Ignition or fuel problem

"help! 165 6cycl 1977 mercruis

"help! 165 6cycl 1977 mercruiser
Problem : stalls and dies on the least bit of acceleration but idles great !...ive put on a new fuel pump, changed the plugs , set the timing which holds nice even marks under the timing light , replaced vacuum advance mechanism, Ive cleaned and rebuilt the carb with a genuine mercruiser carb kit, set and reset both the float level and float drop, im really stumped on this ..some history on the boat--boat hadnt been ran in a couple years so i replaced both water pumps. i did find a major bare wire from the alternator that was against the block and my amp gauge is maxed out on the high side, no apparent issues with the gauges or lights other than high voltage on the amp meter. Engine will at times surge up and down hence the fuel pump replacement . i can sometimes very carefully and slowly forward the throttle and get it to go to higher rpm's but it real tricky to accomplish this and if i try to put it in gear it immediately dies . Ive adjusted and readjusted the carb settings and float settings to no avail ...same thing...idles fine and dies immediately when giving throttle...it does this whether or not the throttle control linkage is hooked up or whether i move linkage by hand...it would sure be nice if you guys could save me a trip to the looney bin !!!..thanks a lot ..one more thing ..i removed the fuel tank and cleaned it inside like new and replaced all fuel lines..also, all the manuals ive seen do not show my distributor for this engine,,,my distributor has a condensor but no points...thanks again"

"It sounds like the accelerato

"It sounds like the accelerator pump in the carb is not delivering a decent shot of fuel. Pump the throttle and eyeball down the carb throat (engine off). You should see a solid shot of gas gush out. Also, there are usually adjustments to increase the size of the shot (by moving the arm to a different location). You want to use the position that squirts the most.

Jeff"

"Hello Jeff and thanks for the

"Hello Jeff and thanks for the reply ...i tried that exact procedure this morning. I dont have different holes to position the pump rod in so i made several different adjustments by bending the rod. i tried shorter and longer adjustments. Thought i had it for a minute because one particular position allowed smooth idle and acceleration without stalling but only for a short time then it started back with dying out again. Another symptom is that sometimes it wants to surge up and down in speed even at idle but when i remove the vacuum advance hose from the carb and suck on the end it evens out and increases in speed ? ..dont know if this helps or not in the diagnosis. I did put a new vacuum advance on the distributor although the old one was probably ok since it worked the same as this new one ..One more thing ...i know its a no no but i was just curious so i bolted on a small 2 barrel auto carb just to see and it did the exact same thing..also rechecked timing and it was off from previous setting..reset it and it held steady .. This rochester carb was pretty rough looking inside so i soaked it in carb cleaner (not car carb -the original that i rebuilt) and sprayed all passages clear before rebuild. but, the inside is still kinda rough looking sort of like a sandpaper look to it . but as i said all the passages are clear . could the roughness mean that its just to worn ...the pump does give 2 squirts of gas but not strong ones in my opinion. and just trickles a little after a short weak squirt.......thanks a lot ...Paul"

When you rebuilt the carb did

When you rebuilt the carb did you blow out each of the jets and their passages? It sounds like one of them is blocked. I had one blocked so tightly that I had to use a 1300psi pressure washer to clean it out. Good luck.

"Paul: you said it sat a long

"Paul: you said it sat a long time; "bowl kinda rough looking sort of like a sandpaper look to it". The same condition exits throughout the carb whuch can't be seen. I'm with Jeff & Peter about the accel. pump and jets--pump should spit fuel like a snake spitting venom. You may have grit and varnish cemented in the jets.

Todays' carb cleaners in a can lack the cleaning power of the past. Get a can of SEA FOAM and soak just the bowl with it overnight, then run it thru a hot cycle in the dishwasher upside down right over the spray head if the boss will let you--NO DETERGENT--it will eat aluminum. Don't let it dry; blow all the passages dry immediately when it stops washing. You may have to spray some carb cleaner in the jets again and blow them clean. When done run another short cycle with deterg. to clean the dishwasher.

No dishwasher; a deep old sauce pan with boiling water in it will work--think of it as a hot dip tank."

With different carb and the sa

With different carb and the same trouble I'd start looking at the ignition system also. Improper dwell will cause the symptoms you speak of. Marine distributors have no vacuum advance that I have ever seen nor have seen an ignition system whith a condenser but no pionts. I would verify what type of ignition system you have and start troubleshooting it.

"First..thanks for the replys

"First..thanks for the replys i really appreciate it ...I will try the sea foam/dishwasher trick ...i really cant find this type of distributor anywhere in the Seloc manual that i have it has the big round cap type rotor under the cap and under the rotor is a condensor and what looks like an ignition module ..no points are there even though the spec label on the valve cover calls for a point/dwell setting ? ..and there is a diaphram plunger type vacuum advance with the rubber hose going to the carb ...conventional type coil mounted next to distributor...could this be a modified distributor by a previous owner to simplify the ignition maintinance ?( i read that that can be done in the seloc manual)...One more thing...the new rubber cup included in the rebuild kit seems small , it doesnt start to contact the sides of the (plunger bowl?) until it is about 2/3 of the way on the down stroke ? is this normal ? ..thanks guys"

Love those old 165s. You may

Love those old 165s. You may have an after market electronic ignition no points in them. I put one on my old 165 from triple A marine. it saves a lot of trouble and works great

Ben

"If you are getting a weak lit

"If you are getting a weak little spurt, that's your problem. Either the passages are not fully open, or the check valve in hte bottom of the pump well is blocked. I assume the pump isnew and functioning properly?


Jeff"