my drag is surging help

[Wild Bill]

I have a svs Drag that was working fine last time until i tried to plane and it wouldn't. I omed the stator and trigger and they looked fine but the purple trigger wires were suspect so i repaired them. I went out today and when i tried to plane off it surged like crazy. I have good fuel pressure while this is going on. I put a new stater on last year and it ran great until now. Any ideas?

[25two.stroke]

Sell it to me and your problems will go away!

Did you check the vacuum lines to the pressure reg and to the ecu? If you get some condensation pooling in the lowest spot in the ecu map sensor line it will cause inaccurate vacuum reading and run rich. Also fuel residue clogs those lines (and fittings on the svs) up.

[Michael J Giesler]

I have a svs Drag that was working fine last time until i tried to plane and it wouldn't. I omed the stator and trigger and they looked fine but the purple trigger wires were suspect so i repaired them. I went out today and when i tried to plane off it surged like crazy. I have good fuel pressure while this is going on. I put a new stater on last year and it ran great until now. Any ideas?

Do you have a video of it

[XstreamVking]

My 3.0 efi surged and lost power, ended up being chipped reeds. Diff engine, but just throwing it out there for thought.

[Dave S]

My surgin is Draggin....:p.....

[Wild Bill]

Update sent the ecu to Brucato they said it had problems, so I got a new one. Now it runs to 3200 then settles to 2800 rpm. Changed trigger it holeshotted once then same thing. Changed switchboxes stator rectifier took the yellow wires off the rectifier no luck. Reeds are good. A year ago I replaced all the hoses and filters on the fuel system. I also put an Autometer fuel pressure gauge to monitor pressure. The last time I tried it the gauge wiggled about 2 pounds, not sure it does this all the time as I am usually not watching the gauge on the hole shot.
Fuel air spark what am I missing.
The only person in the area that I trust and know can figure it out is really busy, told me you are a smart guy you can figure it out. I am pretty sure he overestimated me.

[Wild Bill]

And the injectors have ben cleaned by CIS and given a clean bill of health.

[David - WI]

Maybe pull the plugs and try to see if it's the 3 left or two upper or random cylinders acting up?. :confused:

[Wild Bill]

Going to get back after it this afternoon, Vern told me to back it in on the trailer and put a timing light on each cylinder to see if something is going on when I rev it. The ramp is so busy I gave up last time, maybe I'll try on Monday.

[Wild Bill]

Finley fixed it, got some ramp time with the timing light. found spark scatter on number two cylinder. Put new switchboxes on it, now it likes me again.

[Dave S]

Fightin swbox......... Yep

[Michael J Giesler]

What was wrong with your ecu I hope you got yout mercury 849 box back

[Wild Bill]

They said the injector drivers were getting erratic at 4000 and 8000 rpm. I am not sure I believe them. I am going to put it back on and see what happens soon. Yes, I got the box back. It is the A-13 box