350 mag bogging stalling

"got a mercruiser 350 mag 1992

"got a mercruiser 350 mag 1992 (carb). this thing will idle fine, you can rev it in neutral, runs fine, you get out on the lake and through out different rpm's it bogs and sometimes stalls.. Its real intermittent, not really easy to troubleshoot.. I have changed out fuel filter, gas, plugs and even took the carb apart and cleaned it out really good.. It seems like something maybe plugged then comes unplugged or i may be loosing fuel pressure. it will bog out and stall, but start right back up and run completely fine.. when it does bog out i am definetly not on all 8 cylinders, then all of a sudden it is back on 8 and run fine.. i can creep around the lake just fine but when i give it gas it starts its crap again.. sometimes i get on plane sometimes it will bogg out before that, its all over the place and still feels like it could be a fuel issue. i did have a problem with some gas that i put in it, borrowed a tank from the neighbor and wound up having particles in it.. i drained the tank with a syphon and put new gas and filter in it and it ran fine for a few days then now its acting up again..when the boat moves around like bow going up or hitting waves it acts up.. maybe the pick up in the tank clogged?? maybe a fuel pump?? need some advise here..
thanks

Bobby"

"I guess i'd take the cove

"I guess i'd take the cover and breather off the carb then tool around the lake until it happened then spray some starter fluid in the carb - if this returned the system to normal it would definitely indicate a fuel problem (assuming the breather is clean - check this). That would also confirm it was not your carb. Then I would try to figure out if there is a small inlet filter to the carb beyond the spin on water-separater - some have it and some don't. It is a small filter that screws onto the inlet of the carburator. Then I would go back to the tank - find the clean out port in the floor and remove it, open up the clean out, pump the gas out with a drill-powered pump. You might need to take off the level sensor which might also be installed in the clean-out port. shine a flashlight in there and have a look. If there are a lot of particles, will need to flush it out with clean gas. This is a last-resort kind of thing, but it is actually not that hard - just need to be very careful with the gasoline for obvious reasons. If spraying starter fluid in the carb is not the problem it might be ignition and it might just be that one of the terminals on the distributor cap is getting oxidized, but it sounds like a fuel problem."

"there is no other filter in t

"there is no other filter in the line at all, just that water/fuel seperator..Even where the fuel line goes into the carb, there is no little screen like I have seen on other stuff. I am going to pull the pick up out of the tank and check that all out, make sure the screen isnt clogged. If no problems there I am heading towards the fuel pump.. sound good to you? Its really weird, seems like under a load only some of the time it does this crap, only when the boat moves around it does this.. It will sit at the dock or on the hose and you can rev it up and it sounds totaly normal.. I dont get it.. its hard to troubleshoot this intermittent stuff.."

"Hi Guys, We have a 23' Ba

"Hi Guys, We have a 23' Bayliner with a mercruiser 5.7L engine and we have been having problems with it suddenly losing power, and backfiring, and then there is a smell of gas. This is after about 20mins of running at around 32000rpms. Temp and oil gauge normal. If we wait a while we can start up again but cannot get up on plane or major revs as it will cut out again with more back firing. We have had it serviced and the mechanic has changed the fuel filter and he found a little piece of loose silicone near the check valve which he removed but the problem persists. Any suggestions? We are feeling very frustrated over this repeated intermittent problem.Thanks"

Hi Sarah: Please start a sepa

Hi Sarah: Please start a separate posting.

Larry:

Your ideas are good

Larry:

Your ideas are good but dangerous. Drill pump subjects fuel vapours to ignition sparks from the drill armature; a backfiring engine driven w/o its flame arrestor--boat fire/explosion; shining a flashlight around an open fuel source--needs to be an OHSA approved flashlight for that use. JMHO

"Guy I agree its very dicey.

"Guy I agree its very dicey. Just a few months ago I had some bad gas (water) and could not siphon it out because of the 90 degree fitting at the gas tank. The only way i could get all the gas out was to open up the access port and pump it out. I was very nervous the whole time, and your cautions are very well advised. Safety first."

"today i yanked the fuel pump

"today i yanked the fuel pump to pull it apart to inspect it, i did find that the vaccum port that runs to the carb was completely clogged, the rubber hose was clear but it was totaly clogged at the pump.. I threw the old pump back on because i cant get the new one until tomorrow and it takes about 5 minutes to take off and put back on..i did not get a chance to take it out because i had to bounce to work..It did start an idle perfect, but that hasnt been the problem, only when it has a load on it problems occur.. I did order another fuel pump because this one does have some signs of wear in it, probably an original from 92 so i will can change it now instead of next year.do you guys think that clogged vaccum line has anything to do with this??"

"do you guys think that cl

"do you guys think that clogged vaccum line has anything to do with this??"

No; that is a safety bleed off to the carb in the event of a diaphragm leak. Keeps it out of the engine bilge.

"So you leaning toward fuel p

"So you leaning toward fuel pump?? It did seem a little worn when i had it apart earlier. It idles fine, revs in nuetral fine but when i take it out under a load it seems to intermittently bogg down. it might be right away or it might be down the lake a little ways.. it seems like a fuel problem to me. this boat ran great up until a week ago when all this started after a bad tank of gas. I syphoned it, put new gas in it, changed the filter and took apart the carb and cleaned it, changed plugs too..It ran good for a few days then all the same stuff all over again.. I dont know."

"I have been reading a few oth

"I have been reading a few other posts and the coil has been the culprate in a couple of similar situations, I personly never seen a coil do that, they either work or they dont in my experiences.. what do you think about that?? the coil taking a dump under a load but normal in any other condition??"

Coil is possible but fuel is m

Coil is possible but fuel is more probable. Could rule it out with a can of starter fluid spray.