Why You Need A Fuel Pressure Gauge On The Dash
12-17-12, 03:41 PM
#1
Eye In The Sky
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Why You Need A Fuel Pressure Gauge On The Dash
For the second time in about 13 years, my Denso fuel pump started loosing the ability to maintenance pressure at the higher rpms for boost over 14 psi.
The first time I did not have WI and the Denso was the first upgrade from them for the FD. I noticed knock levels were increasing but safe at the same time fuel pressure was dropping for the higher rpms.
This time with WI, knock was the same but fuel pressure was dropping off again but I was at 17 psi boost. Base FP is 40, Around 6000 rpm the fuel pressure dropped from 57 to 50.
The Aeromotive Stealth pump fixed the problem. No more Denso pumps for me.
While I was at it, I installed gauge 10 new internal wiring for the pump.
Without the fuel pressure gauge, I would not know the pump was wearing out.
Safety First!
The first time I did not have WI and the Denso was the first upgrade from them for the FD. I noticed knock levels were increasing but safe at the same time fuel pressure was dropping for the higher rpms.
This time with WI, knock was the same but fuel pressure was dropping off again but I was at 17 psi boost. Base FP is 40, Around 6000 rpm the fuel pressure dropped from 57 to 50.
The Aeromotive Stealth pump fixed the problem. No more Denso pumps for me.
While I was at it, I installed gauge 10 new internal wiring for the pump.
Without the fuel pressure gauge, I would not know the pump was wearing out.
Safety First!
12-17-12, 05:18 PM
#2
or just a wideband. i do run an electronic fuel pressure gauge also. ive never had a pump go bad, but a FPR crapped out on me. at the time i didnt have a fuel pressure gauge, but could tell something was wrong when it idled in the 10's AFR and leaned out to 13's in boost
12-17-12, 05:26 PM
#3
Wastegate John
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And if you have basically any other ECU other than a PFC you can wire the gauge output into the ECU and have the ecu automatically take protective measures if the fuel pressure drops below your predetermined safe levels.
12-17-12, 08:30 PM
#4
I'm a huge fan of a fuel pressure gage and consider it second to boost as a must-have indicator of engine system health (oil pressure isn't even close). Especially if you retain the unreliable stock fuel pump resistor relay. The most underestimated gage period.
RENESISFD makes an interesting point about using the ECU to elicit alarms/warnings/shutdowns, however for most of us who use a boost dependent FPR, this strategy is infeasible (unless you own a Motec apparently). This argues strongly for running a simplified fixed pressure regulator at ~60psi base fuel pressure, although I've yet to implement it.
RENESISFD makes an interesting point about using the ECU to elicit alarms/warnings/shutdowns, however for most of us who use a boost dependent FPR, this strategy is infeasible (unless you own a Motec apparently). This argues strongly for running a simplified fixed pressure regulator at ~60psi base fuel pressure, although I've yet to implement it.
12-17-12, 10:09 PM
#5
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If you run more than one boost level, then you probably only can have the fuelsafe for the highest boost you run.
My EBC has 4 boost settings. I do have the four top PFC boost rows set for them. I actually tune my total map. I run WI but only the highest boost level is AFR tuned with the water.
The three lower boost settings are AFR tuned without WI.
My EBC has 4 boost settings. I do have the four top PFC boost rows set for them. I actually tune my total map. I run WI but only the highest boost level is AFR tuned with the water.
The three lower boost settings are AFR tuned without WI.
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12-18-12, 07:37 AM
#8
Even the likes of AEM will have these features... AEM already offers it on their infinity ECU's and in an update coming early January, their older AEM Tuner software is getting Fuel/Oil pressure protection, O2 lean protection and improvments to the existing knock control.
12-18-12, 07:59 AM
#9
If you run more than one boost level, then you probably only can have the fuelsafe for the highest boost you run.
My EBC has 4 boost settings. I do have the four top PFC boost rows set for them. I actually tune my total map. I run WI but only the highest boost level is AFR tuned with the water.
The three lower boost settings are AFR tuned without WI.
My EBC has 4 boost settings. I do have the four top PFC boost rows set for them. I actually tune my total map. I run WI but only the highest boost level is AFR tuned with the water.
The three lower boost settings are AFR tuned without WI.
I would hope you tune the entire map...
In addition to the failsafe's mentioned before, most ECU's today have excellent boost control stragities and will allow you to add an input to the ECU that can lower boost if the WI tank low level switch is activated.
And they are not all expensive like Motec, there are many plug and play options that can be had for right around the cost of a new PFC.
