get a cheapy in car voltage meter(the ones that plug into the cig lighter) for some readings while getting into boost.
Thanks guys, gives me a lot of stuff to check over, should be able to figure it out now
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1st - I would remove the inline pump. The Incon kits used an intank setup with no inline and Mike Brown's old setup was making 600-700rwhp.
2nd - Is the regulator you are using a "rising rate" type regulator? You should be running a rising rate regulator (1psi per pound of boost) to amintain the fuel demand. If you are not, I would switch.
2nd - Is the regulator you are using a "rising rate" type regulator? You should be running a rising rate regulator (1psi per pound of boost) to amintain the fuel demand. If you are not, I would switch.
Racetronix + voltage blaster, I would not run an inline for the power level you are going for.
One of the pumps is bad, any drop of over 10psi at WOT indicated a problem or worn out part. Maybe the sock came off.
One of the pumps is bad, any drop of over 10psi at WOT indicated a problem or worn out part. Maybe the sock came off.
Just because it can maintain 58 PSI doesnt mean it is delievering the VOLUME of fuel necessary at WOT.
Sounds like a bad pump. Take out the inline and try running to WOT. If you get pressure drop still then it is the intank pump if not remove the inline pump and throw that biznatch in the trisnach
Sounds like a bad pump. Take out the inline and try running to WOT. If you get pressure drop still then it is the intank pump if not remove the inline pump and throw that biznatch in the trisnach
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From: Albuquerque, NM
Well I agree with the consensus, A PUMP IS BAD Now i'm just getting ready to see about putting a twin intank pump set up together.
I emailed Nasty performance to see if he will do me a new fuel pump set up.
Or i'll build a twin set up.
PSJ thanks And the sock is still there and holding strong.
I think the intank pump is bad because the fuel pressure fluctuates at idle and under cruising conditions pretty bad now and getting worse by day. The inline only turns on at 5+psi so this kinda eliminates it from the cruising and idle fuel pressure fluctuations. It'll go from 58 down to 30 back up to 52 drop back down to 20 or so, but if I'm at highway speed with the alternator spinning it'll try its hardest to maintain 58psi.
Removing the inline would be a bitch at this point, thought it would be easier but I looked it over and decided, twin pumps with a -8 or -10 feedline returning back through a -6an line and be done with it.
Now i'm just getting ready to see about putting a twin intank pump set up together. I emailed Nasty performance to see if he will do me a new fuel pump set up.
Or i'll build a twin set up.
PSJ thanks
And the sock is still there and holding strong. I think the intank pump is bad because the fuel pressure fluctuates at idle and under cruising conditions pretty bad now and getting worse by day. The inline only turns on at 5+psi so this kinda eliminates it from the cruising and idle fuel pressure fluctuations. It'll go from 58 down to 30 back up to 52 drop back down to 20 or so, but if I'm at highway speed with the alternator spinning it'll try its hardest to maintain 58psi.
Removing the inline would be a bitch at this point, thought it would be easier but I looked it over and decided, twin pumps with a -8 or -10 feedline returning back through a -6an line and be done with it.
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From: Norn Iron
At anything above about 1200rpm, the alternators output shouldnt really change.
Unless you have accessories on that consume a lot of electrical power when driving, any alternator should easily be able to keep things going and have plenty left to maintain charge in the battery.
I see a lot of posts on this forum talking about alternators and wiring... Do your cars in the US have major wiring problems or something ??
Wiring issues arent something thats ever mentioned or really considered here in the UK and certainly not as far as fuel pumps are concerned..
Alternators are usually only changed or uprated if silly stereos have been fitted.
Unless you have accessories on that consume a lot of electrical power when driving, any alternator should easily be able to keep things going and have plenty left to maintain charge in the battery.
I see a lot of posts on this forum talking about alternators and wiring... Do your cars in the US have major wiring problems or something ??
Wiring issues arent something thats ever mentioned or really considered here in the UK and certainly not as far as fuel pumps are concerned..
Alternators are usually only changed or uprated if silly stereos have been fitted.
does TNT still sell their dual 255 lph walbro pump setup? i'd think that this would be able to keep up with your setup. also, Speed Inc. has some fuel setups you could look at, too.
