True.....

Yes ,I had a 7.4 L carb for 6 years, spent only a few hours on it, have had 502 MPIs for 6 years and I must have spent more than 700 hours on troubleshooting and the like. Actually more troubleshooting than enginehours...

Dave N- you said to make sure the knock sensor or IC wires are not touching a plug wire. Is this only a problem with cheap or old plug wires. Could a good set of 8mm MSD wires create the same problem?? Do they actually have to touch or just be close? thanks-

Dave , you are my hero. . A plug wire was touching the ignition control wire. Put some tape on, extending the protective plastic cover and the problems appears to be gone! Thank you all for your help.
Tried to attach a picture of two identical plugs both run in the No1 cylider, the left using the "30 psi" regulator and the right using the 43 psi regulator. Which one should it be?

mats,
Glad to hear you found it, and glad to hear I was actually helpful for once

Looking at those plugs, the one on the left (30PSI) does look pretty white. I think the 43PSI one looks better. No soot or anything with the 43PSI regulator?

Dave

Mats, is there a performance difference between the different regulators now that you have it running good again? Was anything else done to the boat, performance wise?

By the way.....What model Baja do you have?

The boat is a Baja 235 Force. The only performance mod is a Rex(GIL) exhaust.

Yes, I also think that the 43 psi plug looks more normal. It has only been running for about an hour but there is no soot on it so far. The 30 psi plug has been running for more than 10 hours and I think it is whiter than it should be. Still, the difference is smaller than you would think. I read somewhere that the flow through the injectors are proportionate to the square root of the fuel pressure. That would mean that the 43 psi would flow 20% more which is quite a lot. The boatspeed at WOT is about the same. Well, I continue with the 43 psi regulator and see if the soot builds up.....

Thanks again guys.

mats glad to hear you found the problems


dave great call.......now you have to keep up the great work !!!!!!!!

On the scan tool, the TP sensor only reads 73% at WOT. Is this of any sigificance and can it be adjusted? the throttle plates open fully.