12-18-12, 08:32 AM
#10
Wastegate John
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Here is a screen shot of what the engine protection looks like. The reason it is red is because Haltech knows that I do not have a fuel pressure input selected so my settings would be useless here. You can see on the right as C.ludwig mentioned the fuel pressure works off of delta pressure not overall fuel pressure. Obviously that minimum time would need to be changed. IMO, people running single turbo cars should start to open their eyes to other ECU's other than the PFC. Things like this can save an engine. People can sell their PFC and spend another $800-900 on an ECU that is plug and play just like the PFC but have much better control over their engine functions. The PFC is dead for single or non-sequential cars IMO.
Last edited by RENESISFD; 12-18-12 at 08:36 AM.
12-18-12, 10:02 AM
#12
noticed the same issue with the Denso pumps. when they die they don't just quit, they have a tendency to want to take the engine with them on the way out.
doubt i will ever trust a Denso above cosmo TT OE level again, junk.
doubt i will ever trust a Denso above cosmo TT OE level again, junk.
Last edited by RotaryEvolution; 12-18-12 at 10:06 AM.
Back in 1999 I was in fourth grade. But it is now 2012.
12-18-12, 02:11 PM
#15
datalogging can surely point you to the reasons for an engine failure but it won't protect you from it.
wideband gauges are nice, but usually by the time you see the AFRs spiking it's already too late.
thanks, now i feel old. again.
wideband gauges are nice, but usually by the time you see the AFRs spiking it's already too late.
thanks, now i feel old. again.
Last edited by RotaryEvolution; 12-18-12 at 02:13 PM.
12-18-12, 04:11 PM
#17
Racing Rotary Since 1983
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my Denso Cosmo is 13 years old and still running fine. it does get plus 20% additional V in boost thanks to my Kenne Bell Boost A Pump. 40,000 miles of running fine.
i ran 25 psi MGP at 43.5 static this year and it put out 68.5 psi on the dot. maybe your pump was built friday afternoon
this is an important thread.
as Tom indicates, knowing fuel pressure under boost is essential.
watch a gauge
log it
whatever.
but know your pressure in boost.
there are many things that can effect fuel pressure, all negatively, and you don't have to lose all pressure to lose ALL of your engine.
howard
i ran 25 psi MGP at 43.5 static this year and it put out 68.5 psi on the dot. maybe your pump was built friday afternoon
this is an important thread.
as Tom indicates, knowing fuel pressure under boost is essential.
watch a gauge
log it
whatever.
but know your pressure in boost.
there are many things that can effect fuel pressure, all negatively, and you don't have to lose all pressure to lose ALL of your engine.
howard
12-18-12, 06:21 PM
#18
no clue if the Cosmo pumps are still available, if they still manufacture them by chance i probably wouldn't trust one. it would have to be a new old stock pump.
it's easy to say add a guage but in all honesty there are a number of important gauges, and you won't be watching all of them all of the time. best bet is to get a warning threshold type gauge with an alarm. except for many gauges they will fluctuate in and out of warning range normally, so wouldn't really help in that respect with the exception of EGT and ECT. overbuild the engine to hopefully take a pop or 2 to the point that you notice a problem as it arises and can diagnose it.
i hate driving street driven cars that have a thousand gauges and idiot lights, they still wind up eating motors eventually anyways no matter how diligent the owner's are.
Last edited by RotaryEvolution; 12-18-12 at 06:30 PM.
12-18-12, 09:36 PM
#19
Rotary Freak
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I had a supra pump and was loosing fuel pressure. The result was a blown engine. Still not 100% sure if the pump was the issue, relay or how it was rewired - I sold the car.
My new car I swapped the supra pump for an aeromotive 340, and that pump died while I was sitting idling. I had only used it for a few thousand kilometers too. Now I got a new 340 pump.
Any pump can crap out on you. A safety system, and gauges monitoring the FP would be helpful.
My new car I swapped the supra pump for an aeromotive 340, and that pump died while I was sitting idling. I had only used it for a few thousand kilometers too. Now I got a new 340 pump.
Any pump can crap out on you. A safety system, and gauges monitoring the FP would be helpful.
12-18-12, 10:22 PM
#20
Eye In The Sky
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My main two gauges are a boost gauge on the left side and the fuel pressure gauge to the right of it. Easy to glance at both and know what is happening.
12-20-12, 11:51 AM
#24
Great thread. But I need to correct you. Back in 1999 we also had the infamous PFS Purple Peter Motor Eater.
Regards,
Crispy
with *THREE* gauges - boost, FP, and....oil temp (for those of us that are comfortable tracking their car in 100degF ambient temps)
12-20-12, 02:31 PM
#25
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Center speaker location which still allows forward level sight.
Maybe some of us have faster eyes/brains.