How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Jason Your Own Question
Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 14303
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
44667847
Type Your Boat Question Here...
Jason is online now
A new question is answered every 9 seconds

Just had starboard quadrajet rebuilt. While at idle rpms

Customer Question

Just had starboard quadrajet rebuilt. While at idle rpms will drop. I'll hit throttle and rpms will come back to normal after couple of minutes drop again
Submitted: 1 year ago.
Category: Boat
Expert:  Jason replied 1 year ago.
Hello my name is ***** ***** am I speaking with?
How old is the gasoline the engine is trying to burn, and have you tried running it off of another tank yet?
Have you checked ignition timing to make sure it is holding a steady 8 BTDC and not bouncing around?
Expert:  Jason replied 1 year ago.
Are you still with me?
Customer: replied 1 year ago.
Still here. Gas is fresh. Unknown about timing. Going back to boat now to check timing. Never had problem with idle till carb rebuild. Can't see why timing would have changed but will check
Expert:  Jason replied 1 year ago.
If you did not have an problem with idle until the carb was rebuilt, why was the carb rebuilt in the first place? And when did this happen?
Customer: replied 1 year ago.
at startup I was getting black smoke for about 10 minutes then it would clear up and runs fine
Customer: replied 1 year ago.
I was thinking floats problem or Welch plug problems but smoke is gone now
Expert:  Jason replied 1 year ago.
Black smoke is also a sign of low engine compression. Have you compression tested the engine?
Customer: replied 1 year ago.
it is a 1989 and never had any work done on the carb before it was time
Expert:  Jason replied 1 year ago.
What I would do is check compression first. It needs to be 100 psi or better on all cylinders. Anything below that and the engine either has mechanical damage, valve issues, or is worn out. If compression passes, I would replace the carb with an edelbrock or similar. Not all carbs can be rebuilt. The rule of thumb is by the time a carb is 10 years old it has a 50/50 chance of being rebuilt. As it gets older those odds go down.
Specially what happens with them is the way the carb is built is they use a very cheap pot metal to form the carb body. They use this metal because it is easy to drill through. The metal is porous. So what they do after the carb body is made is they put a sealing glaze finish on the carb body. Over time that glaze deteriorates, and the carb starts leaking internally.
Does that all make sense? If yes, did you have any further questions on this issue?
Customer: replied 1 year ago.
Compression is good mechanic said. It was only at start up(smoke). Could start the boat 8 hours later and had no smoke
Expert:  Jason replied 1 year ago.
Did you see my last reply?
Expert:  Jason replied 1 year ago.
I think that should do it. But I work for tips so I do want to make sure you are happy with my service before you go. If you had a further question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.
Questions do not close out, so if you have to come back later on with follow up questions to the issue you still can even after doing a rating.
Thank you
Jason
Customer: replied 1 year ago.
What do you think about a vacuum leak?
Expert:  Jason replied 1 year ago.

A vacuum leak would cause a constantly high idle that would never come down.

Customer: replied 1 year ago.
The guy who rebuilt the carb is coming back to the boat in the morning. The boat ran perfectly fine prior to him rebuilding it. Just had the smoke at start up. After smoke went away boat ran great. It is for sure the carb and I'm not sure what it is.
Expert:  Jason replied 1 year ago.

If all he did was the carb and it idled before he touched it then by simple deduction the problem has to be in the carb. That is assuming he didn't touch anything else. Does that make sense?

Customer: replied 1 year ago.
I was there when he took it off and was there when he put it back on. He did not do anything else but rebuild the carb. I'm ready to toss this guy in the water
Expert:  Jason replied 1 year ago.

Lol, I know how it goes.

Based on our conversation so far simple deduction tells me the problem is still in the carb.

Expert:  Jason replied 1 year ago.

Let me know how you make out. I'll keep my fingers crossed for you.

-Jason

Expert:  Jason replied 1 year ago.
Hello, I noticed no rating has been put through yet. I wanted to make sure that you didn't have any futher questions on this. Was there anything else?
Expert:  Jason replied 1 year ago.

Hello, just checking in. Any progress?

Related Boat Questions