TT5.9mag
Two atmospheres are better than one
I remember those. I used a 12:1 FMU to run boost on a 5.0 Ford with stock injectors before we could tune em, or had the availability of injectors and pumps we have now.
71 Duster 360 turbo build
- Thread starter turbovan
- Start date
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I've ran into issues running multiple pumps with my GLH. One pump could not keep up with the other resulting in the engine starving for fuel. Just my opinion but I would try one big pump
Surge tank is in, but having “fun” getting the 20ish new cheap AN fittings to stop leaking. Disaster so far. In tank pump is wired up and seems to work well.
Trans is all back together with the addition of a billet input shaft, lightened sun shell, and billet rear clutch drum.
Trans is all back together with the addition of a billet input shaft, lightened sun shell, and billet rear clutch drum.
I assume you saw a drop in pressure which led you back to pumps as the issue? My pressures have been holding pretty steady, and I’ll be utilizing the same two pumps as before; just a different orientation. The surge tank is just to prevent starvation as my sump wasn’t cutting it(installed wrong with entire opening cut out).
No. This was in my GLH. I didn't have a fuel pressure gage. The car would haul *** in 1st and 2nd but misfire in third when the demand for fuel was greater. Chased this problem for a few years... I finally told my problem to a new tuner and he asked this question about my fuel pump set up... When I told him that I had 2 pumps in sequence in there, a small one (in tank), feeding the bigger one (on frame rail), he told me that was a "no-no"... I removed the smaller in tank pump and just used the frame rail pump (which was big enough for my setup). My issue disappeared. Lesson learned
TT5.9mag
Two atmospheres are better than one
Your tuner was smart.
Two pumps in series will always only flow what the smaller pump is capable of flowing.
Exactly what he told me... The engine was starving for fuel.
Fuel system finished, and about to install the transmission. I struggled to get the new PTC converter seated correctly, but it finally slid all the way in. I noticed that the converter drive hub on this converter is only 2” where as my old converter is 2.5”. Is this something I need to worry about? I don’t want poor pump tang engagement…
Old converter pic for reference
Old converter pic for reference
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To be clear, a surge tank utilizes an unrestricted in tank pump as a feeder. So it should be able to keep up with the two 400lph pumps located within the surge tank running at pressure. The tank also holds 3.8L of fuel. Altogether I don’t believe I’ll be able to drain it in ~10 seconds.
Transmission is in. Took it for a drive and everything seems to be working fine. Stalled the new converter up to 3500, and it may go a bit higher, but the engine is bogging hard. With no changes to the tune it’s running pig rich under boost; under 10:1. Double checked the fuel pressure, and verified it’s rising slightly less than 1:1. Normal driving AFR’s are still exactly where I left them. I’m hopeful that the new fuel system really is that much better so I can up the boost a bit more! Tomorrow is probably the last cool track night of the year so I’m thinking about going if I can get the tune dialed in time.
I’m having a little trouble with my fuel pressure sensor if anyone has a suggestion.
The sensor reads correctly with the engine off(60-80psi), but reads roughly 15% high while driving. The sensor is using the megasquirt sensor ground.
The sensor reads correctly with the engine off(60-80psi), but reads roughly 15% high while driving. The sensor is using the megasquirt sensor ground.
What kind of sensor? Like a generic 0-100psi connected to Generic Inputs? Where is it installed, at the FPR?
Generic 0-100 installed on the pressure line right before fuel pressure regulator
Boost referenced FPR? If it is you’d usually see a small drop in fuel pressure when the FPR sees vacuum, not an increase. Not sure if sensor placement would have any impact. My sensor is installed in the FPR body.
Also what does the generic sensor calibration look like in TunerStudio? Is it a 0-5v sensor?
Yes. Gauge on the FPR set to 60 static, pulls to 50ish at idle, and 1:1 rise with boost.
0-5 sensor. Again, it reads correctly in the garage with the pump running and motor off.
A real head scratcher. Seems you have your bases covered. What’s different between motor off and motor running from the ECU’s standpoint? Do you maybe turn on the 2nd pump only when above a certain RPM?
I was out tuning my VE table today, and the numbers were too far off to continue so I went through all the other tables to look for problems. And I found it. The fuel injector size was set to 851cc; on every tune in my laptop. Even tried restore points from November; 851cc. This isn’t the first time something like this has happened with Tuner Studio, but definitely the most significant.
Anyways, running great now on the same time I used at the track. Out of time to hit the strip tonight, and the next test n tune isn’t until 4/25.
Anyways, running great now on the same time I used at the track. Out of time to hit the strip tonight, and the next test n tune isn’t until 4/25.
Turbosmblk
Well-Known Member
Remote mount the sensor on the firewall as a test. Being mounted on the engine has been known to cause problems killing sensors and making them read erratic from vibration. At least on Holley and haltech etc anyway.
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