Jump to content

Major Timing/Backfire around 1,800 RPM - 2006 C4 Avalanche

Recommended Posts

Been having issues with boat for 18 months now (owned for 5 years) and have spent $10K at boat mechanics/dealers (new CPU, new top end, new cap/coils, various sensors) and still not working.  Always starts and no issues at idle.  When under load around 7 mph/1,800-2,000 rpm starts to misfire badly and will repeatedly do this - very heavy timing/misfiring when bumping up against this rev range.  Sometimes it will get through the issue after 15 -30 minutes of trolling and trying to get on plane - seems like it just catches and timing issue goes away - maybe crazy but it seems that if water is rougher or going over wake it allows it to catch more easily.  Once through the issue will  run absolutely perfectly until stopped.  Very rarely (but usually when been out on a bouy it will start and run just fine immediately but after 2 minutes then goes into limp mode and then the same issue happens.) Local dealer/mechanics are stumped - (Vancouver, Canada) - and I don't have a limitless budget.  Basically we have nice looking floating slow moving island/tanning bed but no surfing.

Really want to get this sorted out. Still love the boat and wave when it works so would love to figure out what the issue is.  Have the time this off-season to investigate issues. 

Wondering if this could be related to fuel pump/corroded wires? Other ideas or suggestions would be welcome? 

2006 Avalanche C4 Storm Series 

New core put in 2017

Approx. 300 hours on boat 

Share this post

Link to post
Share on other sites
jtryon    14

black scorpion 330?  are you getting good constant 14.2-14.3 voltage with the motor running?  have you checked the fuel pressure?

there are two fuel pumps from what i hear, one in the tank and one at the rear port side of the motor (black scorpion anyway) near the raw water pump.  i'm assuming you've done the easy stuff first like fuel filter, plugs and wires since you also did the cap and rotor?  if not i'd do all that as well as the IAC valve and maybe the CPS.

Edited by jtryon

Share this post

Link to post
Share on other sites
beau t    8

Have the injectors been cleaned or replaced, do all of the spark  plugs look the same as in is 1 black or a different shade than the rest. I didn't see anything listed about this above. with a car you can do a distribution test to check the injectors and should be able to do it with a marine engine to but i have not got to play with a computer that hooks up to marine engines to verify. this is just throwing out ideas since you have a long list above of stuff thats been done. Also can you free rev the motor and it not cut up?

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recent Status Updates

    • volzalum

      Sad this forum is not as busy as it used to be since so many jumped to the Facebook groups .. the FB groups are not nearly as easy to search, and the threads do not get organized well ...
      · 2 replies
    • MajaKazazic

      Are you  engineering students and searching for homework help services?helpmeinhomework.com provide all types of engineering assignment homework help services.helpmeinhomework has a reputation of providing premium quality online engineering assignment help for over a decade. Students all over the world find our services effective and reliable.Our Engineering Topic computer science,help with electrical engineering ,mechanical engineering,civil engineering...etc

      · 0 replies
    • MatthewsDave

      Sometimes it is normal for students to have trouble completing their finance assignments on time, seeking help from the team of experts in finance assignments to complete the assigned work on time. With the effective guidance of finance homework, we also strive tirelessly to improve your grade.
      Expert teams are available at any time to assist you in all types of topics related to your finance assignment, allowing you to easily complete finance homework on time to get an A + grade. You can certainly gather a lot of important information under the guidance of our energetic Finance faculty.

      · 0 replies
    • harlobra

      Heading to Lake Ouachita Arkansas in the morning for a week of houseboating and surfing.
      · 0 replies
    • Nick213

      Ordered a  sewlong cover...... hope it's as good as everyone says since there almost double the cost of others.
      · 3 replies
    • luluzer

      Winterization tomorrow for this homie. Seemed like the season flew by - let's hope winter does the same. 
      · 0 replies
  • Topics

  • Popular Contributors

    Nobody has received reputation this week.


Important Information

By using this site, you agree to our Terms of Use.