1987 OMC Cobra 4.3 V6 GM.

[dshakhba]

Hi Everyone!

Ive been having problems with my boat...the engine is not revving above 2200 rpm and after that when i give it WOT, it bogs down, backfires a lot of fuel from the carb and shoots fuel up. then the RPMs drop.

So, i figured the distributor might not be advancing. as my buddy gave it gas, i rotated the distributor and no, that wasn't the issue. I set the distributor back to its place. Then as I was driving, the rps suddenly went up...all the way to 3200 rpm and after a while even up to 3500!. this has not happened in a long time. i drove like that for 5 mins, slowed the boat down then back up to 3500 rpm. it seemed good. but then it dropped again but it was on and off.

The interesting thing was as your going 3500 rpm...the engine bogs down immediately a little and drops to 3200 for a couple seconds, then goes up, then drops again. It seems inconsistent. all this happens without me adjusting the throttle. After a while it went back to square one...same issue, not going above 2200 rpm. I WOT and it goes up to 2200, backfires through carb and the rpm drops and if i leave it on WOT, the engine will eventually die. Any suggestions? I'm thinking it is a bad fuel pump maybe?. This boat is my nightmare. Thanks guys.

 

[dshakhba]

I don't know if this helps or not, but as I rev the engine above 2000 rpm, I notice the carb jets dripping fuel into the carb. seems like the secondary fuel is dripping to compensate for fuel starve? This does not happen under 2000 rpm, but after that the engine backfires through carb like I said earlier, and the two round fuel jets in the center of the rotchester carb barrels drips fuel into the carb.

 

[Bondo]

Ayuh,.... Welcome Aboard,.... What carb,..?? Sounds like it really needs a rebuild,....

 

[dshakhba]

Hello,

I just rebuilt the carb recently. Maybe he did a bad job? The guy has a good reputation around my area....I don't know. Do you think it's a bad fuel pump?

 

[dshakhba]

Rotchester 2 barrel carb, the original one that came with the 87' 4.3v6 GM engines. 262 C.I. I believe its a 2G model? it has 2 fuel/air mixture screws in the front.

 

[Bondo]

.I don't know. Do you think it's a bad fuel pump?

Ayuh,.... Anything is possible, donno,.... Test it,....

'n carb rebuilds are notorious failures sometimes,....
It take a Thorough Cleanin', 'n blow out with compressed air,....

Most Diy'ers end up at a 50/ 50 chance of success,...