Coil drive relocation and heatsink design.

[Devastator]

I had this same problem...turned out to be a flat cam lobe i hope yours is the driver.

Yikes!
I've already verified that it's either the coil or the driver(s). I lose spark on #1 and #3 cylinders after things warm up.

[Devastator]

I made progress I think.
Both of my coil drivers are now of the newer style BIP 373's. I need to adjust the dwell still, but the engine fired up and ran. That's a start. My buddy Steve noted that the problem likely existed with having the fuel pumps and coil hooked to the same relay. Changed that too.

[Dale M.]

I made progress I think.
Both of my coil drivers are now of the newer style. I need to adjust the dwell still, but the engine fired up and ran. That's a start. My buddy Steve noted that the problem likely existed with having the fuel pumps and coil hooked to the same relay. Changed that too.

Both circuits hooked to single relay should NOT have any effect unless there was internal problem (high resistance) across relay contacts.... Relays are not exotic, the are basically just a switch...

Dale

[Devastator]

Having the 2 fuel pumps and the ignition hooked to the same relay made starting the engine shakey. Sometimes it would start, and sometimes it wouldn't. Since switching it to separate relays, it starts every time. I also burnt out a relay with them using the same one. Might have been a coincidence, might not have been. I only know that I wasn't consistently getting spark with them wired to the same relay and was after separating them.

[volksbugly]

Interesting, What amperage was the relay rated at?

FuelPump Amperage:

Code: Select all

Walbro "255" LPH
Volts        PSI   AMP
12.5          58 	9 	
12.5          73 	10.5 	
14            43 	8 	
14 	        58 	10 	
14	         73 	11.5 	

Just the fuel pumps alone are already pulling 16 to 23 amps
This is just for a basic walbro 255, not sure what pumps you have but these are fairly efficient

[Devastator]

I'm running the Walbro 225 and a facet style low pressure pump.
I think that the relay is rated at 1 amp less than I was pulling.