Discussion
Hi y'all - I've installed an 'e-rod' LS3 (6.2) into my Rolls Royce and all seems fine except that when driven the engine hiccups and lurches when I put my foot down. I'm assuming its something to do with the fuel as it rev's fine in the garage; it just misbehaves when under load.
It has the right chevy pressure regulator in the fuel line. I'm digging out the info on the fuel pump (it should be 40 gph/ 60 PSI). One thing that may be a problem is that I'm running it from the old Rolls fuel tank. I've taken the return from the pressure regulator and put a fitting in the fill-up plumbing so the return has somewhere to go. Is there something else I need to do to the tank maybe? Bigger vents to prevent a vaccum?
Anyway, any thoughts appreciated.
It has the right chevy pressure regulator in the fuel line. I'm digging out the info on the fuel pump (it should be 40 gph/ 60 PSI). One thing that may be a problem is that I'm running it from the old Rolls fuel tank. I've taken the return from the pressure regulator and put a fitting in the fill-up plumbing so the return has somewhere to go. Is there something else I need to do to the tank maybe? Bigger vents to prevent a vaccum?
Anyway, any thoughts appreciated.
fatbutt said:
Hi y'all - I've installed an 'e-rod' LS3 (6.2) into my Rolls Royce and all seems fine except that when driven the engine hiccups and lurches when I put my foot down. I'm assuming its something to do with the fuel as it rev's fine in the garage; it just misbehaves when under load.
It has the right chevy pressure regulator in the fuel line. I'm digging out the info on the fuel pump (it should be 40 gph/ 60 PSI). One thing that may be a problem is that I'm running it from the old Rolls fuel tank. I've taken the return from the pressure regulator and put a fitting in the fill-up plumbing so the return has somewhere to go. Is there something else I need to do to the tank maybe? Bigger vents to prevent a vaccum?
Anyway, any thoughts appreciated.
Has it ever ran correctly ? What ecu ? Are you getting any fault codes ?It has the right chevy pressure regulator in the fuel line. I'm digging out the info on the fuel pump (it should be 40 gph/ 60 PSI). One thing that may be a problem is that I'm running it from the old Rolls fuel tank. I've taken the return from the pressure regulator and put a fitting in the fill-up plumbing so the return has somewhere to go. Is there something else I need to do to the tank maybe? Bigger vents to prevent a vaccum?
Anyway, any thoughts appreciated.
And if you are in doubt about the fuel system, draw a schematic of exactly what you are working with currently.
Sardonicus said:
Are you using an EFI fuel tank if not you will get major fuel surge every time you hit the throttle due to surge i.e.fuel rushing away from the fuel tank outlet to your fuel pump.
Yeah, that's something that seems to fox the 'experts' over here. The tank isn't EFI and when I ask the hot rodders here they say that as long as I have the return going back there then its not an issue. Is there a mod I can do to the tank such as another vent or something to prevent this? Or does an EFI tank differ in that it has baffles in there or something?Note: the fuel pump is external to the tank.
stevieturbo said:
Has it ever ran correctly ? What ecu ? Are you getting any fault codes ?
And if you are in doubt about the fuel system, draw a schematic of exactly what you are working with currently.
Its a work in progress and like I say it runs fine the garage. Its when its under load that it gets lumpy. Feels like fuel starvation or throttling but all I have is a tank output, pipework to the fuel pump, pipework from the pump to a combined relief/ filter then pipework to the fuel rail.And if you are in doubt about the fuel system, draw a schematic of exactly what you are working with currently.
The ECU is the one that comes with the E-rod package so its all pre-set. I have a fault code reader but not tried that yet - I'll give it a got later.
An EFI tank will always have some sort of internal collector setup. The return also usually returns to this area
EFI pumps must never see air, and they must always have a good unrestricted gravity feed of fuel
Hence if you think fuel issues are the problem draw a schematic of exactly what you have so we can try and diagnose.
ie, entire layout including pipe sizes, filters, type of filter etc.
But even the term under load is vague. Under load and under load in a scenario that might cause fuel surge arent the same thing.
And if the tank is even half decent and full of fuel, fuel surge should not be an issue. Even a badly designed tank should still work as long as it's full...unless the fuel outlets ere very bad also.
