Losing prime
Losing prime Hopefully this is an easy fix. I have a fuel cell with 2 450 pumps, -8 feed to the rails, -6 to the bypass regulator and -6 return to the fuel cell. Key on, everything pressurizes with pumps running. Relays then go off (run by PCM) and the pressure drops to zero. Pumps fo not run while cranking. So my question is, is it dropping through the regulator or siphoning back through the feed? Would adding a check valve be the solution or firing the pumps during cranking? Please help
I have the same setup and same problem. Dual 450s with a aeromotive return regulator and key on it primes then immediately falls to zero. I just live with it. I cycle the key twice then fire it up. But if someone has a simple solution I'm all ears.
I have ordered a -8 check valve and union coupling that will be here tomorrow. I'm going to install it just after the filter as it appears to be siphoning nack through the pumps. I pulled the return line and it stops flowing as soon as the priming cycle stops.
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
Nonsense.
The pumps will always run when the ecu controlling them sees the crank rotating. If they dont, them something is fucked.
How are you determining whether the pumps are running or not ?
The pumps will always run when the ecu controlling them sees the crank rotating. If they dont, them something is fucked.
How are you determining whether the pumps are running or not ?
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Fuel System Check Valve Hi CYR, yes the pumps should run when cranking, ours do with a ten second limit when NO RPM is sensed.
My pumps are equipped with an outlet Check Valve.
This allows for rail pressure exist for 20+ seconds after pumps are off.
This is a measurement that states a good fuel system with no injector leaks into the engine.
YOUR EMS may have that object for pump run time ? (now zero)
Lance
My pumps are equipped with an outlet Check Valve.
This allows for rail pressure exist for 20+ seconds after pumps are off.
This is a measurement that states a good fuel system with no injector leaks into the engine.
YOUR EMS may have that object for pump run time ? (now zero)
Lance
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Verdad Gallardo Hi CYR, yes the pumps should run when cranking, ours do with a ten second limit when NO RPM is sensed.
My pumps are equipped with an outlet Check Valve.
This allows for rail pressure exist for 20+ seconds after pumps are off.
This is a measurement that states a good fuel system with no injector leaks into the engine.
YOUR EMS may have that object for pump run time ? (now zero)
Lance
My pumps are equipped with an outlet Check Valve.
This allows for rail pressure exist for 20+ seconds after pumps are off.
This is a measurement that states a good fuel system with no injector leaks into the engine.
YOUR EMS may have that object for pump run time ? (now zero)
Lance
The pump has never run during cranking with my Gold Box. I have 2 led lights wired to the output on each relay so they light when the pumps run. The Gold Box is not sending a trigger when cranking.
Staging Lane
Joined: Jan 2017
Posts: 67
Likes: 1
do the pump relays have power from the ignition switch in the crank and run position?
Maybe the ECU is commanding the pumps to run but they dont have power when the key is in crank.
I dont remember exactly, but there is a setting is MS to determine what minimum RPM is considered "Cranking" i think 150rpm or close. When MS sees a "Cranking" rpm it will trigger the fuel pumps to run.
Also, I would think after the pumps prime you should be able to maintain fuel pressure for at least a few minutes. Maybe the check valve in the pumps arent working and allowing the fuel to flow backwards, or the rubber line after the pump before that hat is leaking.
Maybe the ECU is commanding the pumps to run but they dont have power when the key is in crank.
I dont remember exactly, but there is a setting is MS to determine what minimum RPM is considered "Cranking" i think 150rpm or close. When MS sees a "Cranking" rpm it will trigger the fuel pumps to run.
Also, I would think after the pumps prime you should be able to maintain fuel pressure for at least a few minutes. Maybe the check valve in the pumps arent working and allowing the fuel to flow backwards, or the rubber line after the pump before that hat is leaking.
stevie: the box isn't faulty as it started fine prior.
Comp: I looked through the settings but frustration is getting the better.
I used a test light and it is triggering a positive signal. Thought it triggered negative. I will be double checking the wiring again in the morning.
Comp: I looked through the settings but frustration is getting the better.
I used a test light and it is triggering a positive signal. Thought it triggered negative. I will be double checking the wiring again in the morning.
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
your last statement is confusing.
The ecu will output a ground to energise the relay to drive the pump.
In the off state, this may appear as close to 12v if tested between the output and ground.
The ecu will output a ground to energise the relay to drive the pump.
In the off state, this may appear as close to 12v if tested between the output and ground.
Okay so I have figured it out. In a rush to get the new fuel system on and back running to go to track I overlooked or forgot that there was a relay already there for the previous setup. MS Box was triggering ground to that relay. So in the rush I had it all wrong. Sorry for this and big thanks for the help.
Fuel pump priming Hi Cyr, I have been manufacturing Electronic Fuel Injection for more than thirty years.
YOUR "tech" is common in that time, an often asked Question.
YOUR help here is GOOD for LS-1 Tech members.
YOUR problem was stated as OK by "MY-2K" and NORMAL.
I believe you have helped MANY, or MANY in the future who will read your Post.
THUS I STATE, "GOOD REPORT"
Lance
YOUR "tech" is common in that time, an often asked Question.
YOUR help here is GOOD for LS-1 Tech members.
YOUR problem was stated as OK by "MY-2K" and NORMAL.
I believe you have helped MANY, or MANY in the future who will read your Post.
THUS I STATE, "GOOD REPORT"
Lance