Fuel Pressure Control.

[Trump]

My V3 board has a faulty fuel pump output circuit and to overcome this I use the Inj G output to drive the fuel pump relay once it detects a RPM of 10.

This is working OK but I would like to be able to utilize the priming pulse feature of the standard fuel pump drive. Is it possible to use the Fuel Pump Pressure control to get the priming option and still use the Inj G output to drive the pump?

[elutionsdesign]

3.4.7.1 Priming pulse
This curve allows you to specify an initial pulse, in milliseconds, that is fired on the first turn of the key. You
can set the pulse width as a function of coolant temperature.

Are you referring to a prime pulse, or an initial run of the fuel pump when the key first turns ON to pressurize the system? The priming pulse is fired by the injectors.

[jsmcortina]

Surely the best is to fix the fault on the board?

James

[nathaninwa]

I agree with James on fixing the board, but the short awnser is yes, you can program the output to run the pump for less than the seconds desired. I run a staged pump and have key cycle along with coming on with a tps value

[Trump]

Fix the board sounds the obvious answer and I have been down that track. sent it off to the USA for repair and converting to MS2 Extra. Came back with with MS2 Extra upgrade but not the fix. Tried myself but failed. The alternative has worked well until my upgrade to ITB. Still working OK but would like to utilise the Priming pulse (inj fires) on start.

If the fuel pump pressure control is used, does it go through the same steps ie fuel pump on for 2 seconds and a programmed priming pulse?

[Trump]

The reason I am chasing the priming pulse is a start issue. On first start of the day it will fire OK and get up to idle but then die. All other starts show a lean mixture for the first second or so before settling down. The logs show that it is in fact lean. The AFR and pulse width do not seem to match.

This issue surfaced when I converted to individual throttle bodies and IBT tune.

I have increased the ASE and Cranking pulse but no diff. My thought was that a good priming pulse would help.

It is warm here now and I am concerned that when winter comes I will have some real start issues.

[Dasman56]

I'm using one of the PWM outputs for fuel pump control. You should be able to set it up as Open-loop PWM and set all your targets to 100 % duty.
I have it set up like this and it primes on start up and key on the same as the regular fuel pump output.

[Trump]

Thanks. Just tried that and now fuel pump runs OK on key on but continues to run. Regular set up only runs for 2 seconds unless engine is turning. I can live with this if I get my prime. Will try it on start tomorrow.

Do not know if it primes.need to check that. Does your pump continue running even if the engine is not turning?

[Dasman56]

No it does not continue to run. It primes for two seconds at start up only. Then runs again during cranking

[nathaninwa]

Just use the and/or option under the programming. Leave the one at 10rpm, then use the or and set it up for less than 2 seconds

[Dasman56]

Just to make sure there is no confusion on how I set mine up. I'm using one of the spare PWM outputs but set up in the "FUEL PUMP and PRESSURE CONTROL" settings. Not the Generic PWM output menu.

[Trump]

Set up the Fuel Pressure control as suggested. the pump starts and runs for 2 secs and stops. Engine will not start as pump does not run except for the 2 secs on key on.

I can not set the pump to run with the Programmable ON/Off Outputs as the output (Inj G) is already allocated to the Fuel Pump Pressure Control.

I may need to connect both Inj G plus another output to the fuel pump relay so that either can control the pump.

[jsmcortina]

Set up the Fuel Pressure control as suggested. the pump starts and runs for 2 secs and stops. Engine will not start as pump does not run except for the 2 secs on key on.

Post your MSQ.

James

[Trump]

My msq is on this thread but here it is again.

[Dasman56]

Trump, I think James was asking you to post up your current "new" MSQ showing how you now have the Fuel pressure control setup.

[Trump]

Sorry James. This is the tune I used to try the Fuel Pump Pressure Control option.
The pump started on key on, run for 2 seconds then stopped. The engine would not start and I could not hear the pump running. Inj G is the output used.

[grom_e30]

set all your targets to 100 % duty.

[Trump]

With all duty cycles set to 100% the fuel pump starts on key on and stays on but stops when the engine cranks. With Idles cycle set to 0% the fuel pump starts on key on and stops after 2 seconds but will not restart on crank.

[nathaninwa]

look at programmable outputs, high current out 2. where I use tps you use your greater than 10rpm

[Trump]

Ah yes. I see where you are coming from but if the MS fuel pump control has failed what turns the pump on?

If my interpretation is correct, the pump turns on when the TPS is greater than 15% and in less than 2 seconds??