EFI pumps must never see air, and they must always have a good unrestricted gravity feed of fuel
Hence if you think fuel issues are the problem draw a schematic of exactly what you have so we can try and diagnose.
ie, entire layout including pipe sizes, filters, type of filter etc.
But even the term under load is vague. Under load and under load in a scenario that might cause fuel surge arent the same thing.
And if the tank is even half decent and full of fuel, fuel surge should not be an issue. Even a badly designed tank should still work as long as it's full...unless the fuel outlets ere very bad also.
As has been hinted at but not stated directly fill the tank to the brim and try again. With the tank full surge cannot be the issue.
A further question....where is the efi pump mounted? To work well it should be level with or below the bottom of the tank as efi pumps do not like having the suck.
Steve
A further question....where is the efi pump mounted? To work well it should be level with or below the bottom of the tank as efi pumps do not like having the suck.
Steve
Steve_D said:
As has been hinted at but not stated directly fill the tank to the brim and try again. With the tank full surge cannot be the issue.
A further question....where is the efi pump mounted? To work well it should be level with or below the bottom of the tank as efi pumps do not like having the suck.
Steve
The tank is full as of last week so was full when I drove it and experienced the lumpy/ surging. The pump is below the tanks level, mounted on the chassis near the rear wheels.A further question....where is the efi pump mounted? To work well it should be level with or below the bottom of the tank as efi pumps do not like having the suck.
Steve
you will likely get pump cavitation if the fuel pump is not mounted in the tank or within very short distance.
mount a fuel pressure gauge and check if the fuel pressure remains constant or within the expected range if plenum pressure referenced.
I'd expect it to drop as flow demand rises. -> cavitation.
This is all assuming you run a properly mapped ECU, e.g. a OEM ECU for that engine.
mount a fuel pressure gauge and check if the fuel pressure remains constant or within the expected range if plenum pressure referenced.
I'd expect it to drop as flow demand rises. -> cavitation.
This is all assuming you run a properly mapped ECU, e.g. a OEM ECU for that engine.
Ive said:
you will likely get pump cavitation if the fuel pump is not mounted in the tank or within very short distance.
mount a fuel pressure gauge and check if the fuel pressure remains constant or within the expected range if plenum pressure referenced.
I'd expect it to drop as flow demand rises. -> cavitation.
This is all assuming you run a properly mapped ECU, e.g. a OEM ECU for that engine.
Good point. I ordered a fuel pressure gauge last night so I should have that next week. mount a fuel pressure gauge and check if the fuel pressure remains constant or within the expected range if plenum pressure referenced.
I'd expect it to drop as flow demand rises. -> cavitation.
This is all assuming you run a properly mapped ECU, e.g. a OEM ECU for that engine.
The pump is about 6 inches from the output of the tank so I hope that's close enough. Might struggle to get it closer.
The ECU comes from Chevy as part of the package so the mapping should be good.
A rather basic test that strikes one as the first thing to do is check the output of the fuel pump. Disconnect the fuel line from the injector rail, hook the pump directly to a battery and measure the flow. Approx 30 litres/hour per 100 bhp is the approximate consumption of a stock engine at WOT and with a decent safety margin for pump wear ideally 40/45 litres/hour per 100 bhp.
Google seems to think your engine has about 430 bhp as stock so you're looking at about 3 litres per minute (180 l/hr) to be safe. This of course will be flow without any pressure regulator in the circuit and at 3 bar fuel pressure the flow might well be less. However it puts you in the ballpark.
Your 40 gph (180 l/hr) pump would seem only just big enough even if it is working perfectly.
Google seems to think your engine has about 430 bhp as stock so you're looking at about 3 litres per minute (180 l/hr) to be safe. This of course will be flow without any pressure regulator in the circuit and at 3 bar fuel pressure the flow might well be less. However it puts you in the ballpark.
Your 40 gph (180 l/hr) pump would seem only just big enough even if it is working perfectly.
Turns out that I still had a secondary fuel filter in the line from when I had a separate relief and filter. It was buried in the paneling I'd put back up...
Now removed. No restriction
But, managed to ding the exhaust when pulling out of the garage (its low!) so now have a blowing exhaust otherwise I'd have a youtube video up
Now removed. No restriction
But, managed to ding the exhaust when pulling out of the garage (its low!) so now have a blowing exhaust otherwise I'd have a youtube video up
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