Fuel Pump EMI Noise Suppression

[Spittybug]

There you go Shannon, a ~$6.00 (pair) potential solution to try.

[lazabby]

There you go Shannon, a ~$6.00 (pair) potential solution to try.

There's a RS by my house so I'll go by and pick up a couple of them. I hope it works. If life could only be so easy.

[DniveK]

Seems to be an error in the PDF file, I was unable to open it. How about a High-Pass filter on the line? Usually used to stop noise from motors.

[lazabby]

I went by Radio Shack and picked up the piece that Owen found online. I clamped one on the electrical wires going to the fuel pump. I clamped the other to the wires going to the fuel sending unit. I did not loop the wires one time as suggested by Dave. I might have been able to loop it if I used one piece for each wire going to the fuel pump. I started the car and still had sync loss issues when I tried revving the car up to close to 3,000 RPM (automatic).

Just to let you know, a few weeks back I disconnected the alternator and took the belt off and started the car. Still had sync loss issues. Several days ago I removed every fuse that wasn't necessary for the car to run. Still had sync loss issues.

We're operating under the assumption that there is EMI causing the sync loss issue at high RPMs. If this is the case, then we're down to fuel pump, spark plug wires and distributor, unless I'm missing something else. The sync loss is occurring on two automobiles using the Megasquirt 3.57. One car is automatic (mine) and one is a manual.

Any more ideas of what to try?

[Bitsyncmaster]

You don't need one on the fuel sender. Put one on each wire to the fuel pump and see if that helps. I can send you some larger units you will have to wrap the wire in but I'm thinking you're pump is not the cause of the problem.

I'm thinking the filter used in the ECU for reading RPM off the coil is not optimal. I could give you one of my idle ECU boards with my filter circuit to try. I use an optical isolator and some RC filters. It would need +12 volt power and ground.

[lazabby]

You don't need one on the fuel sender. Put one on each wire to the fuel pump and see if that helps. I can send you some larger units you will have to wrap the wire in but I'm thinking you're pump is not the cause of the problem.

I'm thinking the filter used in the ECU for reading RPM off the coil is not optimal. I could give you one of my idle ECU boards with my filter circuit to try. I use an optical isolator and some RC filters. It would need +12 volt power and ground.

Tomorrow I'll re-do the setup and use one clamp core on each wire going to the fuel pump. I should be able to wrap the wires one time. I have to take off the rubber boot on top of the fuel pump in order to get at enough wire length. I'll try that and see what happens. If it still doesn't work, I may try clamping one on at the Megasquirt unit. I'll take you up on the offer on the ECU board if everything fails.

[Spittybug]

You don't need one on the fuel sender. Put one on each wire to the fuel pump and see if that helps. I can send you some larger units you will have to wrap the wire in but I'm thinking you're pump is not the cause of the problem.

I'm thinking the filter used in the ECU for reading RPM off the coil is not optimal. I could give you one of my idle ECU boards with my filter circuit to try. I use an optical isolator and some RC filters. It would need +12 volt power and ground.

Dave, I'm not sure I'm reading you properly..... we are triggering directly from the VR coil in the dizzy, not the ignition coil (tach signal). How would your board interface with this setup? What am I missing?

[DniveK]

Could be the wire from the coil to the distributor is not shielded properly, I think that would cause the most EMI.

[Spittybug]

Fully foil shielded, grounded on one end only, run independently of all other wires, away from spark wires, etc... been there tried that!

[Bitsyncmaster]

Dave, I'm not sure I'm reading you properly..... we are triggering directly from the VR coil in the dizzy, not the ignition coil (tach signal). How would your board interface with this setup? What am I missing?

If your running the VR coil for RPM than that should be better than using the ignition coil. Is that VR coil wire shielded?