3.0 carb problems

[Mrrieser2]

Sorry new to this whole boating scene an this site couldnt figure where to.add this (BUT I NEED HELP) i had the boat in water ran good idle an in reverse good with a little throttle but full throttle it went like 10 mph an backfire... CARB.HAS BEEN REBUILT AT THE MARINA LESS THAN YEAR the owner provided paper work... But like I said im.new boat owner an need help thanks in advance

 

[southkogs]

Mrrieser2 - I moved you into your own topic.

3.0 Mercruiser and you're able to idle, but when you throttle up to WOT it bogs out and backfires - correct?

I'd see if the paperwork on the carb job was warrantied. If so, might be worth a trip back to the tech.

 

[alldodge]

Agree probably carb, but since its new to you, suggest compression test and check timing.

What year is the boat?

 

[Mrrieser2]

Yea I'll call them I dont know if you can see this or zoom in but the previous owner took it in an the tech rebuilt the carb then also stated that all compression was at 150 but backfired still

 

[alldodge]

Backfiring is caused by incorrect timing and/or not enough fuel at higher rpms. Can be other things but just assuming right now that motor is sound

Since the tech said compression was 150 and it was still backfiring, then I would not pay any attention to what was said. I would think different if the reason for backfiring was also stated. He sounds like another mechanic/tech by name only

 

[Mrrieser2]

So that being said do you know the firing order/ how to time it or should I just visit another TECH

 

[alldodge]

Can provide that info but need to know the engine serial number, or at least the year.

 

[Mrrieser2]

1990 chaparral 1800 sl

 

[southkogs]

I did a quick lookup on the company on the invoice - they seem to have a good reputation. The work was done under a year ago. It might be worth giving them a call and telling 'em what's going on. Maybe something's under warranty, or just to get a new customer maybe they'll cut you a nice deal.

 

[alldodge]

I did a quick lookup on the company on the invoice - they seem to have a good reputation. The work was done under a year ago. It might be worth giving them a call and telling 'em what's going on. Maybe something's under warranty, or just to get a new customer maybe they'll cut you a nice deal.

You bring up a very good point SK, I didn't read the invoice just took the OP's comment. The invoice does say the carb was rebuilt, timing was set and all OK and the end after test run. I should have read the invoice

Motor can have one of three different ignition systems

Timing 1 BTDC if EST distributor, must be set using base timing mode
Timing 8 BTDC if Points or DDIS ignition
Firing order 1-3-4-2
MR43T plugs gaped at .035

If you have EST distributor let us know

 

[RaceCarRich]

When I had my carbed 3.0L, one day it would idle or could be feathered in reverse. Was the fuel filter at carb inlet. I guess with prop pitch it was more load on the fuel starved motor to go forward. I had to reverse back to the dock feathering from stalling the whole way.

 

[Scott Danforth]

Im thinking lean sneeze

if it sat for a while, there could be debris in the carb from fuel going bad and the check valves for the accelerator circuit are plugged

if you pull the spark arrestor (air cleaner looking thing), and with the motor off and the choke plate held open, have someone give the throttle a quick pump. you should see fuel squirt down the throttle bores. if you don't, your accelerator pump ciricuit is plugged and you are running lean

 

[Mrrieser2]

Ok I'll check into the last 3 response post first thing in the morning I work 2nds an at work thinking about this damn **** ... but thank you to everyone helping along the way.... I'll inform you guys in the AM THANK YIU ( 1ST TIME BOATER )